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• Peter Davi.d Go!ding Isotope Effects on_ Chemical Equilibria.

UNIVEHSITY''U/V/VFA\S/7T .MEMORIAL UNIVERSITY OF .NEWFOUNDLAND DEGREE EOR WHICH THESIS WAS PRESENTED • / GRADE POUR'LEQUEL CETTE THESE EUT PRÉSENTÉE. Ph.D.

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•-••••~-:,- v-.- W:V--^:- :-^-v :--v--; SOTOPi: lil;l'HCI'S ON GIRMlGM/RQUIIdKRlA

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1-"^ ' •;• MoMiorial/Univcrsitv of Newfound land"

ACKM VLEIXIENKNTS

The author wishes to_ egress his grateful- appreciation to Dr: J.M.W. Scott. 'The Initiation and maturation of this study would not be a reality were it not for Dr. Scott's patient supervision and encouragement. The author also - expresses his sincere thanks-to Dr. D.J. Barnes who, in innumerable discussions has translated vague concept? into sound empirical practice.

The stimulating rejoinder of Drs. E.. Bullock "and E-.K. Ralph, whether in serious discussion or recreation, has proven invalu­able during the course of this study. v

For the technical preparation'of the thesis, the author thanksyMrs. C. Piercey who patiently typed the manuscript and Mr. .P. King who devoted long hours to-drawing the diagrams.

Finally, the author gratefully acknowledges the graduate fellowships.awarded' him bv Memorial Universitv of Newfoundland and -the National Research Council of Canada.

! • ' ' PREFACE ' - J

The initial introduction to the thesis outlines the îjasic philosophy whiah prompted the present inycstigatiorn^JPri o r . .to

carrying out measurements which could prove definitive in the consideration of substituent effects on equilibrium isotope ratios, studies of the protium acids and their corresponding deuterium substituted analogues were conducted with a view to examining their suitability for measurement. This investigation

ti­

led,to a closer examination of the chemical and physical proper-tie's of phenylsulfinylacetic acid and some related compounds.

.-This additional investigation was not anticipated in the original scope of the work, and to accommodate the resulting lapse in continuity between the two areas of study, the thesis is conven­iently divided into-OPart I an$ Part II, each presenting separate Introduction, Experimental, Results and Discussion (Chapters.

P.D.G..

I

•y " '

ABSTRACT

PART•I

- The- thennqdynamic equilibrium constants, Kt(H)y 'of ""five monosubstitutcd'acetic acids, Rffi2G30H, where R= Cl, Ph, PhOJ, PhS, and PhS02, have been measured conductimetrically. The syntheses of'five isotopically substituted acetic acids, RCPy-CO0H, where R = CI, PhO, PhS, PhSO, and PhS02, are described and

~ J

.the . themodynamic equilibrium constants, K (D) , of three of i

these, R = CI, PhO, and PhS, arc reported. The calculation of secondary- isotope effects of the second kind for the three iso- v

topic acid pairs, RQl;>CCai/RQ)2roOH, where R = Cl,Pho', and PhS, has been accomplished by the appropriate comparison of thermo­dynamic' equilibrium constants, K (H)"/K .(D)i, and by'the comparison of isotopic slopes, mt(D)/n^(H). These slopes, mtfTy). and mt(H) , are-deri\red-from-"linear~leasTTTqû ^ the Classical and Shedlovsky conductance equations, and their• comparison is / demonstrated as a superior method in the calculation of isotope effects. ' - ï • • '•

" - ' • - - " • .• ' ' - :' ' \ i

A linear least squares interpolation to minimum deviation' of Shedlovsky K't values with variation of limiting equivalent èbrt--. dhctance- (A0) is tested as a suitable method_ fo-rfjthe calculation of ' n-eyyorted here disqualifies trie'simple inductive model-as a,légiti-mate description of secondarv isotope effects of-'the second kind..

^rne )f A0. -The ' effeciOof substituent variation on the" isotope effects

•Tl.ie correlation of diminishing isotope effect per deuterium atom With increasing acidity is also invalidated by the present re-suits. ~ • • . ••

_ PART II. : ~7 ' "©

Hie syntheses of 9-thia-9/lb-'diJiydrophenantIirene-9-oxide and thioxanthene-10-oxide are described. These-compounds have been partially deuterated at their respective methylene positions bv dissolution in alkaline deuterium oxide. Spectral evidence indi­cates stereoselectivity of the methylene protons in the exchange reactions-of both compounds. Unlike 'phenylsulfinylacetic acid, interchange of the methylene proton chemical shifts' does not > occur for either compound when the solvent medium is varied from dimethyl s^lfoxide-d6 to trifluoroacetic acid. The proposed conformational changé of thioxanthene-10-oxide from the pseudo-

- equatorml'- array in-chloroform-d.to the pseudoaxial array in trifluoroacetfc acid is considered.

\ 3

6

'CONTENTS

ACKMlUEEIXTlADiYl'S . . . . . \ , . . .. ' •. . . . • ^

PREFACE

ABSTRAIT . : • 4

1. INTRODUIT! ON

PART I

.1-1. On the Origin and Interpretation of

I sotojie. Effects . . •. . . 0 . .

1 - 2 ; 'Ilie Calculation of Equil ibrIum Constants •>

from Conductance .Measurements ". 3(

1-5. The Calculation of. /sotope EfLEER's

EXPERIMFNTAE • \\ - . > ' V

2-1'. \.Ceneral Instrumentation f' ' ' " • 'T - ' , • ^ ,

2-2:-- -Conductance' Inst*^^.tation . . ..•. . .

2-5*' •' • M a t e r i a l s . '. C . . .'~- '. .". .'.'-.'. . 1 ' C ."'T "6

. - l

' \ " • , •*

- ' ) ' - h . 7 . •

7

r " 1

rA.

RESULTS

• 1 Ce 1 1 Cons tant i

; ~ ' • Conduct anccdlesul t s . .-.

3-3-. Isotope E f f e c t s . . . . • . . . ' / . . . . . . . ] (i

5-4. L im i t i ng Equ iva lent Conductance (A,-,) Values . . . . 11

DISCUSSION

4 - 1 . Thermodynamic bqui 1 ibrium Constants 114

4-2. Isotope E f fec ts 1 2S

4-5. The E q u a l i t y 0 1 A c (IE) and A,-,(D) ; 132

. Summary ; . ]yo

PART II

INTRODUCTION

• " ' J ' - O n - t h e O r ig in o l the Magnetic Nonequjvalence

of. the Methvlene P rotons , in-

Phenylsy] 1 i n y l a ce ' n c Ac-id \ . . . . $ . .- \ 1-4.

•• ' _ • $ • • • - . 8

h - K I n s t r u m e n t a t i o n ' L S I -

d-:. -Materials ' ' 1K2

.RPSUETS AND DISCUSSION,

7-1. 9-Thfy-i\ 10-d ihydrophcnantl trcne-;) rôxicle .202

7-2. Tluoxant bene-10-oxide . . . . . . . . . . 208

^5 Suiiimarv .'——?.. . .' . ',21.7.

APPPNDIX 1 . . . •.' . . .• . . .. '. . '

APPENDIX II,. T . . . .

APPENDIX III - ,t ;• . . .. . • . ... . ' '. 2,5'

APPENDIX IV . . . . . . . . . 208 .

5-2. 'Ihe Proton-Dcuteron Exchange Reaction of

Phenylsulliny]acetic Acid-. . . . . . . . . . . . . ]d6

5-5. N.m.r. Spectra of Partially Exchanged -., — " 1 ' ' ^ • • . ; • ; y y 1

Phenyl su] f jnylacet ic Acid , .• 175

ENVERINIENTAK, , .

;

CHAPTER 1

INTRODUCTION

1-1. ON THE ORIGIN AND INTERPRETATION'OF. ISOTOPE EFFECTS

THE CORRELATION OF STRUCTURAL CHANGE WITH CORRESPONDING

RE ACT IV ITY , CHANGE HAS REMAINED A TOPIC OF INTEREST., IN;/THEJjLJeJld-.

OF CONTEMPORARY PHYSICAL-ORGANIC CHEMISTRY. STRUCTURAL VARIATIONS

EMBRACING a WIDE.REACTIVITY ORANGE HAVE BEEN STATISTICALLY TREATED

[ C . F . (1)3, AND THE PHILOSOPHY OF THEIR INTERPRETATION HAS BEEN

CAREFULLY CONSIDERED [ C . F . ( 2 ) 3 . BY. 'DEFINITION, , HOWEVER, THE

MOST SUBTLE VARIATION I N STRUCTURE MUST BE ISOTOPIC SUBSTITUTION,

WITH-THE CORRESPONDING REACTIVITY CHANGES DENOTED AS " ISOTOPE 7 / '

E F F E C T S " , • .. ', . .'

IN^THE INTERESTS,OF CLARITY 'AND CONTINUITY, THIS PRESENTATION

WILL BE restricted TO THE CONSIDERATION OF ONIVY ONE ISOTOPIC P A I R ,

NAMELY HVDROGEN (H ) AND DEUTERIUM ( D ) . I N THE CASE OF CHEMICAL

EQUIL IBR IA , AN ISOTOPE EFFECT IS DEFINED BY THE RATIO O F K(irj TO

K(IEJ , K ( H ) BEING THE EQUILIBRIUM CONSTANT .PERTAINING TO THE PROTON

SUBSTITUTED STRUCTURE AND K ( D ) THE EQUILIBRIUM CONSTANT APPROPRIATE

TO THE .DEUTERIUM'ANALOGUE. - WHEN'RATE MEASUREMENTS ARE OF INTEREST,

THE ISOTOPE EFFECT IS_ DESIGNATED''AS THE. RATIO OF THE CORRESPONDING;

RATE CONSTANTS K ( I I ) TO K ( D ) . WHEN THE ISOTOPE EFFECT I S .GREATER 0 .

THAN, UNITY , I . E . ' K(H)/K(D)">1 OR K ( H ) / K ( D ) > L , I T . I S SAID TO B E >

"NORMAL!.' EFFECT, AND .WHEN LESS THAN-UNITY ,* I i E. K (H )/K (D ) <1 OR

K ( H ) / K ( D ) ' < L , I T I S DESCRIBED AS AN " INVERSE" OR "REVERSE" ISOTOPE

EFFECT. . ' ' '

in

A further" classification of isotope effects depends upon a consideration of the effect,of the-chemical process on the bond linking the isotopic "atoms ho*, the molecular residues. If this

*par-tiajlar—bond—i uiptin?ed-*or—pa isotope effect results; but if the'bond remains intact in the reactants', transition states, and products, th^isbtope" effect is . "secondary". 'Equations' [1]* and ['2] serve to illustrate.a'.' primary and a secondary isotope effect respectively.

[13

J o

m

Eh' - a\z - COOH + II2Ô -K'"-> — Ph.- QI 2 - COO-^ + U 3 0 ( + ]

Ph - cn2 - ' C O O D ' + D 20' *'k^ - Ph - a-h - c m ( r ) + \ ) J + y

Ph - m, - coon + H 2 O K W > ph - a i 2 - coo(-~-) + n 3o (^

p)i - CD 2 - coon + n2o ' -MIIL^. P h _ C D 2 . coot-) + n 3 o M

Secondary isotope effects in which the bonds from the iso-topic substituents to the molecular residues undergo spatial reorientation have been described by Streitwei'scr (5) as second­ary isotope effects of the yfir/st kind". -Secondary isotope

*Since hydroxyl protium and deuterium atoms exchange very rapidly in aqueous media,,K(D) must be determined in D20. Consequently, K(H)A'fD) of equation [1] includes not only a primary isotope effect but also a "solvent isotope effect".

i l Y

effects of the "second kind" are those in which no spatial reor-Y ientation of the rronQ occurs in the equilibrium or fate process under consideration. Examples of secondary isotope effects of • the y thirst and second kind are respect ixei>^given-by-Equa t-i on s - [-3-1 • and [4], These examples fonn part of a series of "reactions in-' • vestigatcd by Streitweiser and co-workers '(4). '

Eh - c - n + r/"-1 JiLLLL^ P h }ç}U + m

[3] • h f

p

a * G

Ph - c - li + . B V ) JiffiL-,. P J l . ' c J ; P + BH

a-h CM 3

Ph - c - u + \,{^ Ph - V ' "

[4] .a-h

H

C - Il + B ; V L -l iL^U* Ph - CT + BH • _ e D _ • • l c D 3

ai

i - ) H

Mayer (5a) , Bigeleisen (5); Melapder (ft), and-.cithers (5c, 7) have put forward rigorous theories based on statistical mechanics and the Redlich-Teller product rale Lsee-(8J] which'-allow the accurate calculation of isotope effects in chemical reactions.

- Although^these theories may differ slightly in emphasis, the -^differences arc of little consequence in. the present discussion.

The calculation of isotope effects in rate processes requires a

'Tnowledge of the molecular vibrational frequencies of the isotop-. ically substituted species in both the ground and transition states, and in the case of equilibria, these frequencies must be available—for— both-the-reaetant-s—and-produet-s——Hence—thq-theo---; rctical approach proposed by Bigeleisen"and Melander is of limited value in its final form, for the situation seldom occurs in which all the vibrational frequencies or the related force constants •

t

can be empirically determined [c.f. Bigeleisen and-U'qlfsberg (5c)-] Â notable exception is the'investigation" of the formic acid system by Bell and Crooks (12). The pKa difference between HCOOII and DCOOII observed by these workers was çin good agreement with the theoretically computed value using only empirical vibrational fre*-quencies. However, the measurement and assignment of vibrational frequencies of more complex isotopically substituted molecules in a condensje T'phase, in which rates and equilibria are usually ex--

i,__is an exceedingly difficult task.__Thus.,__an_accurate_cal-amined

cula'tion of isotope effects for equilibria, and rates is generally impossible. )

*This is not possible for rate processes since the vibrational frequencies or related force constants of the transitjion -states are not observables^ However, several serious attempts Tiave been made to calculate.kinetic isotope effects by employing multicenter transition state models [c.f. Westhpimer (9), Bell (10), and More O'Ferrai1 and Kouba (11)].

I s

,1 f liv in a pair of 11 ând D' substituted analogues is large relative to kf for all frequencies, the complex theoretical ex­pressions can be- simplified to a dependence on zero-point,jeqie /g\f

_t erni tr-anrl ~t h e~r?oto pT~" fdec"t

rci K(II>. -h -, „,, '. .., , 1.5] — ~ - =î O X p . ( J . . Û U . - À A U J

Kfl)) 2kT " 1

where -"h" is Blanck's' constant f "k" is Boltzmann's constant^ "T" is tlie absolute temperature, and "EAv" represents the difference'-in the frequency sums -of thp respective pr^lucts and reactants. bquation 151 implies that'Isotope effects are quantum effects and that they depend largely on a .double difference between the vi­brational " frequency sums of ' the products and rcac.tants of the isotopic analogues. '

By applying further approximations Equation T5] may be "si'mpTi fi~<xl~tb give ' "•

r t -i K(I1) -h ry 1, .„ „ -If] — = exy.- (1 - -) (z.u ->o.> JV

K(D) 2kT ' 1 .

Y In. this equation only the sums of those frequencies primarily associated with -the motion of the-hydrogen atom at the position of interest in the non-deuterated product and reactant are rc-quired, and these sums are represented by ZVj_| and Zvfj, respec­tively. • These approximations were employed by Strcitwciser for

c

•hho calculation-of sotope effects in rate processes. However, since k(ll)7k(n) can-be T c l a t e d to K(H)/K(])y(l'3)* ,• then isotope effects arising from equilibrium considérations may be\ ad arl a ted

-us-ing Rqunt-ion-]y6-]ry lTTCTP3rTs'tant. "c" in tquat ion [ OJ has - a .theo---retica] value of v7T~**, but Strei/tw'ciser (14) lias .determined the value of "c". to be about 1.35 (rom-Ni. cons iderat i on of suitable spectroscopic data'. By cinploy-in fb'quation 16] to approximate an isotope effect, the sums of all the vibrational frequencies in both pairs of isotopically substituted reactants and products arc no longer necessary. In extreme 'cases the summations-may be re­duced 'to a consideration of two or three vibrations or even a single vibration* (However, for more detailed calculations,usbig' the complete theory, sec Wolfsherg and Stent (15) and Willi (1 6)]

It is generally accepted .that protium-deuterium secondary isotope effects are primarily dependent upon zero-point cîiergy ydjd fpye '~~

*k((I)/k(n) is actually related to* (K(H)/K(D) in which K(H) and K(D) are the quasi-equilibriunv constants between the respective

« reactants and their transition states..

. A*l'he- tbgj retical value of T^ÏT results from the appl ication of the "infinite mass-diatomic oscillator" approximation, in which the hvdrogen atom is assumed to 'be only-vibrating in coni'unction

' . *' 1 -

with the much larger mass of the molecular residue.

'Ihesc differences, are Ln tuni dependent upon force constant . 1

changes1 which' can be attributed to steric interactions (14, 17, y 1

T *

18, 19, 20, 21 , 22 , 23)-. and such electronic'effects as hypcrcon-•juration- (14y 1 V 24/ 25, 2 Of" 27 , '28/,'" hvlhddization ' (14/787 19, 20, 29 , 50)','and induction (29, 31).

Streitwcisef--(32) has ascribed sccondaiy isotope, efi'ccts of the first kind to hybridization changes, but describes' effect's of 'the second kind' as those which "behave like inductive effects". Thçse criteria'have been crh ticized-by Halevi (29) who states, "a classification scheme based on,the presence or absence of signifi cant structural changes in the region of isotopic substitution is likely to survive longer .than:, one. based'on theoretical concepts, • no matter how well established these seem to' be at the-tunc". This criticism may well be considered trivial since structural changes' are themselves usually based on theoretical concepts (e.g pcSs'tulaYe Indeed, in his review (29), Halevi attempts elaboration and interpretation of secondary isotope effects in'tenns -of qualitative-theoretical concepts related to changes which are electronic in nature. He states, "deuterium bonded to carbon,is effectively more electropositive, but less polarizablc,-than protium. The principal factor responsible (for this electronic difference) seems to"be the anharmonicity of the vibrations involving the motions of the hydrogen atoms, which leads to different average bond lengths "and angles 111

deliberated ;uid normal molecules", and hence, a different charge distribution. This hypothesis that secondary isotope effects of the sc<:on£( kind behave'like inductive effects is supported-bv. the crf-fërr^of-^cTi^ on the equilibria of the carboxvlic acids listed- in Table I". In the case of a few ammonium ion acids; (33', 34, 35, 36), which show-behaviour similar to'that of the carboxylic acids in Table I, the effect is more marked; but this ha's been rationalized on the basis of-opposing inductive and hyperconjugative effects in the carbox- . ylie acids (29) . . • ' . - • - ' £ '

If'secondary isotope,effects behave like inductive effects, • . ' y

the magnitude of such effects might be expected to vary with structure and'with osition of deutèration, and consequently be

amenable to a linear free energy treatment in much the same y ^ '

manner as Taft's (3(7) treatment of "large scale" inductive effects Indeed,-Streitweiscr—f32)- has-successfully-applied-the— Ta ft equation to estimate the magnitude of isotope effects in certain aromatic' ring compounds from the isotope effects 'bf an , aliphatic scries. ^

Using the premise that inductive-effects are additive,. Scott and Barnes (38) have modified the Taft equation (37) from.

) • [7] log10K = (1.721 + 0.025)a* - 4.76 to ' • [8] pK = -('0r550 + 0.059) 5c*. + ,5.200 ±0.014 \

TABLIi I

SOME PREDTCEED AND OBSERVED ESOTOPE EFFECTS [TAKJ'M I5ROM(38)P

ESOTOPIC PAIR J OBSERVED CREn:,RENCrf) . CALOJLATED

ai3cooi I/CD3COOII

(Ql3) 3CCOOII/(CD3) 3CCOOD HC0OI/DC00I!

ai3ai2Ccoi-i/CD3cii2cooii

a 13ai2ctpoi i/p13CD2coon

Phai2COOII/PhCD?.COOH (+') m

ai3NH3/CD3NII3

ill . (>)

1.035(32)_ i Ï.D4 (52)

1.08 (29) 1.01 (54) -1.08 (34)

; 1.12 (34)

1.13' (56)

1.03 1 .014 I .021 1.021

1.085

(CH3)2NH2/(CD30 2N1B 1.32 (36) TAc)

*Thc recent •measurements of the K(11)/K(P) values - reported in I .vS ) for R-PliGi:aX.)H/R-PhCD:C(X)H, where R = I I , 4 -MeO, 4-N()2, are given in Table III, p

18

where a* is the Taft induct-i vc parameter for a substituent "X" attached to the, carbokyl group of bi carboxy 1 ic aci d . hhen "X" can beacons iderdd 'as a' substituted, metliyl group (-CX.. X2X3'J , then T.o* 'i s defined a . . ' - . • •

9.1 •.r.»*• = c i * (x,) + «,* cx 2) ' + o * (Xi)

Thi s modification is" simiiar' to Hall's (39) relationships, which a rc g i ven b\r : ' ••

I 10] pK. = 13.23 - 3.14 5a*

for primary- amines and

111] pK = 12. J.3 - 5:23' 5o* . • • ' ' .

for secondary amines. In these equations the 7,o* parameter refer to the sum of, the Taft constants fqr the groups attached to the _nitr.ogeir.atom—.'nie-Zo—values-were:'Calciilated-by-Scott_ancldbaiaic (58) for twentv-three carboxvlic acids listed in Table II, and used in the correlation of L'a* and pK shown in Figure I. 'Hie correlation of c* and 5a* (see- Figure II) gives a straight line which does not pass through the origin andtthe slope of which is not unity. However, this plot indicates that the premise upon which the modification of the Taft equation is dependent, namelv that inductive effects are additive,- is7ry and large a good one. ' Although the correlation ol" 5n* and pK based on the modification

a ;

TABLe II ' .

ACID STRHsfC7nI DATA RELATED TO TME TAFT CORRELATION A

FOR SDTSTimfiïACETIC ACIDS [TAKEN FROM-(58)] Y

ACID ( X - C O O H ) .. 0* X? " X3

' ' C E 3COOH ' r ' 0. 23

.0 ' •

F • F ' F 50

CCI 3.COOH () 65 ? 65' •ci Cl Cl 8- 70

CTn^CfjOH 0 '66 Br "- Br Br' 8 40

• I FPC O O I ] 1 2 4 ' " 2 05 F F " H 6 69

ŒC12COOH 1' 29 1 <•

94 Cl Cl H - 6 29 ( + ) • • - 00

(a-i3)jNai2.cooH 1 83 1" 90 ( C H 3 ) 3 N H H -

CNO12 COG 1 3 43 1 30 CN if' • H ' 4 62

ITEFCOOH 7 59 1 10 F H H 4 08

ai2'CGoa-n- ? 83.._ _.l ..05. C O O H -H - H. — Œ2CIC001-] s 2 87 1 ,00 Cl - II 11 3 88

ai 2Brcoon 1 90 0 92 BT II H 5 78

CE3a-l2COOI! 3 07 0 85 CF3 M H

cfiHsoa-i_axT(-i 3 12 ' 0 85 PhO H I! •

-

a-hiœai 3. 18 0 52 I H ' H 3. 58

. ai3oai2.caxi 5 53 •0 60 G-hO H H . • --

HCOOH 5 77 0 49 - - -1

N0 2ŒI 2 C H 2 C00H ' . • 5 81 0 50 •No 2ai 2 H Il , 1 48

.. .'/Cont'd

X = GXiXzXà ' AGIDvCX-CCXDH) - - pK---a*- Xy •- \: '--y^.. Ln*=F-

ci

CCcHs) 2QICOOEI . 'Y 3.94- fl.45 -JleHs C 6H 5 H 2.45

CCGHs)3CCOOH •• 3.96 - -- C 6H 5' C'GH5 ' C 6 H 5 ' 2.94

aizClOlaCOOH y ' 4.08 0.385 Q12C1 H H 2.52

CgHsQIzCOOII 4.31 0.215 C 6H 5 , H. _ Il ' 1.58

CF3dl2ai2COOH 4.49-* 0.320 CFsC^' II El' 1.50 '

C5H5a-I2ai2CCX)II 4.66 • 0.080 CgII5CH2 H IF "1.195

.a-I3COOII 4.76 0.00 H II H. 1.47 .

(•13 ) oCHCOOM '4.86,-0.19 QI3 Qi3 H "0.49

Œi3a-i2d6oi-i 4.88 -o.io a i 3 , H , H o.os

a i 3 Q i 2 a i 2 c œ n 4.82 -0.115 ai 3Qi 2 H ' H 0.88

•ai3ai2'(ai3")aicooH 4-78—^0721-—Œaa-ir^a-is 11—•—OT39~

(QI3)3CCOOH 5.05 -0.30 QI3 CH3 CH 3 0.00 t • ' - Y

Ail pK^ values were taken from (41): except those of the

monohalogenoacetic acids, which were taken from (542).

The 5n* values are- taken- from the correlation given by Equation

[8] (sec Figure I) and are' not derived from Equation [9].

FIGURE I A CORRELATION BETWEEN Zo* AND pKa FOR A SERIES OF SUBSTITITTED ACETIC ACIDS "[TAKEN FROM (44)1

FIGJRE II "A œ R R E L A T I O N BEfflEEN Zo* AND o» FOR A STORIES

i . " , OF-SUBSTITUTED ACETIC ACIDS [TAKEN FROM (44)]

o

(see Figure I) is inferior to that originally given by Taft, a more extensive, range of structures.^ embraced by Equation [8] '

• than was. usôd"'to establish t7 u a"^ n > [>7']- Deviations,from the

: strict, additiya_ty_of"2

stcric effects, but/ fjibse should be negligible in the case of , YJ •! * • - •

H, D, CH3 and CI)3 subsgtitucnts [Howeverb'see- Eartell 's investi-gar ion of nonbprided interactions (18, 19, 20)]. , '

Tlie value of a.* d;D) .was obtained from, equilibrium constant 'measurements made bv*Bates et al. (40) on the 'fjT3CXTX9H/CDX0011 -system, and similarly the value of-a*' fCB3) was obtained from an investigation of the (aia) 3COOH/(CD3) 3C00H svstem bv Streitweiser

. • . .. ' s

^ and Klein (52).- Substitution of the p_Ka's of CT)3C0ŒE and ' (ci)3)3COOH into Equation [8] allowed Scott and Barnes (3$) to 0

calculate values of 0.482. and -fi. OIL for. a* (Dj and G* (CD3) , respectively. These valut^cn/a* (D) and o* (CD3) were then used in. conjunction 'with the vali s_yof_p- _ fi).',_ai (Ql3)_and-aî—(Ph)----(see Table II) .to calculate the Zo* values of the following iso-tqric acid systems: M0OŒ/DCOOH, a^I2COTH/CD3CH2CC)OH,

(+) (+) • ai3ai2aX)ii/ai3CD,C(X9H, PhOl2CXWPhCD2CC0rl, aT,NH3/CD3NH3, and

Q ' . ( + ) (+) J "

fOI,')?NH2/(a)3]2NH2. From the calculated E G * values-Scott and . Barnes (.38) have recently predicted the isotope effects oï\he latter systems, and t^r^e' are compared (see Table I) with exper- ' mentally observed values determined by Halevi (34) "and Robertson '(.36, 43)'. -Adthough the predictions of the isotope effects for thc ^ acid systems are qualitatively verified, the observed'iso­tope effects generally exceeded the predicted effects bv several

r To provide more data with which to test the 1 lalevi-Streit-

weiscr-Taft inductive treatment of isotope effects, Scott and

Barnes (58,^44)' carried out conductance ; measurements , ,to .determine.,

the K(II)/K(I)) ratios for the isotopic weal acid pairs

4 - NO 2 -IN.l U - Q1 ? - 00011/ 4 - NO 2 - C d U - CI ) 2 - COCU I . and ' 4 - MeO- G 6! h - Π2 - 00t*l 1/ . ~'->

4-McaaY\dB,-CD;.-CaiIl. They also redetennincd the isotope effect

of the laïaizÇœil/laiCnpGCDH pair.. These acid systems were ohoscn

to test the adequacy of the inductive treatment, since the induc­

tive model requires to a first approximation that isotope effects

lTe jjiile]5endeht of the -nature of any group substituted in the 4-

-positi.on of the ring in the aromatic .side-chain.

Although the isotope el fecK^ratios determined by Scott and

Barnes (58,. 44) are in qualitative agreement with the Halevi-

-Streitweiscyr-Taft induct i\^ model, a .comparison of 1/n log10K(li)/.

K(D) and pK (II) has been deemed greater in significance and interest.* The ' inclusion of. the data Tor the acetic acid system

(40) with the results of the latter three arylace-tic ac/fd p~a±TS-..

suggests a trend 'in which the isotope effect per deuterium atom

declines as the strength of the acid increases (^fie Figure 11,1).

. — _ _ _ _ _ " - / y - * : . , -

"\'.d. Shiner (17)/ originally proposed the formula 1/n logi.KTIl)/

K(n) in which n = 3 for ai3CœiI/CD3CCXjH and n = '2T for the aryl-

ac e t i cwac i d s..

'0

2 5

FIGURE III

A P L O T O F + L O G I 0 K ( H j / K ( D ) v s . p IC , ' (H ) [ T A K E N FROM (44).

0 . 0 0 5

0 . 0 0 4

0 . 0 0 3

- 1 . 9 9 8

C H 3 C O O H

3.80 4.00 4.20 4.40 4.60

p K a (H)

4.80 5.00

Two observations emerge from the correlation of pK (II) with • • J • ' •1/n log 1 0K(II)/K(D) :

(1) The.predicted value of•1.02- for•the isotope effect .of the ldiCiH2Gœil/PhCD2cœiI acid pair'based on a*(D), is now much closer to ,the observed value of 1.01, i.e.- the inductive treatment is partially verified. -

(2) The isotope effect appears to be- variable and depends . on the structure of the acid- (38,44). This is not consistent with the simple inductive model, which, requires that the induc­tive effect per deuterium atom be independent of the molecular environment of the isotopic substituent.

The aim of the present work was to furnish further data which would test the correlation of diminishing isotope effect per deuterium atom with increasing acidyty (see ;.Figure III). The relatively strong isotopic acid pairs CIO 12COOI1/C1ÇD2COOH, Ph£ CTI2C00H/Ph0CD2COOll, PhSCI I2Ç80II/PhSCADyCOOI !, PhSOCI I.2Œ)ÔlI/PhSOCD2. CCOII, and PhS02CH2C00H/PRS02CD2COOI\ were chosen for investigation

P because previous studies have shown the protium acids to be suit-' able for conductance measurements (42 , 45., 46) and these pairs-would furnish points in the low pK (H) portion of the correlation (see Figure III). A linear least squares treatment of the data for the carboxylic acids examined by Scott and Barnes (58,-44) was employed to determine a tentative relationship between 1/n logi Q K ( H ) / K ( D) and pK (11). The resulting equation is

[ 1 2 ] 1/n log, 0K(Fp/KO)) = (6.56 x 1(T-3) pK. (II) - (2.66 x 1CT:. cl

This relationship ,v:as employed to predict the isotope effects, "flcip paiV's-uiider-consideration in '

the present investigation.'(see Tab le /III, and Figure IV).

PRQTIUM ACID

•ÇHjCOOH

4-Mc^C6IDCH2CCOH

CeHsOIzCOOH 4-NO2C.H .Œ2COQH

CeHsSCHzCOOH CeHsOŒzCCOi CIQECCOU CeHsSOŒzCOOH •' . C6H5SO2CH2COOH '

TABLE III THE PPvEDICATTTD ISOTOPE EFFECTS QF SOME CABDOmiC ACIDS

I 1 CALCULATED _ FROM A LINEAR 1EAST SQUARES TREATTEYT OF-OBSERVED pKq(H) AND ISOTOPE EFFECT VALUES

i ' - J

• - pAAÏTI) • - K(H)/K(D) CALCULATED j

[TAKEN-FKOM-.(41)] EQUATION [12]

4 1 .76 1 052 -

4 l -56 I

1 009 • - 4 1 .31 1 007

.3, .83 1 ^

0 994 5 43 j 0 9S1 3 i .14

1 0 972 •

- " 7 I 85 •\.

964 .

66 -• \

• " . 0 959 ' ' ' 0

1

•44 ' : 0. 952

[TAKEN FROM (44)] l . p S

i. 005' "1. DO'S 0. 996

X

0-006

0 004

0 0 0 2

0 0 0 0 Û ^ -1-998

£ -I 996 ^ .

0 2 - . - 9 9 4 O «J - 1 992

- l e * -1-990

-I -988

- 1-98 6

EXPERIMENTAL VALUE PREDICTEO VALUE

Vf

CH.-COOH

4-Me0-C6H4-CH2-ÇO0H C6H6-CHj,-C00H

-N0 2-C 6H 4-CH 2-C00H

. eH 5-S-CH 8-COOH

y Gc„h_-o-•6-5 r . C H 8 - C 0 0 H

•CHp-COOH 2 t f • !

C 6H r-S0-.CH 2-C00H / I

2-00 2-50 3 0 0 3-50 4 0 0 4-50 500

p K a ( H )

50

• i - : . 'nip, CALCIJIAITION OF n g u i U M R i i f f . ] CONST/VN'TS FROM CONIXO'AKŒ

i - - 2 a y V\J\ i N T R v O D U c n e ^ i y r o in i r CONDUCTANCE: MFTIIOD

A s s e v e r a l e x c e l T e n t a c c o u n t s ' o f c o n d u c t a n c e m e a s u r e m e n t s o n

• e l e c t r o l y t i c . s o l u t i o n s a r e a v a i l a b l e ' ( 4 7 * 4 8 , 4 9 , 5 0 , 5 1 , 5 5 ) ,

t h i s i n t r o d u c t i o n . a t t e m p t s ' o n l y a b r i e f h i s t o r y o f t h e c a l c u l a t i o n

o f e q u i l i b r i u m c o n s t a n t s f r o m c o n c e n t r a t i o n - e q u i v a l e n t c o n d u c t a n c e ,

d a t a . ' • ' . • ' • • ' • '

F a r l y c o n d u c t a n c e t h e o r y a t t e m p t e d a d i s t i n c t i o n b e t w e e n

e l e c t r o l y t e s , c l a s s i i y i n g t h e n a s c i t h e r w e a k o r s t r o n g . B o t h

c l a s s i f i c a t i o n s e v o l v e d f r o m a c o n s i d e r a t i o n o f t h e r e l a t i v e c o n ­

d u c t a n c e s o f t h e n ' s o l u t i o n s . a t c o m p a r a b l e c o n c e n t r a t i o n s , t h e '

s t r o n g e l e c t r o l y t e s l y a v î n g l a r g e r c o n d u c t a n c e s t h a n ' t h e w e a k ,

-lvl e c - t - r o l y t e s - w h i c h - d b e y e d - t h e - O s t w a J d - D i - l u t - i o n > L a w H ; 5 . v ) ~ ; •

1 / ' 1 A - c ' 1 5

K • c

w e r e c l a s s i f i e d a s w e a k e l e c t r o l y t e s . * S t r o n g e l e c t r o l y t e s

a p p e a r e d t o f o l l o w t h e S q u a r e . R o o t h a w , e m p i r i c a l l y f o r m u l a t e d b y .

* T h e p a r a m e t e r s o f e q u i v a l e n t c o n d u c t a n c e ( A ) , l i m i t i n g e q u i v a -

l e n t c o n d u c t a n c e (.A,-,) , c o n c e n t r a t i o n ( c ) , a n d e q u i l i b r i u m c o n -

s t a n t ( K J i n / h q u a t i o n s [ 1 5 ] a n d [ 1 4 ] a r e d e f i n e d m o r e f o r m a l l y

y . ' -f • -b e l o w . ' ' . ' ' •

Kolilrausch (54). This relationship is expressed by

[14] A = A 0 - R(c)?i'

~i n : "ch" ..'B' ': 1 s '- t) i e - fim ting- slope.. This- distinction, however, was not sharply defined and in several instances the classifica­tions tended to overlap.

Modern electrolyte theory classifies electrolytes tHf either ionogens or ionophores. Tlie former are typified by covalent molecides which rapidly produce thermoclynamically sfable* ions by a dissociation process in aqueous media, and the latter are elec­trolytes which exist as ionic lattices in the pure form. ' _

The specific conductance of 'a solution depends upon the number of ions per cubic centimeter of solution (n for the it-h hind of ion), their charges ( z ± c ) and their mobilities (Ti|), i.e. their velocities per unit of field strength ( 5 5 ) . Hence, the

—spec-i-fie-conductance—L— is-described~by"' " ' "

[15] L = En^c^lu, j -

-Certain organic reactions which produce thermodynamically un­stable carbonium ions have also been described as "ionogenic

A

reactions". The distinction between these and the above is obvious. . '

3 2-

In practice the specific conductance is an empirical observable' related to the resistance (R) of the solution by /

[16] L •=, K/R

where K IS the ceil constant, the determination of which is des­cribed below (see 3-1. CELL CONSTANTS;, pp. 85 - 8 5).

The equivalent conductance^(A) of the solution is readily obtained'from the specific conductance by employing the relation­ship, . '

[17] - A =

in which the concentration (c) is expressed in moles per 1000 g of water.* For a single neutral solute having a degree of ioniza­tion a, the ionic concentration is ac and the tribal-charge per molal ufiit is acF, where - F is a charge of one Faraday. In conjunction with Equations [15] and [17] this leads to

[18] A ,= aF(u+ + u_)

-Concentration is sometimes expressed as equivalents per unit volume of solvent, but in the present case of 1:1 weak carboxylic acids dissolved in water, molal concentrations were used in the calculation of equilibrium constants. ** '

where u + and u_ are, the appropriate ionic mobilities of the

species present at any finite concentration.

Hence, the variation of the equivalent conductances of1iono-

stant is primarily a function of the variation.of ionic mobilities

dominant effect of the degree of ionization.

Kohlrausch's Law (56) Implies that ionic mobility at infin­

ite dilution is'limited.solely by localized interaction with sol- V

vent 'molecules, as no other ions are within a finite distance.

Thus, the limiting equivalent conductance at infinite dilution

l..AùJ is the sum of the contributions of each ionic species, inde­

pendent of the nature of the others-species present, such that

phores completely dissociated in.solvents of high dielectric con

with concentration. Although'the mobility factor remains impor­

tant for solutions of ionogens-, it is superimposed upon the more

LW. Ao—^_K(u°+.J.+_u°=.|

and this can be also expresse d bv

[20] A 0 = X° + • + -5°

1 From-Equations [IS] 'and [19]

[21] A a(u+ + u.)-A, •o (u°+ + uO_)

mav be obtained.

From theoretical considerations based on an "ion atmosphere" model, Debye and Huckel (57, 58) proposed an expression 'for the electrostatic potential at a finite distance from an ion. This •expression allows the calculation "of; the "-"electrostatic ' free ener­gy* of an ion relativç^to a neutral particle of the same mass and size in a medium of known dielectric constant (D) and temperature (h-K This model provides an exprqssion relating the mean activ­ity coefficient .(f+) to the ionic strength of solution (I) , the ionic charges [ z x z ? _ ) and a constant (A) described as the Debye--Huckel limiting slope which is proportional to (DT) A 3. The expression for the -mean molal jonic activity coefficient (f ) is given by . . . ( • _ .

[22] -log f+ = AI"21 zjZz ] '

in which I is defined by the equation • . w"

[25] i h >:zi2.ci

i

where z. is the charge on the i '1 don at concentration c. l • . l Fquation [22] applies to extremely dilute solutions only but it has been empirically modified to accommodate higher concentra­tions by altering the denominator and adding a term containing

n *Both the Born charging (61) and ion atmosphere terms are given by this treatment, but these are easily separated. The latter tern only is considered in the present discussion.

55

[see (59) and (60)]. ' • .

From a consideration of Equations^/l3] y [21] and [22] an ex­

pression for the thermodynamic.equilibrium constant of a weak

monocarboxylic acid is given by

ct'"-c-f.2

[24]. K t

0.- a)fu

in-which f is the activity coefficient of the undissociated acid

at concentration c. Equations [15], [22] and [24] can be combined

to yield , ..

[25] log K t ' = log K - 2Ac^ •

for-a 1:1 electrolyte if f ->- 1. Hence a relationship between the

"classical" equilibrium constant (K ) described in Equation,[15]

and the "theirnodyTiamic" équilibra inn constant (K •) in Equation [24]

is obtained. , ,

Using the Debye-Huckel model, Onsager (62, 65) hasdrational-

izcd the Square Root Law and successfully predicted the magnitude

of the limiting slope (B) in Equation [14]. His treatment postu­

lates two factors which influence interionic motion in electroly­

tic solutions subjected to an electric field. - The first factor

is derived from the opposing motion of an ion and its oppositely

charged ion atmosphere, and is known as the electrophoretic

effect. The second factor, the relaxation effect, results from

the perturbation of the ion. atmosphere by an external field. The

ion atmosphere is continually "decaying" and "reforming",as the

\/ion moves through the solution. Although the mathematical treat­

ment of these effects is outside the scope of this thesis, the

— resulting equation - which accommodates '"'these "effects"', is relevant

and is given by"

[26] A = A 0 - (R + YAo)(acJ^

in which p. is the electrophoretic constant and y is the relaxation

constant. The* numerical values of S and y used in t)y present

thesis are based on values of the dielectric constant and viscos-

ity of water'(64) recommended by Fuoss and Accascina (65). hqua-i.

tion [26] is a limiting formula in which linearity with, (ac)'2 is

anticipated up to concentrations of_ca. 0.001 N, beyond'which

curvature appears in the plots corresponding to a progressive de­

crease in the slope with increasing concentration.

- ' Mo"re~cThb"ôiATT equations for conductance have

been proposed by Pitts (66) and Fuoss and Onsager (671. The Pitts

equation has. been satisfactorily applied to the conductance, of

hydrochloric acid. The equation proposed by Fuoss- and Onsager

treats the ions as spheres rather than point charges and takes

the form of . •- -

[27] A = Ac - S(c)h + Efc log c) + J(c)

in which S is the Onsager coefficient (y; + ,AQ) of the 1 uniting

• • • - • - i - »

law {see equation [26]}, F/ isa constant defined.in the* saine

variables as S, and J is a function defined hy^fon .size.

The Pitts and the Puoss-Onsagcr equations will not be dis­

cussed further as both' are outside the scope of the present w^rk.

Indeed, the. validity of their application to acid solutions has

been questioned in as much as'these treatments .consider ionic

•migration as "submarine-like" motiorç,whereas "proton jumps"

might be anticipated for the migration of hvdronium ions.

\

l-2b.. ' INDIRbri^.TllOnS: THF, SIMULTANEOUS GENERATION. OF Kr and Ar

V r

The Classical Plot. - Equation [24] provides 1 an''express ion . for the calculation of thermodynamic equilibrium constants arid

' • ' V1.. is stated as-

a'--c-f-i" [24] Kt; CI - a)fu

The classical approximations proposed by. Arrhenius (68) assumed no mobility differential with varying,concentration- and neglected

interionic'forces. If constant mobility is assinned then i

[28] a .= ' — '

and if interionic forces are negligible, Equation [24] then becomes

-L29T. — — — - K - - a 2 < Z

C (1 - a)

which is the classical'expression proposed by the Arrhenius Dis­sociation Hypothesis. The Ostwald Dilution Law is obtained by combining Equations [28] and [29]. With rearrangement these yield the expression stated' previously as Equation [13], namely

[13] ' ' , ' J - = J * + —Î2iL_ . ' -A. A 0 KG-Arj-

A plot of 1/A against A-c generates solutior fcu- A-

thé 1/A intercept and K from,the slope value of 1/K -A02.

\

trom

The Fuoss and Kraus Method. - Fuoss and Kraus (69) have proposed a treatment of conductance data which accommodates ' ..

~TSôTdTnTo .an abbreviated form of the Fuoss-Onsager Equation (see Equation [27]} for 1:1 ionogen solutions, the proposed relationship can be described bv

[30] " a = à r

M l -• S(ac)"/A0]

which is 'a cubic equation in a , the degree of ionization assoc-' • dated watjfr the ion concentration etc. A'corrected value of a can " then be. obtained from Equation [30] by successive substitution of a into the correction factor represented by the bracketed term in the. denominator of the right hand side of Equation [30]. This

4 iterative proccisjry'ra converges to yield a corrected value of

V iy-The correction factor 1 "- S(ac) VA 0 in the denominator of

the right hand side of Equation [30] may be expressed as

[31] . F(z) = 1 - z U - z[l-- z ( c t c O " W ^

y ' 3 /

where-z is yS(A-c) '/A0 . Alternatively, the continued fraction-can lip described in terms of the following cosine relationship

[32] F(z) = ' 7 3 cos 2[V3 cos-1(-53/.2,z/2)] ' I

'"• . • ••10' (

T h e d e g r e e o f i o n i z a t i o n , a , t h e n c a n b e e x p r e s s e d i n t h e a b b r e v -

i a t e d , t é n u o f '

a,,eu)

C o m b i n i n g l i q u a t i o n s -[2A] a n d 133 J , a n u ^ r e a r r a n g i n g t h e s e t o a

f o r m a n a l o g o u s t o E q u a t i o n [ 1 3 ] y i e l d s • ,

i f 1 i s a s s u m e d t o b e u n t t v u

A l i n e a r l e a s t s q u a r e s t r e a t m e n t o f t h e l ' ù V A a n d / i . o f p /

i ( z ) v a r i a b l e s , w h i c h h a v e b e e n c a l c u l a t e d f r o m a n a p p r o x i m a t e

v a l u e e l . / ' , , l e a d s t o a n e i \ v a l u e o f / \ 0 ; t h e l e a s t squares i n t e r ­

c e p t . T h i s g e n e r a t e d - v a l u e o f A, , i s u s e d t o r e p l a c e t h e a p p r o x i ­

m a t e , \ 0 u s e d i n i t i a l l y a n d t h e c o r r e l a t i o n - is r c p e ^ e A T . T h e •

i t e r a t i v e p r o c e s s i s c o i n m u e d . u n f i ] t w o s u c c e s s i v e v a l u e s o f - A ( ,

a r e t h e s a m e w i t h i n p r e d e t e r m i n e d p r e c i s i o n l i m i t s . T h e f i n a l '

v a l u e o f A n i s u s e d t o c a l c u l a t e f r o m 1 / K • A . -y , t h e f i n a l

l e a s t s q u a r e ' s s l o p e .

T h e S h e d l o v s k v I M e t h o d . - B v r e p l a c i n g »-, w i t h iV'l-, i n t h e

• ' " . - ' ; %, \ a b b r e v i a t e d E u o s s - O n s a g e r E q u a t i o n { s e e E q u a t i o n [ o O ] } a n d r e a r ­

r a n g i n g i h e t e n u s S h e d j o v s k y ( 7 0 , * 1 0 9J p r o p o s e d t h e f o l l o w i n g

q u a d r a t i ^ e x p r e s s i o n in'.a • , " ,

4 1

I T Î c h . c a n IJC s o l v e d - i n - f e r m s o f t h e - c v a r i a b l o r ' s e c Hqu'.'it i o n 131 ] h i s y i e l d s . ' •

f ... • ' ' ' . •

.h ) — [ c / 2 + ( 1 + z2/.V) S i c )

1 " i s S i c . ) l u n e ! " i o n j . s . s o m e t h u e s e x p r e s s e d a s a p o w e r ' s e r i e s ,

s u e h t h a t ^ ' / >

1 > + r. + •• - 3 /:• ' 1 2 8

a n d n u i i f e r i c a . 1 values o f SU') l i a v c b e e n t a b u l a t e d b y D a g g e t t ( 7 1 1

i ( 1 ' s a s s u m e d t o b e u n i t y a n d h q u a t i o n s [ 2 4 ] a n d [ 3 6 ] ; a r e

c o m b i n é e a n d i e a r r a n g e d , t h e . e x p r e s s i o n , b e c o m e :

id-2- • S ( c )

S o l u t D m o f t h i s e q u a t i o n f o r K i s a c h i e v e d i n a - m a n n e r sLiw-Uir r M t h a t o! t h e p r e v i o u s m e t h o d h u t . t h e . v a r i a b l e s - i n t h i s i n s t a n c e

a r e g e n e r a t e d v i a t h e S i : ) f u n c t i o n r a t h e r t h a n t h e Id rf> f u n c t i o n .

he ives I v e s ( 7 2 1 h a s d e v e l o p e d a m e t h o d f o r t h e

' ^ c i T f t t t ^ o n ^ o i e q u \ l i b r t u r n , c o n s t a n t s f r o m a c o n s i d e r a t i o n o f a

m o d i f i e d f o i - m o f t h e ' O ' s t w a l d D i l u t i o n L a w . T h e a c i d i t y c o n s t a n t -

i s e x p r e s s e d . a s . . ' >x

i\ • e • I i

X X

in which f is assumed to he unity and

[40] o = -/—-•:—- : --—>—

where A is the sum of the equivalent conductances of the ions at ionic concentration ac . A . is obtained ]|>y applying the abbrev­iated Puoss-Onsûger liquation [sec liquation [30]} to the ionized

i

part of the solute, such that

Ax ^ = A0 - S(A-.C/A Y ) J

Jin which S is the Onsagcr slope. Then Equation [50] 'may be re-written as

[42] & A V SlA-c/A;)^ = A, - — A'' 'c'^?- r~ V Kt[A0 - S(A-c/Ax)'I

i.

-Tbe-subst-i ttit-ion--of'-10--'-^A--^Ax^—for-f^2—lcnds-to—•— • '

.2 -. ,n-2A(A-c/Av> J

[43] A + S ( A ' c/A.. j 2 = A,,- A ' A' 1 0 • ' ^ . K trA 0 - b(A.c/Ax) "]

\ where A is the JJehvc-Iluckel coefficient. , • 1 \

By employing an approximate value of'A0, a linear least i

squares plot of the Ay- SfA-c/A^" and

f\? •c-10^A('A'c/'Ax) /!\0 - SfA-c/Ax)'- variables leads to the . generation of a new value of A 0 obtained from the intercept by-extrapolation. ,This, new value is incorporated into the iterative

45

process and the calculation is repeated. The'appropriate value, of Kt is accepted when the value of A/ Shows no improvement with­in 'predetermined precision limits. ' <

4 4

l-2c. •DIRECT' METHODS : THE DETERMINATION OF K t BY DIRECT' SUBSTITUTION OF PREDETERMINED An (VALUES

- ~ " ~ • • ,*!' \ : — - ; .-•

and mobility considerations both Sherrill and Noyés (73)-and Machines (74) defined the degree of ionization (a) in.dilute solutions of weak electrolytes as

V vei

fullv-ionized electrolyte at ionic concentration c where JV is the equivalent conductance of the hypothetical,

i * •

By employing an estimated value of fly obtained from A 0 and a theoretical equation for .A versus c which assumes'the electro lyte is strong (see Salt Method bclowy, Maclraies and Shedlovsky' (75) wore able to successively approximate the value of a to convergence from empirical equations. This improved value of a was subsequently used to calculate from Equation [24] with f, taken as unity.

In^a more extensive treatment, Robinson and Stokes" (76) divided the square^root term of the Onsager Limiting Law {sec Equation. [26]} by the factor (1 + K a ) * to allow for the finite

55 is the ion atmosphere constant of the Dèbye-Huckel Theory wliich can be put intfC" the form K 2' = 'B2ac where'ac is the ionic strength of the solution and B is a constant at given tempera­ture for a particular medium.

4 S

o , o size of the ions (aA) , which has an estimated mean value of 4A

(77). T h e r e s u l t i n g e q u a t i o n i s j •

1:45] •-• Av .= -A--- - • ^^T^n^l i 0 ' 1 + Ba(ac)

Ihe activity coefficient f± at the ionic concentration uc is now g i \'en by '

! f The value- of /w will not be veiy sensitive to the value ascribed , to me an lory1 size if the ionization of the weak electrolyte is not extens ive ( 7 7 ) .

• - j • .

The initial substitution of An for A^ in liquation [44] leads to ;m approximate value of a. Subsequent introduction of this value into Equation [45] yields an improved value of Irttera-

^ / _'~tion~'ol_thTs5~p~ ^ to. rapid convergence' of. a which-is '.then introtiticed into Equations 1.46] and" [24] to yield a value of - K T for "each concentrâtion-equivaïent conductance data point. The resulting K't values over the entire concentration -range are averaged and the associated standard deviation is calculated.

The Shecllovsky 11 Method. - This direct method was designed by Barnes (44) and Scott e_t al. (58, 78) as a simple modification oi, the Shecllovsky I Method described previously. A predetermined value of Afl is introduced into the Shedlovsky Equation {see

r 46

Equation [38]} and, as no Iteration is necessary, a value of K t

is generated for each concentration-equivalent conductance data point. As in the Robinson-Stokes fethod Jdiese-values-nf—K-t-arP averaged, with the resulting standard deviation being ascribed to" the error associated, with their measurement and calculation.

l-2d. THE DETERMINATION OF LIMITING 'EQUIVALENT CONÏXICTANŒS (An) FOR WEAK CLARBOXYLIC ACIDS (HB)

-Ihe-Sala^Methodr-^Drc^ complete and

association negligible in solutions oE sodium and potassium salts of weak carboxylic acids. A value of A 0 for a weak car-, boxylic acid can be obtained by an extrapolation procedure based on a 'modification pf Equation ['20-l-,>-namelv

•C47] ' '• A0(HB) =' A0(H+) > AQ(B"V

The calculation of A0(HB) .can be .achieved if the appropriate s ' . limiting transport numbers are available in existing tables' •["cf. (47) and. (48)].

Alternatively, A0(NaB) can be obtained by extrapolation of empirical conductance values at various concentrations of the _spdi..um_sal t„of„.tlie.rweak-acid This value-can-then-be-eomlvined with tabular values of the limiting equivalent conductances of the Na' and ll+ ions, such' that • •

'[48] A0(UB) = A0(H+) - A0(N7a+)'x:y!o(NaB)

This method has universal application for the determination of A0()1B), with the exception noted by Ives (42) that trie anion, B , have sufficient thermodynamic stability to maintain its mole cular integrity over the period of measurement.

48

iterative Methods. - The Indirect Methods discussed above' •J

may be used to determine values of. A 0(HB) by employing the ap-

propriate repetitive processes. Table IV compares values of _ ; 1&„ - r — ' •• '" ' A0(HB). for various weak carboxylic acids determined by the In­

direct Methods with those determined by the previously described

Salt Method. ' . • ,

• TheJShedlovsky IV__Method. - A statistical modification of

the foregoing Shedlovsky I iterative technique was devised by

Barnes (44) and Scott et al. (79) to determine 'the "best" value

of A0(IIB) based solely on a least squares treatment of the con-

centfation-equivalent' conductance data. The thermodynamic equil­

ibrium constant, K , and the standard deviation associated with

tliis parameter,.6, are calculated for a series of arbitrarily

chosen. A0(HB) values whose range falls on either side of the.

Jltr.ueLLAo (I"IB)_value This_calculationaiot-oiily--develops-a-func--— ' I. o

tional relationship between the averaged values and A0(1IB),

but more significantly, the standard deviation (<5) of the aver­

aged K1values may for any given value of A0(HB) be expressed as

a function of A 0 ( I 1 B ) . ' Tlie value of A0(HB) wliich occurs at the'

minimum of the curve resulting from a plot of 6 versus Ao(HB~) is

accepted as the "best" value of A0(IIB) on a least squares basis.

Sample plots of the Ô and (average)*q2ii£affl€ters versus

A0(HB) are shown respectively by Figures V and VI using data

derived from Table V. Values of A0(HB) calculated by this method

are compared with those calculated via the Salt Method and.thé '

Indirect Methods in Table IV.

TABLE IV '

A COMPARISON OF SQN1E WEAK QARBOXTLIC ACID LIMITING FQUR'UENT CONDUCTANCE VALUES ( A , V )

METHOD OF '

CALCULATION

S.ALT AfETHOD

CLASSICAL METHOD

SFEDLOVSKY I ÎETHOD

RTS fETHOD

SFEDLOVSKY IV METHOD

ÙVLŒILATTD BY VARIOUS .METHODS

v0 OF R-QizCOOIl (RE EEREN CE) * *

R .= H R = CF R = 4-MeO-C 6H,; R = > 4 - N O a - C 6 H

389 .6 ! (75)

590.'. 7

3 5 9 . 9

5 8 9 . 6

3 9 1 . 4

52)

3 7 9 . 6 (80)

3 8 3 . 7 (S3)

3 6 7 . 0

- 3 8 0 . 5

5 8 1 : 7

3 8 1 . 7

37-7.3 (81)

3 8 3 . 7 (85)

3 7 0 . 0

3 S 0 . 2

3 7 9 . 5

3 7 9 . 8

. 3 7 6 . 6 Û80)

3 8 3 . 0 T{S3j

3 7 6 . 5 i

3753.9 ;

3 7 8 . 9 ]

378 . 5

*A0 values are on Th^ncCTalit)' scale and have units of g cm Err1 equiv r - 1

7111 unreferenced values are taken from (44).

^ 50

TABU: V

SIEDLOVSKY IV RESULTS FOR THE CONCE$j |gp . CONDUCTANCE DATA OF IODOACETIC ACID AT 25°C_ rjAXByT^J^£n^

AN " AVEL^XGLTD'K^ X 10" A3YTSRE^^

375.0 ; 7.866 ' , 5.42 576.0 ' 7 . 7 7 7 4.96 377.0 • '".690 . • • '• 4.51 378.0 7:606 4.09 379.0 _ 7.522 • / 5:68 380.0" 7.441 • 5.29 381.0 . -. V j 7.361 ' ' 2.91 382.0 ' rh ; 7.282 , - ' 1/155 383.0 . 7.206 "N ,,2.20 385.0 • -7.056 ""\ 1-54 386.0 . ..;;.1"-"6.9S5 1.24 387.0 ' - 6 . 9 1 2 ' 0.94 ' 388.0 6.842 • 0.65 .38970— : "67773" " _ " 0.58 390.0 6.705 ' 0.12

- 391.0 6.640 . 0.15 392.0 6.574 0.37. 393.0 , 6.510 0.61 394.0 6.447 • 0.8.4 395.0 6.585 ' 1.05 400.0 6.090 \ ' 2.0 ?

\

"'Hie concentration-equivalent conductance data were taken from (42). K and-3 values are not quoted'for A 0 = 384.0 in the Table as these were omitted in the original [see (44)].

'" ' .'. V - FlétTRE V A PLOT OF THE DEVIATIONS (6) OF AVERAGED K t VALUES vs.

Aq FROM A SHEDLOVSKï" IV TREATMB^T OF IQIX)ACETIC ACID * DATA [TAKEN .FROM (44) ] ' ; .

/.h

A 0

52.

FIGURE VI

7 100

6 3 0 0 * 1 1 1 » 1 I I , I i 385 387 389 391 393 395

/ _ A 0

• A'TLOT OF AVERAGE!) Kr VALUES vs. Ap FROM A

DATA [TAKEN FROM Ç44)1

THE CALCULATION OF ISOTOPE EFFECTS

Previous Calculations, - Isotope effects can be directly determined through the use of Equation [48]'[c.f. (12)],

[48]' isotope effect = ^'t^9

. . . . . ' ^ ' .» d S

• \ . -

in which the themodynamic equilibrium constants of the' isotop-icallv substituted acids are obtained from the aforementioned

' ' ' " ' Direct and Indirect Methods oi calculation [c.t. (-56-, 43)], but less rigorous methods of comparison' have been emoloved (32).

The Shedlovsky III.Method. - The Shedlovsky Equation {see Equation [58]} has been modified in a novel'"way by Barnes (44) and Scott et_ al. (78) to directly calculate isotope effects. In tins method the intermediate steps of cqujEliVbrd dilation arc unnecessary. In Equation [5.8],;

[58] ' I 1 ^ A-c-fi-Sfz) A-S(c) A 0 Kt'iîy7

the'correction ternis 1/S(z] and f+/*S('zJ for the variables 1/A and A-c require a knowledge of A Q for their calculation. If a value of A0(H)* is available and assuming that A0(H) = A0(D)**>

*The'bracketed or subscripted H and'D notations refer to the res­pective protium and deuterium substituted', acids . **Thc validity and implications of this'assumption, are discussed in some detail below.

V ' ' • •' 54

both correction terms for the hydrogen and deuteri'ujri substituted acids may be calculated. The Shedlovsky varJablcsv'l/A''S(z) and -A-C- l+.'1-TS(z)- can-then -be determined-Tor- both :isotopic-acIds -to give '

. [ 4 9y , . ï; •_" + A(H).c(ir)-S('z),rf±2OJ) . .

A(41) -S(z) , A0(H) K- (1 \)\A0

2 (H)

and

[50] • 1 - = 1 ' + A(D) •c(D)-S(;z)n-lV(D)' _ '. - A(D);S('z)D. AC(D) ^ Kt(D)-A0

2(D) ' .

The slopes of the correlations, m^UI), and m (D) , are given by

[51] . ' mt(II) = l/Kt(H)A02i

and

[52] mt(D) = l/Kt(D)A02(D)

liencc , the isotope effect is'given by

' K CHT 'nr(D) [55] — = — -

. K-j. I'D). A mt0f) .

If a value of A0 is unavailable, the utility of this method remains undiminished, since the technique of variation of A 0

over a range of values falling on either side of the true value of A 0 .(described in the foregoing discussion of the Shedlovsky

TV Method) can lie incorporated into this treatment. A further refinement of this method results from a consider-

•—*—'• * — •"—^—— * 1 " j 1 — • " •' • — —-——— 1 1 1 — — c " " — • —

at ion of th*> i sot ope-effect " calculât ion-on a" "cell "by "cell""""' """" " basis.. If the valuf of A is- replaced by k-103/R in Equations 149] and [50], then the resulting slope values for a single cell (coll constant vf) can be algebraically reduced t

[54] mt 1 (IIJ = (V, *x 10a)7Kt(If) •a 0

2 ( I I )

and . •4' • :

[ 5 5 ] . - 111 ^ ( 1 ) ) = (k, x I D 3 ) V K ' t ( l T ) - A 0

2 ( D )

\ f Hence, the isotope effect value for a single cell will be

K t 0 ! ) , . m t

, ( D )

l l _ _ ^ t l 5 L ' £ t M _ _ ,

i

This implies that although values of i and A are required to calculate the 1/Sfz) and f±

2-S(z) terms (which are small), the influence of cell constant values and their associated errors may be largely excluded from isotope effects calculated on a single cell basis. • .

• 1 harnjis' (44) and Scott et ad. (78) have shown tliat the pre-o - " ' cision of the Shedlovsky III Method is higher than the precision associated with methods which compare thermodynamic equilibriimi • constants to determine isotope effects. They attribute the

increase in precision to the inscris i t ivi ty of the Shedlovsky" slopes to At/ i n the immediate range of the tine value of A() and

—Uae- eJaininat.ion of .eel 1 constant- values as major contributors' in the isotope effect calculation.

L J - Tables VI ;yid I'll illustrate the slopes of an i sot op i cal ly ' substituted acid pair lin. (II) -and in (D) ,y respect i vely 1 .as func­tions "of A , while Table Vl'Il shows the resultant isotope effects and demonstrates the reliability of this method. A comparu son

, of'th'e results of this method is made with those of other meth­ods of computing isotope effects in Table IX.

TABLE VI

SLOPE • [int(H) ] vs. A 0 FROM A SIEDLOVSKY III • *

TRËAWiNT OF. PHENI"LJ\CETIC ACID DATA LTAKEN FROM f44) ]

SLOgE [m (M)] x 10

CELL I CELLA IT .CELL III CELL JIV 'SELL V

1-.41S5 + 0 .0015 1 4155 + o. 'oois 1 41 74 + 0 0015 1 41.73 + 0 0015 1 4 1 3 : i 0 0016

1.41S4 + 0 0014 1 4155 + 0 .0015 1 4175 + 0 0015 1 4175 + o- 0015--" 1 4132 + 0 0016

1 .4185 + 0 0014 • 1 4155 0. jo 015 1. 4 1 7 5 + 0 0015 'l 4172 + 0 oms • 1 4151 ± 0 0016

1.41S2 + 0 0(114 1 4151 0 .0015 [

1 4172 + 0 0015 1 4171 + 0 0015 1 4130 + 0 0016

1 .4181 + •o 99414 1 4150 + 1

0 .0015 )

1 4171 + f) 0015 1 4170. + 0 0015 1 4150 + 0 0016

1 .4180 + 0 0014 1 4149 + ! 0 .0015

1 4 1 7 0 + 0 0015 1 4169 + 0 0015 1 4129 + 0 0016

1 .4179 ± 0 0014 1 414S + 0 .0015 I

1 4169 ± 0 0015 1 4168 + 0 0015 '. 1 4128 + 0 0016

1 .417° + 0 0014 1 4147 + 0 .0015 I ' 1 4168 + 0 0015 1 416^ + .0 0015 1 4127 + 0 0016

1 .417S + O...0014 1 414 7 + . i 0 .0015 1 4 1 6 " + 0. 0015 1 4167 0 0015 1 4126 + 0 0Q16

" V

TABLE VII

380

582

SLOBE [mt(Dj] vs./ An FROM A-'SlEDLCfSKY III ' I / :

TREATMENT OF /PIlEIBi'LAŒT I- 2 ,2 - d ? ACID DATA [TAKEN • FROM (44)] / . '

. ., . SLOPE [mf(D)] x 10 CULL I -, CELL II CELL III CELL IV CELL V

'374 1

376 '1,

378 1.

384 1

-386 1

388 1

390 1

4277 ± 0.0014

4276 ± 0.0014

4275 *+ 0.0014

4275'+ 0.0014 J 4274 ± 0.0014

4275 + 0.0014

4272 + 0.0014

4271 + 0.0014

4270 + 0.0014

1.4263 t 0.0014

•1.4264 t 0.0014 I

1.4261 Î^O.0014

1.4260 + 0.0014 i

1.4259 ± 0.0014 i • . ' I

1.4259 + 0..0014

1.4258 t 0.0014

1.4257 + 0.0014 '. I-

1.4256 ± 0.0014

1.4271 ± 0.0019

1.4270 ± 0.0019

1.4269 ± 0.0019"

1.4268 + 0.0019

J.4267 ± 0)0019

1.4266 ± 0.0019

1.4265 ± 0.0019

1.4265 + 0.0019

1.4264/+ 0.0019

1.4275 ± 0.0015

1.4274 +'0.0015

1.4274 + 0.0015

1.4575 + 0.0015

1.4272 t 0.0015

1.4271'+ 0.-0015

•1.4270 + 0.0015

1.4269 + 0.0015

1.426S + 0.0015

4255: ±

4254; t

4255; I

4252't 4251

4251

4250

4249

4248

0.0014

0.0014

0.0.014

0.0014

0.0014

0.0014

0.0014

0.0014

0.0014

AC­

TABLE' VIII

ISOTOPE EFFECTS CALCULATED VIA THE SIEDLOVSkY III TREAT?-tEN'T .OF

HŒNTWŒTIC ACID AND Pf-BAtACRTIC-Z ,2-d2 ACID DATA CTAKEs' FROM 0+) ]

CELL I CELL II CELL III CELL IV CELL V

574 1 .0065 + 0 .0014 1,0078 + 0 0013 i 1 0066 t 0 0017 1 0071 + 0 0015 ' 1 00S5 0 0014

376 ' 1 .0065 ± ô 0014 1 0078 + 0 ! 0015 i 1 O066 + 0. 0017 1 0071 .0 0015 1 0083 0 0014

37S 1 . 0065 + o 0014 1 0078 + 0 I 0015 1 0066 + 0. 0017 1 0071 0 0015 1 0083 + 0 0014

580 „ 1 .0066 + .0 0014 1 0078 t 0 0013 | 1 0066 + 0. 0017 1 0071 + 0 0015 •1 0083 0 0014

3S2 .1 ."'0066 + 0 0014 1 0078 + 0 1 0013 1

1 0066 t 0. 001^ 1 0071 + 0 0015 1 0083 + 0 0014

584 1 2R066 0 0014 1 0078 o- 1 0013 • 1 0066 + Ot 0017 1 0071 + 0 0015 1 0083 ' 1

v± 0 0014

386 1 . 0066 ± 0 0014 1 0078 + 0 0015 1 0066 ± 0 0017 1 0071 '+ 0 0015. 0085 '+ 0 0014

388 ' 1 .0065 + 0 0014 1 0078 0 1 0015 j 1 0067 0. 0017 • 1 0071 + 0 0015 ' 1 0084 + 0 0014

390 1 .0065 + 0 0014 . 1 007S + 0 I 0015 1 0066 t 0. 0017 1 0071 + 0 0015 1 0083 + 0 0014

t

TABLE IX

ISOTOPE EFFECTS CALQELAEED FROM VARIOUS TREATMENTS OF I -

CONCTNTRATT ON -LTJUIVATFAT TONTOCTANCE DATA [TAKEN FROM (44)]

ISOTOPE EFFECTS CLASSICAL

• 1.0045 ±0.0.007

ROBINSON

f] STOKES

1.0055

: 0. 0 0 5

i 1.0005

±0.005

1.0077 T ±0.002 -

SHEDLOVSKY

II

1.0054

±0.005

1. 004

±0.005

1.0076 ' ±0.0023 '

SHEDLOVSKY

III

" '1.0082

±0.0015

0.9975 • ±0.0017

1.0041 • ±0.0019

IVES

1.018 ±0.005

0.9936'

±0.005

- Q.9975

±0.005 o

)

\

\

^ ' n-lAPTER 2

P.XPERBENT/\L

2-1. GEM-: RAL I NSTRL ff -NTATI ON- . '

Nuclear magnetic resonance (n.m.r.) spectra were"recorded

- on Yarian A-od and f LA-100 • instruments "atr 60" M L : 'and TOO" M In" "res-pectively, with pi-obe temperatures ca. 40°C unless 'otherwise

speciLied. Chemical shifts are reported on their scale, i.e.,

relative'to the internal standard sienaj of tetramethvlsilarie. -

Infrared (i.r.) spectra wore-recorded on .Perkin-Elmo.r 237B or

225 spectrometers. -Each i.r.. spectrum was calibrated against •

a portion of a polystyrene spectrum. Melting points (m.p.) . »

were'cleterminoAI on a Fisher--Johns melting point apparatus.

Melting points and boilLng points Ch.p.) are uncorrected. Chem­

ical microanalyses were carried out by the Alfred Bernhardt

•Mikroanalytischcs Laboratorium, West Ceimaiiy.

X

2 - 2 . œNDUCl'ANŒ 1 NS'l'UUMRKTATTON . x

Conductivity Bridges. - The resistances of the potass i inn

chloride and aciu solutions - wero; measured by a neraJ Rrtuio "

• Impedance Comparator WO-R.I.C.) bridge. In the case of solution

oi phenoxyacetic and phenoxyaceti'ic -'2 »,2'-d? acids,, resistance mea­

surements from the G.U.l.C. bridge were compared with those ob­

tained 'at various frequencies (from a Jones-dosephs tvpe bridge

. (.M) manufactured; by Tins Icy Company. • A'description of the Tin-

sley and C.R.I.C. bridges is presented in Appendix I. 'Ihe Tin-

si e\- bridge auxiliary equipment and. the constant temperature

baths were constructed prior to this study.(-bl) by the Technical

Services Department, Memorial University of Newfoundland, and

their assembly is also described in Appendix I.

Tlionnoiiictry. - A Tins Icy Platinum Resistance Thermometer

(ytype S1S7" 11 ) calibrated by the.National Physical Laboratory

(Tcddington, lingland), in conjunction with a Mueller Temperature

Bridge (type 4772) , was cinployed to adjust the constant tempera­

ture bath to 25.000 ± 0.002°C. The balance point of the Mueller

Temperature Bridge u"^detcnuinod by a Leeds and Northru'p DC

Null Detector (9S34 ) .

A Honeywell recorder was used J g tt fîtor the bath'tempera­

ture .over long periods. 'The recorder served as a detector in a.

I'.heatstone Bridge circuit, with a Fcnwal Thermistor serving as

one ami of the bridge. Live resistors (>2.57 to LOkR) were used

to control the sensitivity of the recorder1,- The 625fA resistor

gave a sensitivity ot 0.02°C for .10 small divisions on the re­

corder chart paper. • \ ., _

During the initial study of one of the acids, namely! \

phenylaéetic,acid, .the value of the equilibrium/constant deter- •:• mined led to the conclusion that the bath temperature was ad-

\. •

justed slightly above 25.000°C. A new Tinsley Platinum Res is- , \

tance Thermometer indicated that the bath temperature was 25.051

+ 0.002°, and- the temperature was readjusted to 2 5.000 ± 0.002°C.

The former Platinum Resistance Thermometer was recalibrated ~ \ : • : I

at t\ie National Research Council oi Canada Laboratories fOttawa) .

The temperature of the bath was me^-hred with the recalibrated

thermometer and found to be 25.D00 ± 0.002°C; hence the two

Platinum-Resistance Thermometers were in excellent agreement.

After monitoring the hath for three months with the Honey­well recorder, one of three Beckman thermometers, calibrated

against the Platinum Resistance Thermometers, was used as Aa

continual check on the bath temperature instead of the recorder

The Beckman thermometer calibration was periodically checked

against the PIatirain Resistance Thermometers throughout the.re-•' & • '

mainder of the studv.

Conductivity colls. - The conductivity cells were'construct

ed with shiny platinum electrodes in three differenf designs A see

Figure VII). The cells were designed to give cell constants'

FIGURE VII . 64 • DIAGRAMS OF THREE* TYPES OF fTET.T.S

) Shedlovsky- (55) c e l l design

' A \

(b) Kraus (86) c e l l design

( c ) Robertson ( 8 7 ) c e l l d e s i g n

ranging from 0.08/to 0.37 cm"'. The bulk of the Measurements

were accomplished using cells of the'Shedlovsky type (85), .like ~thos^

Measurements in other t -pes of cells kscc Figures ATI (h) and V Vl'I(c)] were made in conjunction with these for purposes of comparison. • " -

Cleaning procedure. - The cells were washed initially with warm eth'anol (95 j) and rinsed with '"conductivity water" (see preparative description below, p. "<>). They were filled with aqueous hydrofluoric acid (c/a. 3° ) for 5 mm and. rinsed with conductivity water. They were 'subsequently treated for 3 days with concentrated nitric acid ca. 100°C. The nitric acid.treat­ment was repeated four- times., and the cells were then filled-with hot (ca. 100°C.).conductivity water. *?hc cells were rinsed

and refilled'dailv with fresh'conductivity water for 10'davs • • .7 '. . / • ' . " while the temperature was kept near the boiling point.

v/Sw^Rient to this treatment the resistance of the conduc-tivià*$#? eilft nN the cells remained constant to 0.01% over a peidotl»0£''1 „ul, indicating that the removal ol surface ions was essentially complete. The cells'were then-conditioned with three solutions.of potassium chloride (ca. .1 x, 10"3M) for 72 h • (total) ,' and subsequently treated twice with a solution of purified ' ' \ phenyl acetic acid (ca. . 5"x 1073M) for 48 h (total). lAollowing the second treatment with the latter, the resistance of a

66

freshly prepared solutron of purified pnenylaceti'c acid (ca., 5 -x 107 3M) renlained constant for a 24 h period. . ,r.

Taier c-fe , except' the- hydrofluoric-acid' treat-ment, was applied to all glassware used in the preparation of ' solutions for conductivity measurements.

j?

. 6 7

i ' -, ' • *

2-3.- 4\n;[UA6s .

P o t a s s i u m c h l o r i d e . - ( i ) A s a m p l e ( P i . s h ' c r y S c i e n t i f i c ;' A . R . .

. — ~ — : ~7 _ ( I r a d p l , o i - p o t a s s i u m c h 1 o r i d e " ( 1 0 ( 1 g ; 1 . 3 4 - m o l e ) w a s p r e c i p i t a t e d A

f r o m a s a t u r a t e d , c o n d u c t i v i t y w a t e r . s o l u t i o n b y t h é a d d i t i o n o f

p u r i f i e d e t h a n o l . [95V) - a n d c o l l e c t e d . T l i i s p r o c e d u r e w a s r e p e a t e d

f o u r t i m e s . T h e s a l t w a s t h e n f i l t e r e d , w a s h e d s e v e r a l t i m e s

w i t h - p u r i l i e d e t h a n o l ( . 9 5 1 ) a n d d r i e d i n v a c u o a t 1 1 0 ° C f o r t w o

d a y s - . T h e . s a l t w a s .then powdered i n a ' c l e a n a g a t e m o r t a r a n d

d r i e d a n a d d i t i o n a l t h r e e d a y s i n v a c u o a t 1 1 0 ° C . T l ) e p u r i f i e d * »

p o t a s s i u m c h l o r i d e w a s s t o r e d o v e r s i l i c a g e l i n a v a c u u m d e s i c ­

c a t o r . ,

( i i ) A s e c o n d s a m p l e o f p o t a s s i t o n c h l o r i d e ( 2 5 g ; 0.355'

m o l e ) w a s p r e c i p i t a t e d f r o m a s a t u r a t e d c o n d u c t i v i t y w a t e r s o l u ­

t i o n b y t h e a d d i t i o n o f c o n c e n t r a t e d h y d r o c h l o r i c a c i d . T i m s

""pT^CH^dhrc w a s - r e p e a t e d t w i c e , a n d t h e - s a I t W a s t h e n t r e a t e d i n

t h e m a n n e r d e s c r i b e d i n ( i ) a b o v e . • - . »•

/ ( i i i ) . A t h i r d s a m p l e ( A l d i u c h ; o p t i c a l l y - p u r e ) soi p r / t a s s i u m

c h l o r i d e ( 2 5 g ; 0 . 3 3 5 m o l e ) w a s t r e a t e d b y t h e p r o c e d u r e o u t l i n e d

i n ( i l a b o v e .

P h e n y l a c e t i c a c i d . - A s a m p l e - ( B r i t i s h . P r u g H o u s e s ; R e a g e n t

G r a d e ) o f p h e n y l a c e t i c a c i d ( 5 0 g ; 0 . 3 6 7 m o l e ) w a s . d i s s o l v e d i n

a n a q u e o u s s o l u t i o n o f s o d i u m h y d r o x i d e ( 2 M ) p r e p a r e d f r o m ' c o n ­

d u c t i v i t y w a t e r a n d s o l i d s o d i u m . h y d r o x i d e . T h e . s o l u t i o n w a s

•••V

doubly i lltered and the acid was precipitated•from the cold

solution, by the dropwise addition of/da slight excess, ol hvdro-

—dalorlc-acj d—(-2M-)-!—#he^e*d-wHs^^l4eet-ed^^

the procédure was repeated with do'uble'filtration after dissolu-tion. Ihc acid was collected and recrystal lized from purified C S S J ben errfe-petrolcuiii ether' [jcp. '30-60°C) . After subsequent "collection and air-drying', trie sample was sublimed (ca. dO°C; ' • ••] mm HgJ. After the recay/stal Ihzat i on and .sublimation proced­ures had been repeated four time's, the. acid was subjected to y

/ three successive sublimations. The'malerial was crushed and

A'/ > " dried in vacuo over silica pel for 48 h.

( i i j A sample q'f the latter lb gy 0.0367 mole) was zone--refined (21 passes/"over 7 days), sublimed and dried in a manner / similar'to the above, in.p. 76.2 - ~(i.6°C Mit. m.p. • "o."°C (89)1.

/ ' ' '

Phenoxyacèti.c acid. - A sample * Hastman Organic Chemicals;

99+';,) of phenoxyacetic acid (1O0 g; '0 .'657 mole) d issol ved-': in , i

'aqueous sodium-hydroxide (500 ml; 2M) was washed with three por­tions (200 ml total) of diethyl ether. The aqueous Paver was acidified with a slight excess of hydrochloric acid (520 ml ; 214), and the volume of the solution was reduced (ca. 200 ml). The solution was cooled to ta. 0°C and the resulting precipitate was collected. Seven alternate recrvstallizations fconductivity water) and sublimations (96 C; •"! mm llg) -were then carried out on the material, :md subsequent to an additional sublimation,

.: . ' \

. . - - ' \

1

the material vais crushed and dried in vacuo o ayr silica eel Tor •n2 h, m.p. 99.0 - 99.S°0s-[lit. in.p. 99 - 100 9""(90) ] . .

{.Til mole), dissolved in dt itrrripin oxide ('99.75':,; 50 ml) and •triethylamine '(150 c ; 1.48 mole)', was. sealed in a glass tube aiu heated to 125 0 for 24 h. The water and 'excess triethylamine were'removed hy distillation ujider reduced pressure and new quantities of deuterium, oxide ( 50 ml) and tri ethylamine ( 1 0 g; 0.099 mole) were added to-the residue. The mixture was again heated to 125°C for 24 h. .This procedure for isotopic exchange was repeated four times, and the Iinal residue was purified in

a manner similar' to that for phenoxyacctic acid, m.p. 99.1 -o ' -99. 5"C. Several n.m.r. spectra- (CDCl3J indicated that doutera -

tien at the methylene position was not less than 98.27,. The _percent_deutcratipn-.was-.compiu;ed-d~>y--com methylene signal with that of the methyl group of acetonitrilc (17), introduced as a standard.

r Chloroacetic. acid. - Purified (91) reel phosphorus (6 g;

D.048"mole) and glacial acetic acid (150 g; 2. 50j mole) 'were_ " • " ' / ' o mixed in a. round-bottomed ila'sk, weighed and heated to 100 C. Chlorine gas was bubbled through the reaction mixture for a period of 5 h and the temperature was maintained at,105 - 110°C Ifpon cooling,, the flas-k and contents were weighed, and the pro­cedure repeated until the weight of the reaction mixture had

\ . . . • • '70

acetic acid (107 g; 42v yield), b.p. d88 - 190°C and in.p. .56.1 -58.5°C [lit. b.p.' and m.p. arc 1S9.4°C and 65.0°, respectively (95)]. , ' ' ' ' A

N.m,r.4spectra (CD3COQ1)3) were recorded as a measure of the • pur.ity of tire cliloroacetic acid. A comparison of the absorptions at V 0 t (CI1 of dichloroacetic acid) and 5.9 t (CD2 of chloro- • acetic acid) indicated the "distil1 ate,was.95.55 pure.

The crude sample of chloroacctic acid was reci vstal lized ' • "• o • " >

three, times (CHC13) , in.p.' 59.2 - 59.6 C, and found to be 96", • • ^ • ,

pure by n.m.r. analysis. Ihe acid (50 g; 0,529. mole) was melted iVndc?az- ^ (ca. 0.1 mm .Hg) in a sublimation apparatus and the temperature was slowly raised to 62.5°C. • Temperature and pressure were maintained for 48 h, after wliich the sublimed material was recrys'tallizèd (Cl ICI 3) , m.p. 60.0 - 60.5°C. .This process was repeated but n.m.r. measurements indicated that it. difl not increase the purity oi the chloroacetic acid beyond QS- V

. . .

^ Sublimed chloroacetic acid (40 g; 0.423 mole), recrystall-

izecl from chloroform, was heated to ôO^^C; nitrogen was contin­

uously -bubbled into the molten material- and the temperature was

raised 0.5°C at hourly intervals. After .5* h-the acid was cooled

X -

increased by 80 g (92). The reaction mixture was distilled, and

the fraction collected over the b.p; range of 150 200°C vas Re­

distilled twice,.the final distillate beinp colourless cbloro-

and recrystallized (CHC13)m.p,. 60.9 - 62.3°C. N.m.V. measure-Cements indicated that this process failed to raise the' purity of 'the acid beyond 99.6°.. This process was .repealed'imti'l. crystals

—began -to -form at -62-.-5- C.-. ---The temperature was then' raised '"to1"""'"" " 63.5°C and the liquid was allowed to cool slowly. Mien two- \ -thirds of the'material solidified, the' remaining liquid portion was immediately decanted from the newly formed crystals'. •

This fractional crystallisation procedure was repeated twi-ce* and the remaining needles (4 g; 0.042- mole) were washed with cold chloroform and dried in vacuo,.m.p. 63.0 - 63.2°C.

.' N.m.r-. measurements- could not detect the presence o£ .dichloro-acetic acid in a sample of the required acid. This material was then cone-re fined (21 passes over 7 days), 'recrystallized from spectroscopical ly-purc* chloroform and sublimed (60°C; <1 mm'Hg). The acid was crushed and dried in vacuo'over silica eel for 72 h.

• Ghloroacetic-2 ,2-d2 acid. . - ChloroaCetic-2,2-d2 acid 'was prepared and purified by following the procedure outlined above for chloroaeetic acid, 'except tiiat glacial acetic-2 ,2 ,2-d3 acid was substituted for'the prot inn acid.'" An n.m.r. spectrum (CIV COG. tha

-» COCD3) of this material, (rn.p. 62.9 - o5.5°C) indicated not le zfyan 98. 7->, deuterium at the methylene position.

' Phen ithi ogiveoil 1c acid. - A sample (Aldrich; 99+1) of ' j ' ' •

. ri?râiylthioglycoll ic acid (100 g; 0.595 mole) dissolved in

aqueous sodium hydroxide (500 ml; ZMj was washed with diethyl '

ether (200 ml total), and the solution was acidified with a

slight excess of hydrochloric acid (520 ml; 2M). A'white precip--^tatc^of"" was- collected- subsequent- to-reduct ion" of -the""' ""' solution volume (ca.'200 ml).and cooling to 0°C. The air-dried material was recrystallizcd . (conductivity water) and sublimed (61°C; <1 nun Fig) . The material was subjected ,to five alternate reciysta 1/1 i nations (cojidu rlvi.tv watdr) and-sublimations 'followed by tw-o .additional sublimations. The acid was crushed and dried 'in vacuo over silica-gel- for 72 h, m.p, 62.8 - 65.5°C [lit. m.p.

• 5 ~ 62.5 - 05.5UC f 46) d. . . " j ij v

Phenyltfiioglycollic--2 , 2-d: acid. ' - Phenvlthioglvcoll ic acid (150 g; 0.892 mole) was added to deuterium oxide (90.75";

.'.7, ( ' • '

50 ml) raiid* triethvlamine (125 g; 1.235 mole), and the resulting soWionVa/ heated in a sealed glass tube at ]25°C for 24 h. 'fhe water and excess tiuethylajni.no were removed by* distillation under reduced pressure, and a second exchange was carried out in a iJirnmer similar to the first using fresh deuterium oxide (50 ml) and' t r i et hy lamine - (20, 0.198 mole) w'lth the partially exchanged acid. Three further exchanges followed by recover}' of the acid yielded a material which', on purification by recrystallization and sublimation (see procedure for protium acid),- had'a m.p. 62.5 - 65.5 C. An n.m.r. spectrum (CD3COCTP )' of the acid indicated not less than 97.8-% deuteration at the methylene position.

Phenylisulfinylacetic acid. - Purified phenylthioglycollic 'acid ("53.8-g; 0.206 mole) was dissolved in labs o lute ethanol at 0 - 5°C amf 50° hydrogen peroxide (24 g; ca. 0.22 mole) was added ' dropwise to the solution. After standing for 2 h, the excess hydrogen peroxide, ethanol and water were-removed by distillation under reduced pressure. -The oily residue was taken up in hot. benzene-ethyl acetate (5:1 by volume) and on cooling yielded white prisms of phenylsulfinylacetic acid (20.8 g; 815 yield), m.p. US.5 - 110.2°C [lit. m.p. 118 - 119.5°C (94)]-[Found : C, Ï2.24; II, 4.37; O,|"6.01.5 S, 17.52. 'CaH003S requires C, 52.16; 1 1 , 4.39; 0, 26.06; S , .17-405].

The acid, had three absorptions in its. n.m.r." spectrum (CTI3COCD3) , a singlet at 6.1 T (Oh) / a broad singlet extending from-3. 5 x to 5.4 x (Oil) and a multiplet from 5.0 T to 2.5 T

(protons attached to the aromatic ring)'. The intensities of. the signals at-6.1 T and 2.5 - 2.1 T were in the ratio of 2 to 5. An i.r. spectrum (Q-ICT3) of the acid showed strong absorptions Tor "the, SO stretching vibration at 1028 cm'1, and the carbonyV' stretching vibration at 1/750 cm-1. The acid was recrystallizcd six times from purified (95) ethyl acetate and dried in vacuo' over . silica gel for 72 h. . • -,

IdienylsulTinylace_tic-2 ,2-d2 acid. - Purified phenylsul finyl-

acetic acid (56.8 g; 0.200 mole) was - dissolved in deuterium" oxide-*/"

( 9 9 . 7 5 Ï ; 1 0 0 ml) and stirred for 1 0 h at 50°C. The deuterium oxide was removed by lyophilisation and a fresh portion ( 1 0 0 ml) was added. The exchange process-was; repeated'six times ..and tjia -residue' was taken up'in boiling anhydrous benzene-ethyl acetate ( 3 : 1 ) . Phcnylsul I'inylacetic-Z,-2éd.-, acid ( 2 7 . 6 g; 751 vield) crystallized from the cold solution as white prisms, in.p. 1 1 4 . 5

- 1 1 5 . 0 C C . This material was rccrystallized six times from pur- -i-ticd ( 9 5 ) .ethyl acetate and dried in vacuo over silica gc ! for 72 h. • . •. > - : -, ;•• • • . ^

• Phcnylsul f" inylacct ic - 2 ,2 -d.- acid had two absorptions in its n.m.r. spectrum (CT3COCD3) , a broad singlet at 3 . 5 - 3 . 4 T (Oil) and a multiplet from 5 . 0 ' T , to 2 . 5 i (protons attached to the aroma t ic- ring). This assignment was partially confirmed by J

marked increase m the intensity of the former absorption after a small addition of trifluoroacetic acid. .Although the amplitude 'oT" ddfe spectrum was increased, the presence of protons in the methylene position could not be detected. An l.r. spectrum' (CHCI3

ol the acid was similar to that, of phenvlsulfinylacetic ,acid with the exception of a broad shoulder in the'region of 2 3 5 0 - 2 2 0 0 a i r

Phenylsulfonvlacetic acid. - laatified phenylthioglycollic acid ( 3 5 . 8 g; 0 . 2 0 . 6 mole) was suspended in water ( 1 5 0 ml), and sodium carbonate ( 1 0 . 6 g; o.HO mole) was slowly added to the -sus-pension with stirring. After the evolution of carbon dioxide, potassium permanganate ( 3 1 . S g; ca.- 0 . 2 0 2 mole) dissolved in water

(800 ml) at 0 C was added dropwise, and the solution was stirred

for 18 h. The manganese dioxide precipitate was removed by fil­

tration through "Colite", and the clear aqueous filtrate was

acidi fied vu tir hydrochloric "acid"""(6M)".' "' The "solution" was then"

extracted four times with diethyl ether,(400 ml total) and the

combined ethereal extracts were dried over anhydrous•magnesium

.sulfate. The solvent was removed,by distillation under reduced

pressure, and the syrupy residue was taken up in a minimum' of "S • r

liot .benzene. On cooling, white prisms of phenylsulfonylacetic

acid (27.5 g; 683 yield) crystallized from the mother liquor.

This material was alternately recrystal^ized from purified (88),

anhydrous benzene and sublimed (102°C; <1 mm Hg) six times, fol1

lowed bv an additional sublimation, in.p. 113.8 - T14.2°C [lit.

m.p. .11,5 5 - 114°C (40) ] [found: C, .48.16; U, 4.04; 0,'31.86;

S, 15.85. C8HoO,(S requires 0^ 47.99; II, 4.04; 0, 31 .96; S,

~T670T37j7 Tlfe VTTcid'TCT in vacuo over silica gel

for 72 h. J An i.r. spectrum (Nujol mull) of phenylsulfonylacetic acid.

showed strong absorptions at 17305 an - 1 and-1170'cm71 due to the

respective asymmetric and symmetric stretching vibrations of the

SO2 group, and at 1715 cm"1', the carbonyl stretching frequency.

"The acid had three absorptions in its ri.rn.r-. spectrum (CD3COCD3) ,

a singlet at 5.7 t (CTL), a, broad • singlet extending from 5.0 T

to 4.6 T (Oil) and, a multiplet at 2.4 - 1.9 T (protons attached to

the aromatic ring). The intensities of the absorptions at 5.7 x

76

and 2.4 - 1.9 T were in the ratio of 2 to 5.

Phenylsulfonylacetic-2,2-d2 acid. - Purified phenylsulfonyl• •'- acetic acid -(40.0 g ; 0.200 mole) was treated in a manner similar to the exchange-process outlined above for phenylsulfinylacetic-• -2,2-d2 acid. 'Hie resulting phenylsulfonylacetic-2,2-d2 acid was alternately recrystallized and suolimed in the manner described-for its corresponding protium acid. The white prisms (31.5 g ;

Vsi yield) were-crushed and dried in vacuo over silica gel for 72 h, m.p. 113.6 - 114.0°C. • ' ' ^

An i.r. spectrum (Nu)ol mull) of'the acid was similar to that of the protium acid except for. the presence of a broad shoulder in the 2575 - 2200 cm - 1 region. Tire compound showed two absorptions in its n.m.r. spectrum (CDaCOCTb), a broad sing­let from S . 'O^T to 4.6 T (CHI) and a multiplet from 2.4 t to 1.9 T

— (protons-attached-to^ the •'aroroatic~ring)T'~The~presence~of "pro tons-

'at the methylene position (5.7 x) was detected, but the' signal intensity was inseparable from base line noise.

Conductivity water. - Tap water was fed through a Fid flo commercial water filter and then distilled by a Corning AG-lb still (maximum distil lajt ion rate, 1 Vh) . The distillate was collected in a glass reservoir (capacity of 12 gallons) and fed via a glass siphon into a Barnstead still (distillation rate, 0.5 'gallon/h). This still , 'with a borosilicate glass condensing

ysystem, was designed to produce a water disti ] late of not more t

than 0.001 parts 'fier million (ppm) total solid content, with .-electrical resistances ranging from 1.5 yTTmill ion-ohms per cm3. -Ewo~t-hree~ne^^ (total -capacity- of - 20--]) •

fitted wjtli Teflon joints were used as conduct i vity water -reser­voirs. Th.ese flasks were previously cleaned according to the pro­cedure described above, p: OS. g

A purified nitrogen 'atmosphere (see following subsection,' this page) was introduced into the Rarnstead 'still prior to and during distillation. A continuous,flow of nitrogen was maintained over the water pistillate in the reservoirs at all tunes. The ;1

water was siphoned witliout further treatment through glass and Kalgon tubing to the apparatus used for transferring the conduc-« , • - • . tivitv water to the solution flasks (see Figure VIII). • • . •

I'.'hen in continual use, the Barnstead still was drained and ref i 1 led da i lv_wi.th ..f reshl v~'d i s til led-Kater-r-as-werc-1 hc~two~con~ ductivity wafer reservoirs. ' The specific conductivit>r of the fy

water ranged from (1.7 to 5.5) x 10"752" 'cmAv and water having a higher specific conductivity was discarded.

Ni t rogen pur if i c at i on. - Nitrogen (L-grade, Liquid Air of Canada) was successively led through cleaning towers with sintered glass bubblers containing concentrated sulfuric acid, aqueous sodium hydroxide (501) , aqueous barium chloride (saturated solu­tion) and conductivity water. Empty towers were located between the various towers containing;sfoiutions to eliminate possible

FIGURE VIII Çal - - 78' r '"' A DIAGRAM OF THE CELL FILLING APPARATUS -

"O ID

.5 .«? n : •

r e a c t i o n s . b e t w e e n t i j e s c r u b b i n g r e a g e n t s . S ^ a r a t c o u t l e t s f r o ' n i

t h e ' n i t r o g e n t r a i n t o ' t h e a t m o s p h è r e w e r e ^ f n s t a l l e d i n t h e N a l g o n

- t u b i n g , , u s e d - t o - j o i n ' s t l i e t o w e r s . — • D u s t - i « l ' r t i c l e s - u - c ' ' ' e - t • h i p p e d " b y -a -

f l a s k p r i c k e d w i t h class w o o l l o c a t e d / a t t h e e n d o f t h e s y s t e m .

T h e p u r i f i e d n i t r o g e n w a s l e d t h r o u g h N a l g o n t u b i n g t o t h e B a r n - ,

s t e a d s t i l l , t h e c o n d u c t i v i t y w a t e r r e s e r v o i r s , a n d ' t h e a p p a r a t u s '

u s e e f o r t r a n s 1 e r r 1 n g t h e c o n d u c t i v i t y w a t e r ' t o - t h é , s o l u t i o n ..

P r e p a r a t i o n o t p o t a s s i u m c l r l o r i d e s o l u t i o n s . - P o t a s s i u m

c h l o r i d e s o l u t i o n s f o r c o n d u c t i v i t y m e a s u r e m e n t s w e r e p r e p a r e d b y

w e i g h t ( c o n c e n t r a t i o n s e x p r e s s e d i n m o l e / 1 O O P 'g , o f w a t e r ) - i n the

f o l l o w i n g m a n n e r . A c l e a n , o v e n - d r i eel ( 11 0 'O f l a s k - ( ' 3 1 ) w a s

w e i g h e d o n a . S t a n t o n ( l l . P . J . m o d e l ] t w o - b a n balance a g a i n s t ' ca 1 i -

h r a t e d ( N a t i o n a l B u r e a u o f . S t a n d a r d s , W a s h i n g t o n ' ( N ^ B . S . ) ] , s t a i n ­

l e s s s t e e l ^ w e i g l i t s ( s e r i a l n u m b e r . d'OS S ) . - T h e f l a s k w a s ' t h e n c o n -

n e e t e d t o t h e I i 11 i n g a p p a r a t u s s h o w n i n F i g u r e V I 1 1 . • a n d t b e r o u g h l )

tJushed with purified nitrogen. With continuous nitrogen flushing, t ' '• - • ' ' •

c o n d u c t i v i t y w a t e r w a s l e d - i n t o t h e f l a s k b v g r a v i t y f l o w , f r o m t h e

i r e s e r v o i r s t h r o u g h a g l a s s d e l i v e r v s v s T e m . T h e f l a s k w a s ' w a s h e d

y, ' ' ' ' ' ' w •

t w i c e w i tli c o n d u c t i v i t y w a t e r t o r e m o v e a n y ' s u r f a c e i o n s ' o n t h e

g l a s s . P r e s s u r e e x e r t e d b \ \ t h e n i t r o g e n f l o w i n t o t h e c l o s e d

s y s t e m w a s - e m p l o y e d - f o d r i v e t h e w a t e r f r o m t h e f l a s k t h r o u g h a

N a l g o n - d e l i v o r y ' t u b e '.î ,tj a c o n d u c t i v i t y c e l l . A t h i r d w a s h i n g . , w a s

o n l y - u n d e r t a k e n . i f t h d ' s p e c i f i c c o n d u c t i v i t y o f t h e w a t e r f r o m

the second-washing was above 3.5 x 10"7py'cm"1. The flash, was

then filled wi.th'water of known specific conductivity, capped and

TCT'.'etghedT""y— y _ ' • 3.7)__].'_.''.J...._ '

A clean, oven-dried vial containing a weighed sajuple. of

potassium ch-lqridc was dropped into the "'solution flash. The

potassium'chloride sample was weighed by difference on a Stanton '

CM.C.I ,.3. model) two-pan .analytical balance against calibrated

(N.H.S.l stainless' steel 'weight's (SS 5487)'. 'lire vial was manipu­

lated with clean,, diy forceps throughout the entire .procedure.

After homogeneous dissolution of -the potassium chloride

was achieved by vigorous shaking, the flask was reconnected toy

the filling apparatus and flushed with nitrogen. Pressure exerted

by the nitrogen flow into the closed system was again used to

force the potassium chloride solution into a cell attached to the

-filling-apparatus I'ruor-to-bcing-fi lied-,—the-eeH-was-f lushed—

with nitrogen and washed with ca. 400 ml'of the solution. The — . \ ' ~y

cell was subsequently filled, capped and placed in" the constant temperature bath. This procedure* .was repeated' for each of t\he cells used in the conductivity measurements of the potassium .chloride solution. • ' . ' •• -,

All g 1assware - and cells were'thoroughly washed with conduc-* . - '-*v

•ti'vity water fob-lowing the measurements. The glassware .was oven - *

-dried anil the eel Is wore filled with conductivity water.

. .' - • V A 82

, Preparation of acid solutions. - Solutions of 'the acids '• " ! were prepared following the procedure outlined alcove for potassium chloride solutions. An exception1; to tlie latter was the wcirhinc .. • . . . . . ^ t,. v-.t... . i ««». w — ^ - — — — — — • — - ' j ^ •••

procedure used for chlpvoac< J d''.chlor.oaKetic-2 ,2 -d2 acids, hue to the IrvgroscopH* jiiîfture.'D'llçtKèse .acftfet-ij'.e enti re • weighing procedure. wasNcarriéd out iifcâ%%'r5 p&.'Êiïîslj ff.i-with drv nftroecn. . , , . ' • - \ •••• &\ > « . Ibis precaution proved satisfaCvfai* «rt&'Wéiqht of''the samples did not appear to jncn-ease \irteg ie procedure.

• '- " ' .• "<? M^.f^'-^ - . ' Resistance measurements. - Re^^^fàee^pf 'solutions were. A i

recorded thirty-five minutes after'the cell entered the constant . •>_'- -, ' /SA 4 •

temperature bath. In some cases res i s tancé.measurement s were repeated .after the cells had remained vi^r the bath for a further ' period of time, for both potassium chloride and acid solutions , • resistances- were found. to y?han.çè less, than 0 .11 over a period of

iŒSin;i's

.VI . ' CF.LL CONSTiWrs • . • : : ^ . . . c, . •

C e l l c o n s t l i n t s . - C e l l c o n s t a n t s v / e r e d e t c m i n o d u s i n g , i n ­

d e p e n d e n t l y p u n f i e d s a m p l e s o f p o t a s s i u m " c h l o r d d e " [ d e s c r i b e d

a b o v e , p . o " ) . I l i e w e i g h t s o f t h e p o t a s s i u m c h l o r i d e a n d t h e

• s o l v e n t i n a i r w e r e c o r r e c t e d f o r h o u y a n c y e f f e c t s u s i n g t h e e x ­

p r e s s i o n ' . ' • .

i n w h i c h M i s t h e t r u e m a s s o f a b o d y i n V a c u o , K i s t l i c w e i g h t -

o T ^ t r i e b o d y i n a i r , " b i s t h e d e n s i t y o f t h e s t a n d a r d " / e i g h t s , - ;.

i s t h e d e n s i t y ,-, f t h e b o d v , a n d ,•' i s t h e d o i v - i t v o f a i r a t r o o m

t e n q i c r a t u r e " c f . ( 9 6 ! J . , s

. S i n e e t h e s o l u t i o n s w e r e ' p r e p a r e d o n t h e m o l a l i t y s c a l e ( m l

1 t h e e q i i a t i o n r e l a t i n g t h e e q u i v a l e n t c o n d u c t a n c e o f p o t a s s i u m a m

d i l o r i d e t o c o n c e n t m a t i o n i s g i v e n u s i n g t h e m o l a r i t y s c a l e JM1>.

: o n v e r s i o n b e t w e e n t h e s c a l e s w a s r e q u i r e d ( 9 ~ l . ' D u s w a s a c h i e v

i s i n g t ! i e e x p r e s s i o n •

5 S I I V , , V 0 V 0 ° •

i n w h i c l v V j< t h e v o l l i m e o f t h e s o l u t i o n , , \ ' 0 i s t h e n u m b e r - o f

i n o i e s o f w a t e r , N, i s t h e n u m b e r o f m o l e s 6 f - - m a s s iurn c h l o r i d e

a n d V.-,J i s t h e v o l u m e o f o n e ' m o l e o f w a t e r a t 2 S ° C . T h e d c n s . i t } '

o f w a t e r . w a s t a k e n a ; : i ) . ' . i o ? " " . " ) g m l ' 1 a t t t i i s t e m p e r a t u r e . T h e

mblal volume 0i , was ' obtained fi-om

\ L591 ' 0, . . sA...26..J5.t__±—?^Ç3-lr-\±~~ = ;

in which c is the approximate concentration of the solution.

'Die specific conductance of an electrolyte in solution,

, L('s)» l s defined in bqbation ;d7], which rearranged is

in which A is the equivalent conductance and c is tlie molar con­centration. 1'lie true specific conductance, L, -is obtained from

[61] 'V L '= hs) ' L ( w ) s '• '

wliere Lv.j", is the specific conductance of the watpr. , *

"'life equivalent" conductance o£ each concentration of potass­ium chloride was computed from the following equation .proposed bv 'f-'uoss C9S) , - • - r '

r62] • A = 149.OA - 94.65 ch + 58.74 c log c +' 198.4 c

By substituting the computed vaj.ues of A- and c into fqua-tion [69], corresponding' values of h'we>re derived from Equation

[61]. "Cell .constant values were"then obtained from equation [16] /• » rearranged to ' '

8 5

T63] ' i; - LR " ' . - ' .

where K I S The cell constant .and R is the resistance in-ohms • The cell constants Iwere determined "subsequent to the cell

cleaning curd conditioning previously described. The constants were periodically redetennined " t h r o u g h o u t the stud;.- and are re­corded in Table X I . All equivalent conductances determined for the acid solutions wore calculated using the appropriate cell , .

yîviô-'i constants 'listed in-.Tab le XJI. ' • • ,'. .v^yb

Dens ity measurements. - The weights of all solid samples - • and water' were corrected to true mass in vacuo by the calculation) described above in the cell constant subsection. Thé -correction requires density values for the various compounds and these,, densities are listed in Table XIII. The' densities of the deuter-

_ated_acids_werp-.assimied-equal--to--t-hose--of—the i a'-protiimmOTalogues" ' 7 'in all cases. 'Hie val|le-fj fTisted without reference in 'fable XIIT v a l ^ ^ L :

were detenniricd in thel^^3bU|ig,unairjier

Cylindrical blocks-df, ffe| d'-material.were weighed m air, • ' '' ' * V . f '

and 'cither the dunensiohsy of,. t)>;pC'fused blocks were'measured with. V'C,-V ' [ '•'•'••"'•A '-' -. • -

microcalipers -or the- bïôc'kls. wér&' weighed in a solvent of known v -• - ' '- - g - V'

density-(water or eyelobysxahe;)). ,'The latter were completed rapidly so that dissolution of fife- acids in t'ne solvent was negligible. The"material was fused .by melting with slow cooling or by compres­sion with a- hydraulic press (ca. 5 x 10lb/in,) . Relevant com--parisôns indicated that the methods of fusion and volume measure­ment did not appreciable affect the results'.. -

V ŒIL CONSTANT DFATFTttIINAT IOXS

: / ŒLL CONSTANTS, c m ' 1 ; i 1 •

ŒLL I CELL II ŒLL I I I ŒLL IV - ŒLL Y

0 59294 j

0 50652 0 5085" 0 35791 0.567284

0 7 6 2 Q 2 _ 0 50652 0 50855 0 55790 0.36284

0 26296 ' 1 • 0 56655 • o 30860 ,. 0 55794 0.36287

0 t " 292 6 0 50652 0 30854 .; 0 3578.9. . 0.36285

0 29298 50635 0 -30853 • 0 35789 0.56286

0 ! 29292 •• 0 '30638 0 30865 ' 0. 35791 " 0.56291

0' 0 5065S 0: 50865 ' 0. 55792 0.36292

0 29295 0 30657 0 S 30864 0 55794 • Ck 56291

0 29295 0 50658 .0 30863 •• 0

A. 55801 0.36297

0 i 29295 0' 30658 0 50862, : 0. 35S00 - 0.36297

'Cont ' d l

cb:\'Œ\TRATIO.V RIÎX • " OF KCi soLi.rrjoK's

XTIMJ3LR (.MOLAR x 103 )

r ' • ' i.0005

: • 0 .98801 •

5 . ; 1 .0139

4 ' 1 .0026

5 " - 0 . 98855

6 . 1 .0062

' <'P . 1.Ù007

S 1 .0126

9 1 .0085

10 ___> 1 .0102

RUN.. •

XUMITE

11

12 •

- 15

.14 .

15

16

17

19 20 '

CONTTlrlNTrvViTON OF KCI sourrio.Ns

QMflLAR-x 103 j

0.88559

1.0041 '

0.9S564 . '

0.987 35- .

1.0038

0.96564

0.99509.

0.90105

1.0CT01

,.1.00815

*Kraus cells, see Figure.VII(b).

TABIT XI (Cont'd)

O'Ui CONSTANT DETERMINATION'S

•:LL CONSTANTS, cm"

(21: LL VI

0.0S575

O.C>S576 0.08379

0.0S376 " i 0.083""

' 0.28477'

0.2S4S5

v 0.28487 ^ .1 0.28480

i.284S)B

CELL VII CELL VIII.

0.198"6

0'. 19S76

0.1987 5

0.19871

0.19S"

0.2459.9

0.25002

0 ."24599

0.24394

0.2459S

CELL XI* CELL XII* CELL XIIP

CELL IX CELL

0.26096

0.26096 '

0.26094

0.2609S.

0.26099

Q.

0.265"

0.265

0.26538

0.26555

0.26555

:'N co - J

ACID

CcHs0a-I2CPOH

C TAB u-: XII

AVEIUCTD VALUES 01-" CELL CONSTATS EMPLOYED IN TEE

CAliTTLATION OF ACID-EQUILIBRIUM CONSTANTS'

CELL I.

0.&92Q2

±0.00002

CELL II

0. 50658'

+0.00002

CELL III. /

'•0..-30865

±0.00002

ŒLL "IV

0.5.5791

±0.00002

CcIlsOCDzCCOI

cia-i2ccai

CICD2ccoH

c6H5sai2coon^

CsHsSCDoCOOH

•0

0.29292

±0,00002

•0.29295-

±0.00002-

0.29292

±0.00.00%

0.29295-

* ±0.00002

0.29295

±0.00002

0.50658

±0.00002

'0.30638

+0.00002

0.50638.

±0.00002

0.50638

+0.00002

0.30638

±0.00002

0.50865

±0.0.0002

0.50865

+ 0-.00002

0.50865

±0.00002.

0.50S63

±0.00002 .

0.30863 c

TO. 00002

0.35791

±0.00002

0.35801

±0.00005

0.35791

±0.00002

0.55801

±0.00003

0.55801

±o;oooo>

ACID

c d i s S o^iTcaxi,

CdVCH 2 CœH

CeHsQO-IzCOOH

' J TABLE XII CCont 'dl ' i " X .

AVERAfiRD VALUES OP CELL CONSTANTS Fd-iï'LOYTSD IN'.THH j — — — =

CAL^rLATION1 OF ACID EQtHLIBPdLIM CONSTANTS

a-:LL i

0.292 95

±0.00002

0.0S576

+0- .00002 .

j CELL XI*

.0.2S482 '

+0.00004

a-PL i i

I 0.5005S i ! ±0.00002-

CELL VI ! CELL VII

0.10876 1 " J ±0.00001 )

! y CELL X I I I

0.28834

+0.00002

a-LL H I

0.30863

.±0.00002

CELL V I I I

0.24590

+0.00004

.CF.LL X I I I *

0.365S2

±0.00003-

CELL IV

0. 35501

±0.00905

CF.LL • IX

' 0. 2609,6

+0.0000 5

; CELL V

\ 0.56297

;± 0.00005

jcTELL X

3.26557

00005

-These' cells were used in conjunction v.'ith cells I to V for purposes of comparison.

90

TABLE XI IT

DENSITY VALUES EMPLOYED IN BUOYANCY CORRECTIONS

• QDMTOUND D E N S I T Y , ' c / m l Rl FI-Rll'CE

h'ater .0 .997075 / — : : (99) Potassium chloride • 1 . 08 • T H00) Phenyl acetic acid 1 .25- xTS9i Phenoxvacetic acid i - . . ' 1 .751

Chloroacetic acid Sf

1 .58 . (101) Pheny1thîoglyco11i c ac i d 1 . 57

Phenylsulfiirydacetic acid 1 .42 '

Phenyls,ul fonylacetic acid 1. .48

91

:. œNQ^WION-IKjUIVÀlENI' œNDUCTANŒ DATA A?m Tl-ERNPDYNANgC '

1:QUT LIB RI UM J5t9NSTANTTS

—-~~^Fhe~c-oneen^

acetic, phenoxyacetic, phenoxyacetic~Z,2-d? ,* ehlbroacetic, ,•' * ;

chloroacctic-2 ,2-dy, phenylthioglycollic , phenylthioglycol 1 ic-2 V ' ! -

2-d2, and phenyIsulfonylaçetic'adids in conductivity water at

25.000 r 0.002°C "(with, the exception of phcnylacetic acidsolu-

tions, noted above as' 25..051 i 0.002°C) are recorded in Tables''

XIV' to XXI (inclusive). . * -

Equivalent conductances recorded in these Tables are computed

t rom the relationship ' '• . ' i ,

.R-c . - ' , - . ' ' ' , •' *

winch is derived by combining and.rearranging Equations f60J and

[63J, • ' . ' .

.The abbreviated results of the- statistical treatments (de­

tailed above, pp.' 55 - -16)' employed-to'calculate thermodynamic

equilibrium construits from the concentration-equivalent conduc­

tance data of the acids are presented in Table's XXII to XXIX

(inclusive). The-latter also tabulate some equilibrium constant

oi these "a old s previously detemiined by .'other workers. The com-

putat ions( assocîated with these . results were accomplished'wjjch

the aid oT-an 1 .B.M. . 560/90 high speed digital computer and the

EortrafflV programs appropriate to the various methods of calcul­

ation are detailed in Appendix II. . y.r_ , '* •

s

R T'AI'.LE X I V -

DATA FOR PHILSA'LVCETIC A C I D

•Ç^N.a. NTOTO-TO. . . . . . . . . . . . - - ^y.EQmvALWï-LmmciwŒ----'

pp. 'CELL. VI CET; L VII CELL VI11 ci: L; P IX L X

61 . 087~ 55 > • . 1 5 ,

r . .33 ,r , 55 . 1 5 , !iô 53 . 1 5

47 . 3 2 8 2 .57 . 42 .45 37 . 4 3 5~ . 4 3 37 . 45

• 57 . 7 % È 41 .\59 41 .60 41 . 58 . 41 . 60 f 41 .'60 21. .99S1 53 .49 '55 .49 53 .48 - 53 .48 55 . 50

10. .71 72 73 .96 ' 73 .98 7:3 . 99 73 .98 " 7 5 . 99

0. .6954 77 .51 77, . 53 . 77. .35 77 .35 " 7 , .35

S. ,2337 83 .0.5 ' 85. .05 S'3, ,06 ''85. .06 83. , 06

6. , 775S .90 .52 90 . .34 9 0 . 36 90. 55 ' 90 . 36

6. 2448 -j 93 . 40 95. 51 9 3 . 55 95 . 52 93 . 53.

5. 5392 \ oq 0 ' ' 99. 94 9 9 . 96 no' 95 99. 96

3. \

9793 • |112 .80 112 . SS 112 . 88 112 . 82 112. 85

9584 1 27., .00 - 127 . 03 , 127 . 00 1 2 7 . 06 . 1 2 7 . 06

1. 9878 148, . 0 0 , 148 . 04 _ . 148. 09 148 . 05 / .1-4 S. 0 (5

' 0. 9947 188. ,15 188. ISS. 52 18.8. 29 V 188. 25

93

A SWMVRY OF CQNŒNTRATias'-EOllïV/\LB>}T CONDUCTANCE DATA FOR/F31 ENQXYACrTTIC ACID

-ewchAJTRAT'fmt „ ' ,.„„_'. .EQUrA^TO - -.

x 10" Q-OL/XIJ CELL I ŒLL TI CELL III CELL IV ' CELL V

60.4898 50.1886 40.289 S

'30.0870 '• 20. 0980 9.SI 70 9.0590 7.9804 • 7.0822 ~5.922S

5.0050 5.98S9 5.004 2 2.005S 1.0179

113. .02 113. 62 115 .65 113. 61 113 .65 122 . 56 122. 58 122 . 57 122. 57 ] ? ? .56 135 .62 13.5. 64 137 .64 153. 64 155 .64 J49. .37 149. 36 149 .54 149. 35' 159 . ~ r . _">D

1 72. . 70 fU2. 7 0 45A

172. . 70 172. 69' 172 .08 ' 217. .46 217.

7 0 45A 217. .45 21.7. 44 217 .45

TOO 6Q 7 "~> 22 1 .70 °2 2 •7? 222 .68 230'. .62 230. 62 • 250. ,62 230. 64 230 .62 258. 24 ?58 ?1 2.58. , 2 2 238. 23 238. .20 249. 50 249. 47 249. 48 249. 51 249. 46 2 59. S Or 259. 86 259. 8 259. 90 259, ,87" 275. 19 . 275. 1 7 275. 25 275. 25 273. .20 •289. 05 289. 04 2-89. 05 289. 07~ 289. 05 508. 71 508. r 50S. 71 50S. / s> 508. 69 33 3. 71 533. 66 33.3. 65 335.

>

7 7 -'535. 67.

. . Cont ' d >)D

94

COMCCNTR/YriON '

?iUilljXM^ ' C E L L X T C E L L X I 1 - , C E L L X I I I

rT6uT4-S?S.... - 1 Lv.dl-- - - 113:63 -113.64' s0.1886 122.57 ' 122.58- 122.58 40•"368 ;133.65 133.64 " 133.65

30.087^ 2 49.56 149.35 - 149,54

20.0980 . 172.71 . 172.70 172.70

0-S170 ^ ' 217.44 • 217.45 • ' 217.45

9.0590 222.70 222.69' 222 70

7.0804 250.65 250.62 250.62

7.0822- ' ' 258.21 258.22 238.21

5-9228 \^249.47 249.4S 249.47

5.0050 , 259.SS 259.88 . _ 259.86

3-9880 2775.22 -275.21 275.24

. -5-.-0042 ' • ~/l89704 ~28~9T0S" 28PJ)4~

""-•0058 - , 508.70 508.71 .508.71

1-0179. 555.67 355.60 533.66

J TABLE XVI

A SUMMARY OF CONŒMTRATION - EQUI VALENT CONDUCT ANCI:.

DATA FOR P!FErJ0XTACF:riC-2?2-d2"ACID:

CONCENTRAI" I ON ~ x 10" (MOEAL) CELE I

BQl 11 VALENT CONDUCTANCE

ŒLL I I I

'60.0800 5O.SS20 . 40.0041' 50.1594 20.0584 10.0255-9.0449 "A 93 58 6.9940 5.'8409

115.45 121 '.66. 123.42 148.60 172.05 215.36 222. 0(1 229.71 238.25 .24<L,.52_

5.0591 258.38 5.9671 272.61 3.0405 287.42

. 1.9357 •509.60

C E L L 11

115.46 121.68 133.45 148.58 172.07 215.57 2 ? o?

2 29.69 238.25 .249.50-258.38

-272'61 ^ - « i 287.43 309.63

CELL IV CELL Y

113.46 121.66 155.43 148.59 ' 172.09 . 215.57 222.00 229.74 238.26

-249 .-561 — 258.40 /\258.4 2

272.61

287.44 287.46 309.61 309.65

113.45 121.65 153.42 14S.58 172.05 215.37 222.06 229.74 238.26 /Fi. 53-

113.42 121.64 133.41 148.59 172.07 215.55 222.04 229.70 238.25 -249753" 258.41 272.60 287.45 509.64

96

TABLE XVTI

A SUW1ARY OF CONCI5NTRAT I ON - EQUI VALENT 'CQNDUCTANQ: • DATA FOR QILOROACETIC ACID « -

ftlNGiNTRATTON x 10" (MflLAL)

50.10'12 44.^25 59.9727 55.01 SI 29.8696 24.69S9 20.0424 15.1206

.10.1041 S. S561'

T 8v0417 6.9425 6.2159 5.0722

CELE 1 EQUIVALENT œNTOCTANCE '

CELL ' IT CELL III CELL IV CELL V

16T. 95 161. ,95 161, .94 161. .95 • 161. ,94 168. 58 . 168. ,59 168, .58, ••168. ,58 168, 58 175. 48 • 175. ,.47 , 175, .18 - • . 175. ,46 175. 47 1.85. 76 185. , / /- 1S5, 11 185. , 76' 185. ,75 195. 77 195. •79 195 .78 195. 76 195. .78 205. 97 205. .95 205 .96 . : 205. .95" 205, ,96 219. 44 219. ,45 219 .,45 . 219. ,46 219, 45 237. 95 . 257. .96 257 .95 237, .94 237, ,94' 265. 79 265, .81 265 .80 265. .81 , .263, ,81 271. 92 2 71; ."I 27l .94 271. .92 271 , ,92 2^7. 65 2 7 7 .65 277 .66 277', .66 277 .66 285. 97 285. .95 285 .98 285, .98 •-285 .98

292. 26. ' 7 0 2 , .•25 292 292. 29 7 ,26 505. 5S 505 .58 ' S 503 .58 305, .60 305 .58

m-

• . TABLE XVIII

DATA FOR ŒIX)ROAŒTIC-2,2~d?; ACID

COMŒNTliATlON x ID14 (MOLAL) . CELL I

EODI VALENT CON'DUCTANa••

cell u a-ill ni CELL IV ŒLL Y

49, .620 2 161 .95 161. .97 161. .97 44. .1062 16S .99 168. ,89 168. 90

40. .1143 174 .61 • 174. .61 174. 62 34. .555" 183 77 185. 77 ' 185. 75 29. .5648 195 .55 193. , 56' ' 193. 53 24. 7559 204 .95 204. .96 204. 94 20, .0241 .218 .66 218. .67 218. 68 14. 7642 258 .58 258. 5s' 258. 58 ,„9. ,8575 ' 264 ..56— —264. .-56--—-264--57-0. 9 7 ?-7 " 268 .59 . 268. 35- /: ' 268. 39 '.9 64-56, 280 i -> 2S0. .23 280 : 23

.6. 6853 288 .19 ' 288. 21 288. 20 h. •1 0599 • 294. . 01 " 294. 05 295. 99

4. 4945 1 510. . 04 310. 04- 510. 04

161.94 16S.88 174.60 185.7 5 .195.54 204.92 218.04 258.55

—264-54-2 68.38 280.25 288.20 294.00 i '310.06"

161.95 16S.89

' 174.58 185.74 195.5 5 204.94 218.65 258.55

—264756" 268.38

• 280.24 288.20 294 .'00 310.04

' TABLE XIX

98

A SIM-1ARY. OF CON CENTRAT I ON - ET) IJIVALEN T CONKJCTANŒ

DATA FOR PHEN^'LTIIIOGLYCDLLIC ACID

"

conci-;ntrj\TJON, a F, , F.QUIV.alitnt CONDÛCTANCE

x 10'' (M)LXL) CELIC l' - CELL IT • CELL III • Œ L L IV CELL V

50.0798 ' SI .74 781. .74 81. .74 81' .74 81. ,74

•45.5731 85 . 35. 8S5, f 85. . 33 .85 .3'2 85. , 55

40.2440 89 .86 89.

,41X

89. .86 89 .86. 89. S 6

54,964 2 9 5 .42 95, ,41X 95. ,42 9,5 .42 95', .42

50.IS80 . 101 .51 , 101. .51 101. . 51 101 .52 101 . . 51

25.0588 109 . 70 109. .70 109. ,70 109 .71 - 109. 70

19.8472 120 .55 120, . 55 • '• 120. ,55 • y 120 ; 56 120. . 55

15.1224 154 .20 154. .20 154. ,21 154 .21 154. . 20

9.9417 157 157. , 22 ' 157, .25 •157 .25 : 157. .23

9.0553'. y 162 . 79 162, .80 162V. 80 162 .81 - 162. ,80

8/0962 / . 169 ? 7 169, 7 7 , 169. ' , 169 .27 169,

6.8950 178 .91 17S, .89 178, .91 178 .90 178, .91

'^70LLlÀj~- —é 739 187 .59 187, .40 ) 1S7 . 37 187, . 37

5.027 5 19S . 50 Vs .47 198, .50' 198 .47 198, .48

TABLE XX

A SUMMARY OF CONCEANTMlNON-EOLmoUENT CONDUGTAXŒ

RATA FOR HIENYLTI1TOGLYCOLLIC-2 ,2-dr. "ACID

CONCENTRAT TON -. EQUR6VLJ5NT CONDUCTANCE

> K R (MOLALj CELL I CTLL' II . ' .CELL III CELL IV ÇIXU^

50AIS12- ; 81.01 SI.01 81.01 80.99 SI.00*

45.29 52 84.65 84.65 84.65 - 84.64 84 64 • • . . f

40.1200 89.20 ' S9.20 '89.21 - 89.19 "89.19 - • ' y"' • • ' •

55.0559 94.55 . 94.54 94.54 94.5 2 94.52

50.1815 100.6" 100.07 100.68 100.66 100.66

25.0760 108.74 108.75. 108.75 ' 108.74 " 108.73 2Q.0155 119.25' .119.25 119.25 119.22 119.22

15.0594 , 155.55 153.52 135.53. 155.55 153.52

10. 0253 155.70_. 155,.7J~C: 155.70 1-55-7-1——155r70~

'9.0059 161.84 Y 161.84 161.85 ' 161.85 161.84 8.0781 168.27 168.2" 16S.27 ,168.2" 168.27

7.0214 176.69 -.176.69 176.69 176.70 176.69

5.9933 186.55- 186.54' 1S6.54 ' 186.54 186.54.

5.0252 197.24 197."23 197.25 T97.22 - 197.25

v \ .: - ' 1 0 ( 1

TABLE XXI

A SUMMARY OF CONQ-Nril^TION-HjUIVAIJ-NT CONDUCTANCE

_ DAl-A-R^I^PhlFûVY-IîS HL-FeNY-M(3*T-I C—AeïD—"

OANTT.NTRYT- I OX I'QUI VAL1 .NT CON' 1K ) C F AX C1:

x . l C ' (MOLAL) CF.LL. I CELL 1 1 , CFLL 111 CFLL IV ' T i l Y

SO.1061 21".59 217.60 217.57 217.57.- 217.60

45.5505 -225.95 225.95 225.96 223.92 225.91

40.1804 251.60 , 231.62 231.64 • 251.61 2.31.63

35.0687 . 240.25 240.28 240.26 240.26 240.26.

50.2559 ' - 249.58 249.58 \ 249.57 249.55 249.55

25.0841 260.86 260.87 260.84 260.86 -260.86

20.0247 2 '274.11• 274,14 274.14, 274.15 274.15.

15.0929"' .290.13 290.12. 290.13 290.1! 290.15

10.0297 510.21 510.20 510.21 310.20 510.21 '

87795 514.84 514. SS 514.86 51 4.85 514.84

S.0957 519.32 519.51 519.52' 519.32 519.51

6.9700 525.1 1 525.10 ' 525.11 ' 525.1 1 525.11

5.9956' 550.81 550.81 ' 350.82 550.82 530.82

5.0571 536.40 536.59 556.40 " 336.39 356.40'

3

101

TABLE XXII

12QUI LI BRTir>1 CONSTANTS OI: PllliNi'lJVŒTIC ACID DERIVED FROM VARIOUS,

TITSVITuENTS OF EQUTVALI9XT CONDUCTANCE DATA OVER A

CONGiNTRAT ION RANC1:. OF 161. OP - 1.988) x lO - 4 MOIAL

'MI ill 101 ) /

ROBINSON-STOKES

S M E M / V V S K Y n

C R A S S rC A D

' I V E S

F1KASS

S I I F D L O V S K Y I

T'.QUILIDRIUM

CONSTANT, K t x 10;

4 .9S() ± 0.010

49128 t 0.010

5.790 + 0.018 (K ) .

4.'957, t 0.011

4.927 t 0.015

4.92b i 0.015

A Q ( R E E E I U T N C I : ;

579.6 (102) 579.0 (102)' 357.6.

' 379.1

'379. 9

380.1 .

SOME PREVIOUSLY. DEEERMINED VALUES

MET1IOP OF MI:ASURJ:An:AIT 150(11 LIBRIUM

(Mli'IHOP OF CALCULATION) CONSTANT, -K x -10:

CONIXICLVNCli

I ROBINSON-STOKES')

CONDUCTANCE CONDUCTANCE (IVES) EI1XTR0M0TIYE FORCE

40X23 + 0.015

4.887 .+ 0.056

4 .'90 (WLAR)

4.018 + 0.011

, (RBFT.RI.NCF.)

579.6 (44)

385.7 ' (85)

--- (105, 104)

(105)

TAB LP, XXIII

nqij] LIBRIUM CONSTANTS OF PI RF.NOXTACTTiy ACID DHRIVT-D PROM VARIOUS'

TRF.ATMl-NTS'OF FQUIVAIJiNT CCHNDUCTTANQ: DATA OVFR A CXANCFNTLCVRION RANGE OF (50.19 - 5.005) x 10"" MORAL

ROBINSON-STOKES

SIN-DLOVSKX' I I

CLASSICAL

IVFS FUOSS

SIIKDLOVSKY I

F.QUTLIBRILJM

CONSTANT, K ^2CJ22X

7.505 ± 0.0Ml 7.,283 ± 0.0144

8.195 t 0.0045 Ok' ")'

7.270 ± 0.0144

7.241 t 0.0108

7.255 t 0.0172

ÎLo

580.5*

580.5*

570. 0

580.7

581.2

381.5

SOMF PREVIOUSLY DETERMINED VALUES

EQUILIBRIUM

METHOD OF' MI'7'VSIIIY-;MI:XRR . CONSTANT, K X KV t_

CONDUCT ANCP;

I:U-:CRROMITN\'E: FORCE

F.LI-CRRONIN-IYT.' FORCE

".59 f MOLAR.)

0.7 5

6. 58

A 0 RI^N-IU-NAO

-- (19(0. (90)

-- (45)

*SheJlovsky IV A 0 value, sec Table XXXII below.

\

103

TABLE XXIV

EQUFLI RRIUM CON.ST.ANTS OF ElÉNOXYACTTIC - 2 ,2 - d ACID DERIVED FROM

VARTOUS1 TfyiBXTT-IEXrTS- OP. E.QIHVALENT CONDUCTANCE DATA' OVER" ,A

CONCiyrilATION RANGE OF (50.55 - 5.059) x 10'" WIAL

METHOD

I T>B INSON - STOKE S

SIIEDLOVSKY II

CLASSICAL

TVES

FUOSS '

SHEDLOYSKY I-

EQUILIBRIUM

CONSTANT, K t x 1Q;

7.205 ± 0.0180

7.195 + 0.O162

S. 129 + 0.0046 (K

7.219 ± 0.0152

7.185 + 0.0176

7.176 + 0.0180

380.,5-

,380.5-

570.1

580.2-

580.7

•580.9

AShedlbvsky IV A0- value for protium acid, see Table XX7XIF below.

104

TABLE XXV

EQUILIBRIUM CONSTANTS OF QILORQACLTIC ACID PERIOD FROM VARIOUS

CONCENTRATION RANfTE 01^^44'. 7 ~~ - ËToZ) ^"l^" '' MOLAL .

MED KID

ROBINSON-STOIQ-S

SIIEDLOVSKi' IT

CLASSICAL "

IVES

HJOSS

- f lOLOVSET 1

EQUILIBRIUM . . -

C T S J ^ ^ ' < ' A p .

1.399 + 0.0032 390.1* t

1.396 ± 0.0052 . 390.1*

1 . 5 7 2 ± 0.0022 (Kcj , •381.0;V

1.394 ± 0.0052 ; 390.3 •

'1.588 ± 0.0057 590.8

1.586 ± 0.0057 390.9

V750N1E PRIATOUSLY DETERMINED VALUES .

METHOD. OF- N1EASUITE3MENT

CONDUCTANCE

CONDUCTANCE

CONDUCT AN (7E

EQUILIBRIUM

CONSTANT, K t l x 10 3

1.596 (MOLAR)

1.596 (MOLAR)

1.559 (MOLAR)

Ap (REFERENCE)

389, 5 (107)'1

389.6 (108)

' 592.0 ' (42) -

*Shedlovsky IV A 0 value, see Table XXXII below

• .•• :•• "x • , • >'105

, •"' TABLE XXVI

EQUILIBRIUM CONSTANTS OF QiLOROACETIC - 2 ,2 - d 2 ACID DERIVED-FROM VARIOUS TITiATT'IFJTTS OF EQUIVALENT CONDDCTANCE DATA OVER A

CONCENTRATION-RANGE OF (44.11 - 7.646), x, ID ' IDEAL

ME1TIOR

ROBINSON-STOKES SHEDLOVSKY 1 1 '

CLASSICAL TVES FUOSS SHEDLOVSKY I

"Shedlovsky TV A0 value for protium acid, see Table XXXII below.

' EQUILIBRIUM CONSTANT, Kf x 103 ' /V

1.382 t 0;0003. , 390.1* 1.379''+ '0.0014 ' 390.1*

• .1.555 +.0.0052 (Kc) - 380.9

17375 + 0.0042 590.5 1.575 1 0.0052 590.7 1.571 1 0.0057 390.8

r 106

TABLE XXVIT

EQUILIBRIUM CONSTANTS OF PlIENYLiIlIOGLYCOLLIC ACID DERIYT.D FROM VARIOUS TREATM2NTS OF EQUIVALENT CX3NDUCTANCF. DATA OVER A • CONCENTRATION RANGE OF (50.08 - 5.027) x 10"'* MOLAL

ME'IHOD |

RDBINsm'-STOKES SHEDLOVSKY II CLASSICAL

, IVES- , FUOSS SUFDLOVSKA' I

EQUILIBRIUM' CONSTANT, KA. x 10''

2.805 l 0.0040 2.799 f 0.0041 5.105,-.+ 0.0050 (Kr) 2.799 i O.O040 2.778 + 0.0048 2.775 -t (E0049

SOME PREVIOUSLY DETERMINED VALUES

2222

581.2-3S1.2* 367.0 5S1.3

75ÏÏ27-4 382. 5

EQUILIBRIUM -MET! [QD-QF'TEASURBPTiNr

CONDUCTANCE ELPa'ROMOTl\1 ! POUCE

CONSTANT, Kt x 10'

2.76 t 0.04 2.70

An (REFERENCE)

381.1 (46) (4 5)

*Shed]ovsky IV A R , value, see Table 'XXXTI below

T A R E E XX\ R I I [

* S h e d l o v s k y I V A r i v a l u e f o r p r o t i u i n a c i d ^ s e c ' f a b l e X X X I 1 b e l o w

, 752 + 0.0025 581 , y ,749 + 0.0036 581 . 7>, ,114 + 0.0059 ( ' ;367. 8 .•7 54 O.OaS^ 581. . 0

0 ,700 0. 0067' • 383. 4 y ,705 + ,0.0008 3S5. . 5

\

I ; Q D J L I B R I U M C O N S T A N T S O F piriwi:ni[OGLYmLLic-3,2-l\? A C I D ' nr.Riv

FROM V A R I O U S TRB .Al 'MBNTS O I : E Q U I V A L E N T CONPUC1ANCE DATA O V E R A

CONCITUlcVrION RANCH O F I S O . OR - S,I12^J^\-JIL^.lÛJ^t •

H Q U I L I R R I I I M

METHOD , C O N S T A N T , E> X !()'' ' A '

R O P . I N S O N - S T O K ' F S

SI IHDLOVSEA' I I

C L A S S 1 CAE

I V F S

F U O S S

S1IRDLOVSKY 1

. 08

TABU- XXIX

EQUILIBRIUM CONSTANTS OF ITIBMi'LSl1LEONY1 ACTTJC ACID DERIVED FROM VAUOUS TRl-iAITOLNTS OF EQUIVALENT CONDUCTANCE DATA Wl:.R

— -y\-(-ONa7r-[TMTdo\'-FAaNcr .x ..TO":'' ipiAi, -

. FQU1LIBR1UM FTjjTTJC ' CONSTANT, Kt x .103 •' A(1

ROBINSON'-STOKliS SHIiDLOVSKT. 1 I CLASSICAL ' 1\T,S \ F1X2SS S1TDLOVSEY I

3.670 + 0.015

3.663 ±'0.012 •1.066 + 0.001T CKC:

3.661 ± 0.015 3 . 64 3 ± 0 . 0 15 3.642 ± 0.015-

579.7* 379.7* 57-3. 5 579. S 380 Al 580. 2

SOME ['REHOUSEY DFHT.RMINED VALUES

-EOUIL1BR1UM-MEDiOD OF MlASlTvlXlEjST CONSTANT, Kt x 1.03 A,, (REFERENCE)

CONDUCTANCE EI.ECrilOMOT I VF, FORCE

5 765 ± (L04

5.0 7>

379.6 (46)

-:- (45)

•SbedlovsEv IV A,-, value, see Table XXXII below.

109

5-5. ISOTOPE liFPECTS-

Secondary isotope effects of the second kind calculated via ecu V the Shedlovsky 111 Method (described above, pp. 53 - 56.) for

-the-i-sot-opic—aeid^ and PhS, have been 'tabulated in Appendix III. A summary of these isotope effects is presented in Table XXX.

tIsotope effects derived from the appropriate comparisons of thermodynamic equilibrium constants [see 'tables XXII to XIX] arc listed with those calculated by the Shedlovsky III -Method in Table XXXI. ' '

ÎSOIOPF, I-I-FI-CTS PF.RTVFn FROM SIII-DIPVSKT 111 I'RFA'IMFNT OF Q1NŒNTRATI ON - F(JljJ WUJJT^ •

•DATA •

ŒLL NUMBFR , jyAOTOPB FT'Fl'AT, in f (P) /mt (II)

1 1.0104 ± 0.000O

2 1.0099- ±.,0.0008 5 1.0104 + 0.OO09 4 . * 1..0108 + 0.0009 5 1.0109 ± 0.0009

G i l o r o a c e t i c

Phenylthioylvcol1ic

1 .0114 t 0.9008 1.0116 ± 0.0008 1.0116 t 0.0008

1.0114-+ 0.O008 TAPIR) t 0.0008

1.020 7 t 0.OO06 1.0209 ± 0.0006 1.0205 t 0.0006 1 .0211 t 0.000-7 1.0211 t 0.0006

Ill

TABLli XXXI •

A COMPARISON OF ISOTOPE EFFECTS FOR THREE .ISOTOPIC ACID PAIRS

MLITIOD OF- - -V - - - - ISOTOPE EFFECTS "FOR •R'iSH OOOH/RCDaCOOH ;

CALCULATION-' R PhO ., "R - CI R ± PES

Rob ins on-S t okes 1 012 + 0. 005 1 012 + 0. 002. i .02 0 * 0:001 Shedlovsky II 1 012 + 0'. 002 ' 1 012' + •0. 002 i 020 +'o.ooi Ives 1 DOS ± 0. 002 • 1 014 t 0. 005 i 024 + 0.002 Fuoss 1 008 0-. 005 • 1-Oil ± 0. 004 ' i 027 + 0.005 shedlovsky I 1 008 + O. 002 1 011 t 0. 004 i 026 ± 0.003 Classical 1 011. ± 0. 001 1 012 t .0. 001 r 021 t 0.001

Shedlovsky j-II .->' 1 011 + 0. 001 1 012 + 0. 001 i 021 ± 0.001

112

5-42 LIMITING MOUIVALENT DUCD\NCB (A n ) VALUES '

Values of Abused in the/Direct,'Methods, of thermodynamic

"—equi-l-iEî-iimi-Gonst-(int— GaTGuTatTon-were-obt-airied—f-rom al-t—Method—•

values (converted to the ,molal scale) determined by other'workers

and from the Shedlovsky IV treatment cjf the concentration - c'quiva -

lent, conductance data of the acids. The abbreviated results of

the Shedlovsky IV treatment of the data are presented in Appendix

IV, and the A 0 values'of the acids determined hy this method are summarized in ./Fab le XXX11. . .

f

TABLE -XXXII

VALUES DERIVED FROM SIEDL0V5KY IV TREATMENT OF CONCENTRATION - EQUIVALENT CONTJUCTANCE DATA

ACID

Phenoxyacetic

Phenoxy acetic- 2,2 -d2

Qiloroacetic

•iloroacetic-2,2-dz

Phenylthioglycollic

Phenylthioglycollic-2,2-d2

Phenvlsulfonvlacetic

\'ALUE THAT YIELDS MINIMUM ERROR IN SHEDLOVSKY K

CELL I CELL II CELL III CELL IV' CELL V

3S0. S

I 380.0

3 9 0 . a j

3 9 0 . 6 j

3 8 1 . 3 ) i 3 8 1 . 7

!

5 7 9 . 7

!

5S0 5 3S0 5 3S0 6 580 4 380. 5

379' 9 380 o • 380 1 • 380 1 [ 380:0

390 1 590 1 390 1 590 1 390.1

390 6 590 - 390 5 390 V : 390.6

3S1 1 581 3 381 1 381 9 "381.2

581 6 581 5 • ' 381 S 3S1, S ; 581 .'7

379 6 379. / 579 7- 579 l. " 379.7

AVERAGE A,-,

4-1.. llHrT DDYNAMIC EQUI LIRRJUM CONSTANTS •

-,4-la. A. COMPARISON Willi 11 IE.-LITERATURE

'The determination of the themodynamic equilibrium constant

of phenylaectic. acid in the present study was' attempted for com­

parison with values previously reported. The demonstrated re­

producibility ôf the Kt.for this acid, when compared with values

previously' determined, assures some measure of reliability in the

• technique.

Values of the K t of phenylacetic acid calculated via the

various methods described above arc reported in Table XXII, and,

with the exception of the Classical calculation, the values de­

termined by all methods agree to within 0.3",. More significantly,

.these values are in excellent agreement with those recentlv de-

• termined by both conductance and electromotive force methods ('44,

"3TlXf5TT04TT05) .

The K t values of phenylacetic acid calculated bv the Direct.

Methods, namely the Robinson-Stokes and Shcdlovskv II Methods,

were evaluated using a corrected value of A 0 . The correction of

tins parameter was necessitated by an oversight in the bath temp­

erature adjustment (the temperature was actually 25.0S1°C instead

of 2S.000°C), and was accomplished using data provided by Laugh-

ton, and Demayo (104) . These authors have proposed the linear

variance of the limiting equivalent conductance of phenylacetic

•' . ••US

acid over the temperature range-of 20°C to 40°C'according to the

-equation

165] - - Ac,- =-' ;-1122c08 + -459614 T : " " ' " "

The increase of 4.9614 -A,, units per °K yields a A. value at

25.051°C some 0.25 equivalent; conductance units (cm' i~ 1 mole"1)

higher than the A n value (quoted for 25.000°(i (102). '

In their investigation of the temperature dependence of the

thermodynamic equilibrium constant of phenylâcetic acid, baughton

and Demaxo qT04) obtained only a 5.92 decrease in K over a temp­

erature range of 20^6 to 40°C. On this basis, temperature cor­

rection of tnc K values calculated at 25.051°C in the present t study was considered unnecessary, as the correction represents

about 0.012 of'the quoted K value.

The t hcnnochnamic equilibrium constants of the other acids investigated (see Tables XXIII to XXIX) indicate that while cer­

tain oi. the evaluative.methods, appear more precise"than others,

the discrepancies between the K values generated for any one

acid by the diiferent evaluative techniques are diminutive. IVith

the exception of chloroacetic acid, the K values of theqirotio

acids are m excellent agreement with prcvious.lv reported values

determined by the "conductance method."

In the case of chloroacetic acid, although the values of the

thermodynamic equilibrium constant reported by Shedlovsky and

' 1 1 6

co-workers (107, 110) and Saxtoh^and Langer (108) are coincident » • • ' ' . . .

with values determined here, there' is considerable discrepancy

between the latter..arid_tha^uch^ow&r—^

constant reported'by' Ives and Pryor (42).. In their highly prc-

'Nfe, cise investigation of monohalogenoacetic acids, Ives and Prvor

suggest that "erroneous values of A 0 obtained via tlie Salt Method,

(see above, p. 47) may account for the discrepancies in reported

* themiodynamic equilibrium constant Oalues of chloroacetic acid.

These authors ascribe the error, in- An measurement to hvdrolytic

decomposition',of aqueous sodium chloroacetate wliich gives rise to

inconsistent conductance measurements of the unstable salt solu­

tions. Instability of the salt solutions has not been previously

reported however [c.f. ' (107,J10) ' and (108)], even in highly

alkaline media under moderate conditions (111), nor did the 1

chloroacetic acid solutions in the prcyseivt ud\y^ow__ç7xid.ence

of instability.

To accommodate the highly precise, yet lower, thermodynamic

equilibrium constant reported bv Ives and\Prvor lor chloroacetic.

acid, speculation must lead to the possibility of a homogeneous-

impurity present in their acid sample which would lower tire K t

value. The two obvious possibilities are bromoacetic acid, an

impurity in commercial samples of chloroacetic acid and one which

is removed only with great difficulty (111), and water. The

notoriously hygroscopic nature of chloroacetic acid necessitated

its weighing in a dry atmosphere in the present study, but this

was not the procedure followed in the Ives-Prvor'.study (112). -

The therrnodynanu'c equilibjrji^ ons.tant_of— phenylsuTf-bnyl-'y

acetic acid has been measured by Crockford and Douglas (46),

who employed a conductance technique,, and by Pasto and Kent (4 5) ,

who used an electromotive force method. Although not in agree-

ment as to the absolute value of the ionization constant'of s

phenyl suif iny lace tic acid, both groups of workers note that the •-

thermodynamic equilibrium constant of the acid is unusuallv

t large in comparison with-the. values of phenylthioglycollic.and

phenylsulfonylacetic acids. Indeed, Pasto and co-workers (45, '•

115) go to some lengths to explain the anomalous oehaviour of

these three acids in aqueous and non-aqueous media. 0-

The thermodynamic equilibrium constants of the protio.and

deutero phenylsulfinylacetic acids arc not report<^ irild^^

as aqueous phenylsulfinylacetic acid proved unstable to conduc­

trice measurement. The change of resistance of the acid solution

with time indicated a process of uniform rate was occurring,

probably a decomposition of the type originally proposed by

Pummerer (114) and recently examined by Walker and Leib (115).

This process was accompanied by the deposition of a sparingly '

soluble material on the cell electrodes, which was removed only

after repeated washing.

Aqueous phenylsulfonylacetic acid evidenced no instability

to conductance measurement, but a uniform decrease in resistance

1 1 s

v i t h timcwas. observed for solutions of the -deuterium acid ana-' ..logue. As the aqueous prptio acid appeared stable, this resis­tance change is attributed 'to the re-exchaftje of hydrogen for deuterium at the methylene' position of the aqueous deutero acid.

119

4-lb. UNCERTAIN"! i' IN THF, PRESENT RESULTS

A small residual concentration dependence oT equilibrium constant values derived From conductance measurements has recent-ly been noted ( " 8 , 44, 7S, 116, 1170 A., TJiis-dependen(;e-c;an-lie -Aascribcd to errors associated with Trequency dependence of-mea-;C-sured resistance, significant specific,''conductance of solvent, hydrogen bonding' differences between the isotopic atoms . and-the ' solvent, incomplete isotopic substitution in the dcutero' acids, and the use of inaccurate limiting equivalent conductance values. Each of these sources of error will be discussed ,in turn.

The frequency dependence of electrolyte solutions continues to be a complex problem of current research interest [c.f. (118)'] Tire highlv precise conductance measurements on substituted acetic acid solutions'bv Ives et al. (42, 112, ll°y. 120) using four-lead double cells enabled these workers' to confirm the approximate linearity of resistance with reciprocal frequency Although" Jdie_ function oi resistance with frequency appears to depend on the type of electrodes employed (121aj, Prvor (112) notes- that the

quency dependence of the resistances associated with solutions of monohalogc-noacetic acids is insignificant," not -exceeding 9.OK of the apparent resistance. This observation was confirmed by Ives and Moseley in a later communication (122) in which-'these .authors waive tire double' cell advantage of small residual fre­quency dependence in favour'of the statistical advantage of two •

120

separate cells. The effect of•frequency dependence on apparent resistance in the two separate cells-was reported as "almost inconsiderable". ' In the present investifiut ion, the frcq uej y ilepen dene e-o f the resistance measurements obtained on the impedance comparator (G.R.I..C.) appeared-not to exceed 0.022 of the resistance values. However, resistance measurements on the Tinsley bridge showed some frequency- dependence, but subsequent extrapolation of re­sistance as a function of frequency yielded resistance values within O.OIu. of those obtained on the impedance, comparator.

The -correction of specific conductance values of acid'solu- ' tions has been advocated by Laughton and Demayo in a recent extensive study of errors associated with conductance measure­ment (104). This correction requires the subtraction of the specific conductance of the conductivity .water from that of the aqueous acid prior to'the calculation' of equivalent conductance __ Apart Taooni conductivity due to it? own'dissociation, the specific conductance of conductivity water is usually attributed to the • presence of dissociated carbonic acid (121b) i While it cannot be considered negligible in the case of potassium chloride solu­tions Ic.f. Equation [61]}, this dissociation must be altered in solutions- of other acids. The solvent correction factor then :

r

becomes- extremely difficult to estimate and its application is of questionable necessity.

121

As current theories of hydrocarbon solubility- in water sug­gest that specific interactions between solute and solvent are weakj the effect of hydrogen bonding differences between the methylene II and I) atoms with water is not considered to be a "parameter of sufficient magnitude"to influence the hydrodynamic properties of the dissolved acids.

Errors associated with the effect of incomplete isotopic substitution on the t hemodynamic equilibrium constants of the deuterium acid analogues have been examined by Scott and Benson ( 7 9 , ll7). Incomplete deuteraticn of the methylene group results from either partial deuteration during preparation or re-exchange (protium for deuterium) during measurement, and it leads to a mixture of RGhOACII, RCHDœOII and RCD :COT1. Scott and Benson

.assume K't(l[9l equal to the geometric mean of K-tyO'O 'ant^ t^D) in their calculations and treat the problem classically, i.e., thev neglect intcrionie effects on both the activities and mobilities' of the ions involved in the equilibria, 'fliese authors conclude that the validity of the Kt(D) determination will not be serious­ly endangered if the deuterium content at the methylene position is not less than 957.

The-errors associated witli 1 uniting equivalent conductances produced by the•simultaneous generation of A n and K t via the In­direct Methods has attracted considerable comment ( 3 S , 8 2 , 104 ,

1 2 5 ) . Belcher (82) has compared linn ting equivalent conductance values obtained from the Salt Method wdth those derived from the

iterative techniques • (see Table XXXIII) . Me concludes that the iterative-extrapolation techniques of the Indirect Methods are onlv reliable if the electrolyte has a dissociation constant -greateiwthan-1—x—10—.—I-f—the-therrrodynamic- equ-id-ibr-]iDn-eqnst,ant of the electrolyte is less than 1 x 10"5, then the AG value, and hence the Kt- value, will be in serious error. Belcher maintains that even if the theoretical expressions for data treatment are .adequate over the complete concentration range investigated, an accurate value of A 0 will not be determined unless the'random errors are small and the number of empirical data points is large.

Belcher's contention is supported by Kilpatrick (123) in her investigation of errors arising from the generation of A Q via the Ives Method. The results of extensive data treatment by both Barnes (44) and Demayo (104) provide further confirmation of Bel-cher's observation. Indeed, in.the present work the variation

with changes in A0 on either side of the best value (see Table

XXXIV) However, the data of Ives eat aT: (42, 119, 122 , 124 , 125,

126), processed by the Ives Method, appear to give excellent results", but this may be partly, a consequence of the relative

\ strengths ot these acids. As Belcher (82) notes, the data^de-

rived from relatively strong acids require only short extrapol-

ation in the, generation of A0. The original intention of Tves

TABLE XXXIII

-. . — : - -F R O M A C I D A N D S . A L T ' Fj 'yQfi A C I D . A L O N E

A C I D a- ' ' : A , Kr x 1 0 s

it.

K t x 1 0 5 P Œ F E R É N i

>

C a r b o n i c 5 9 4 . . 3 0 . 0 4 3 1 4 2 4 ' 0 . 0 5 6 5 ( 1 2 S )

A c e t i c 5 9 0 . . 7 1 1 . 7 5 3 3 9 5 . , 3 1 . 7 0 5 ( 7 5 )

P r o p ! o n i c 5 8 5 . . 4 7 1 . 3 4 5 . ' 5 8 6 , , 5 4 1 . 5 3 7 ( 8 2 )

C t r l o r o a c c t i c 3 8 0 . 5 2 1 3 9 . 6 5 8 9 . , 5 1 3 9 . 6 ( 1 0 7 )

n - B u t y r i c 5 8 2 . 4 0 1 . 5 0 8 • 5 8 6 . , 0 5 • 1 . 4 7 5 ( 8 2 )

B c n c o i c 5 8 2 . to

6 3 1 . 2 • 5 8 2 . . 1 6 5 1 . 2 • ( 1 2 9 ) -

o - C t i 1 o r o l i e n c . O I C 5 8 0 . . 0 7 . 1 1 9 . 7 5 8 0 , , 0 1 1 9 . 7 ( 1 3 0 )

A CatPABISON O F A n A N D V A L 1 T : S J 2 £ ^ A

ACIDS-TAPAILÀTnn B Y B E L C H E R ( 8 2 )

TABLE. XXXIV

- - - -SOLUTIONS OF CFiLOROACETIC ACID IN CTELL NUMBER I

CONCENTRATION' . A 0 =588.5, A0 = 590.1, - A n = 590.8,

.x 10" fMOLAL) fKt and 3) x In5 (Kt and 5) x 10s (Kr and 6) x 10s

44.7S2 141. 4 + 0. ,5252 159 .6 + 0. 1994- 158, ,9 + 0, .0753 59.977 141. , 5 + 0. ,4175 139 . 7 + 0. 1210 139. .0 0. ,0073 55.018 141. , 9 + 0, ,1255 140 .0 - 0. 1582 159. - 0. ,2385 29.870 - 142. ,1 0. ,2179 140 . 1 - 0. 1955 159. ,4 - 0. .27 56 24.699 142. , 3 - 0. .1022 140 _ 2 - 0 . 2 556 159. .4 - 0, . 5112 20.042 142. i - 0. ,0553 ^ 140 .0 0. 10 51 159, - 0, .1516 15.12L 142. .5 - 0. ,2850 140 - 0. 2172 139. , 5 - 0, .1920 10.104 142. - 0. .3897 159 _ q 0. 0675 153, + 0., .0555 ^878361 ~T4"2" , 3 Tc T058"" 159 .4 + 0. 5209 138. . o 0. .482" 8.0417 142. , 3 0 , ,1173 ' 1.39 . 3 + 0 . 5897 13S. 9 + 0. , 5826

AVERAGE

(Kt ± 6) x 10 5 142.1 ±0.400" 159.9 ± 0.5177 139.0 * 0.4152

FOR CELLS I-V

A COMPARISON OF Kt AND DEVIATION (6) VALUES, DETERMINED BY

DIE ROBINSON-STOKES METHOD EMPLOYING -VARIOUS A 0 VALIJES, FOR •'

125

(42, 72)'in the development and use of-the iterative-exyrapola- ;

tion technique was to safeguard against salt decomposition in

aqueous,,media. A similar situation is encountered in tire present

••-work,- in" as "much as the salts of the" various deutero acids may

be subject to rapid re-exchange in aqueous media (lid) . Hence,

although desirables direct measurements of A 0 by the Salt Method

have not been attempted in the present study.

The Shedlovsky TV treatment of'concentration-equivalent

conductance data (see Appendix TV) developed dyyScott et al_. (38,

79, 117) provides a useful alternative to the iterative-extrapol­

ation methods of Fuoss (69), Shedlovsky (70, 109) and Ives (72)

in the determination•of A 0 . This method does not rely on an

extrapolation but. rather finds its basis, in a linear least squares

interpolationi(sec above, p. 48). Some A 0 values produced by

this method are compared with those evaluated by the Salt Method ; . •

TiJûlthé"iterative methods in Table XXTvV. In all cases the A 0

values calculated by the Shedlovsky IV Method are closer to the

A 0 values calculated from salt data than those of an iterative-

extrapolation technique.

Tire apparent concentration dependence of the thermodynamic

equilibrium constants is undoubtedly influenced by, parameters

other than those discussed above [c.f. (127)]. Whether, for in­

stance, the theoretical model and the assumptions inherent in the

methods of calculation (e.g. the approximations, of a definite ion

size and the activity of undissociated solute) are.valid at the

• T A B L E X X X V

A COMPARISON OF A 0 VALUES DETERMINED BY TUE SflEDLOVSkT I

R' IN RObCOOI-l SIIEDLOVSKT I SHEDLOVSKY S A L T r TXT1 iOD ACIJ) I T É R A I T Y Ï M E T H O D • IV MElTiOD (INFERENCE)

H 391.9 591. .4 5 8 9.,6 (7 5)

Cf)lls 386.4 581. , 7 579.6 (102) 4-MeO-C5IE, • 380.2 577. .0 . 577.5 (81) 4-NO2-CMR 378.9 578. .5 376.6 (80)

Cl ' 390.9 <v 390. I 589.5 (107)

C 6H 5S 382.5 • 381. ? 581.1 (46) c ciBsn :, 580. 2 379. -7 579". 6 (46)

V

*The unreferenced values For the first four acids listed are

taken from (44) , and all others are from this study.

I T E R A T I V E iirmoD, T H E S I I H D L O V S K Y ToiiiTijQr^

A 0 ( M O L A L ) V A L U E S *

127

extremities of the concentration range is questionable. Since,

howiever,'this presentation is essentially empirical in nature,

m thA interests of brevity the discussion of theoretical para-metcrs- and their uncertainty; Is ''left'to', others ' [cf." (47, 48 , 51, 104/].

128

4-2. ISOTOPE EFFECTS

'The isotope effects exhibited by the three isotopic acid —r!'<;<"\<y-v/:^crCTr~V, C ïTT 'bi , and PhS, are compared in 122' A< XX2XI. These effects are larger than those measured by Scott and Barnes (38, 44) for they substituted phenylacetic acid pairs (R = C6lifi, 4-MeO-C6H„ and 4-N02-CGIP() but are less than those reported by Streitweiser and Klein (52) and Bates et (401 for the acetic acid pair, ai3cœH/CT)3CXX)Ki..

Hie isotopic ratios reported here are close'to the K(H)/

K(DJ value of 1.02 predicted by the inductive treatment described above, but do not correspond to the inverse isotope effects pre­dicted by Equation [12] for the correlation shown in Figure IV (see Figure TX). The influence of structural variation and the corresponding change in inductive effect on the isotopic ratios

.

—indicates-that—t-he-simple-induct adequate model for the description of isotope effects. This is clearly evident since tire model requires, to a first approximation, iso­tope effects to be independent of xthe nature of the substituent, i.e. constant with structural change, but the isotope effects reported here and elsewhere (58, 44) are in fact randomly influ­enced by structural changes. '• •

Although in excellent internal agreement, the isotope effects computed using .thermodynamic equilibrium constants derived from the Direct and Indirect Methods show greater

129

FIGURE IX A PLOT OF £ lofim K(H)/KÇD) - v s . pKÇH) FOR THE ISOTOPICALLV

SUBSTITITTED ACTTIC AÇID PAIRS RCHzOXWRCDzCOCH , . . . . ._ . Il i "

The K(H) and K(D) values for R = CHs are taken from ( 4 0 ) ,

the values for R = C 6 H 5 f 4-MeOC6Hi., 4 - N 0 2 C 6 H u are taken from ( 4 4 ) , and the values for R = C 6 H 5 0 , C 6 H 5 S , C I are taken from this work. The correlation shown in the Figure represents the linear free energy relationship given by Equation [ 1 2 ] .

to

5 OO

4 0 0

^ 3 0 0 O

£ 2 0 0

o

o I 0 0 -

- f c

0 0 0

-100

R = CgHgS

R = CI O • R = C 6 H 5 0

R=;4-N0 2 C 6 H 4

J 1- . • L-i

R = CH,

R = C 6 H 5

• R = 4 - M e O C e H 4

2 50 3 00 3 50 4 00 4-50 5 00 pK(H)

150

uncertainty than those calculated hy isotopic slope comparison

(see Table.XXXI). The larger uncertainty associated with iso-

tope_eJ5£ec

consequence of the fact that the'Direct and Indirect methods \

rely heavily on the accuracy of A0.'

An' examination of Appendix III reveals that a change of 1-

equivalent conductance unit in A 0 will produce a change in slope

which does not exceed 1 1 , but a similar examination of Appendix-

VI indicates hat for the,same change in A 0 the corresponding

change in Kt is to the order of 10°. The uncertainty of isotope

effects derived from tlie appropriate Kt- comparisons clearly must

be greater than the uncertainty associated with those obtained

from isetopic slope comparisons.

'Die uncertainty of thet,isotope effects derived from the

Classical isotopic slope_s^ppjea.rs„to3e_coinparablc-in-si-ze-to—•—

the uncertainty,associated with calculation by the Shedlev/sky

•111 Method, and less than the uncertainty attached to isotVxpe • \

effects obtained via the other methods. The"1 reason for this is

not easilv di seemed in view of the fact that ion activity and

mobility effects are ignored in the correlation of the "Classi- '

cal"'variables 1/A and A-c. However, the differences between

the contributions of these small, but significant,' effects to

their respective isotopic slopes-must be dimdni/tive,,since these

differences only reflect the perturbation of isotopic substitu­

tion on ion activity and mobility. - Although the influence of

131

these isotopic differences on the slopes may not" be negligible,

the .cancelling effect which occurs when the isotopic slopes are

jc.orap ar e d_by~rat-io-p rob a b Ty-a c c o unt s^orthc3ir~disappearance. -

A similar aspect of isotope effect calculation is presented

•when tire same value of A 0 is utilized to process the concentra­

tion-équivalent conductance data of-both protio and deutero

acids by the Direct Methods, i.e. A0(H) and A0(D) are assumed

equal. This value of A 0 need only be in the region of the true

A 0 to yield an isotope effect equal,,\ilbeit less certain,A.to

tliat obtained when an accurate value/yf A 0 is, employed. Some

justification of this empiriA?^^ is offered in the

following 'section. ( ^

132

4-3. THE F7QUAL1TY OF An (H) AND An(D) " ,y - yyyÂ.. • • '•••''"•A '• y

The calculation of isotope effects by comparison of ther­modynamic equilibrium constants, Kt(M)/Kt(D), and isotopic -slopes, mt(D)/mt.0d.) , relies heavily on the assumption that the limiting equivalent conductances.'of the protio acid and its isotopically substituted analogue are hot significantly differ­ent, that is <

[66] Ari(D)/A0(H) 1 .

By the subtraction of AND 4) Prom- Equat ion -[66], the approxima­tion may be reduced to a/consideration of the isotopically sub­stituted anions, l'iven bv

" 1 [67]- An'fPVAn" ('H) - 1

This approximation is not without precedent, having been implicitly assumed bv Streitwciscr and Klein (32) an their co?isideration of the acetic acid isotopic pair. Robertson and' co-workers.(36, 43) have also presumably .applied this approxi­mation in their investigation of some psotopically substituted tetraalkylammonium ion pairs,' as have Bell and Miller (131) in their studv of the formic acid isotopic analogues. The isotope

x" ratios reported by Strertveiser and by.Bell are in excellent acreeme nt with those determined by other empirical techniques

1

135-

(40, 1 5 2 ) . If Aq is a function of isotopie substitution, deu­terium for-hydrogen, then the I uniting equivalent conductances of the ClIjCœiI/CDaCCXDII and dlCOOII/IXDOIHTcIa-pairs must be more significantly affected than the isotopically substituted acetic acids examined in the present work. - ^ . '

Nevertheless, hy virtue of the diminutive nature of the isotope effects reported here, the assumption implied bv liqua­tion 107] necessitates closer scrutiny to insure the integrity of the isotope ratios. In the methods utilizing isotopic slope, comparison, the isotope effect was giverrf-above as the ratio of liquations [51] and [52] which leads to

Kt(il) . ' ' mt(D)A/ÎD) [ 6 8 | .= •

Kt(D) mT(H)A02(II)

where the parameters have their usual significance. Clearly, the uncertainty in the isotope effect is the product of the uncertainties in the ratio of isotopic slopes and the ratio of [A0(D) /A0(ll) Y . The val idity of the real but small isotope effects reported here requires that the latter ratio be much closer to unity than the ratio, of the isotopic slope<sA -

Scott cyt a_l. ( 5 8 , 78, 133) have critically examined the approximation in Equation [ 6 7 ] by employing an approach of'wider scope. They note that the effect'of isotopic substitution on . the limiting equivalent conductance of ions may be considered

part of the more extorsive problem of theVariation of ay with structural change. ^

.XI though th'e effect of structural variation on the limit-' ine equivalent conductance of simple spherical ..cations, and anions appears complex (47),'the problem has been broached by

considering loirradius as the significant structural parameter (154, 135;). This approach has been adopted by the sophisticated Fuo'ss-rJoycDZwancjg theory- ('156] in the investigation of the -:* hyJrod>Tiamic properties, of spherical ions. This tbeorv involves the assessment of ion-dipole interactions arising fi mythe

• fractional -forces created by the viscous-and dielectric proper­ties of the medium.

however, tlio molecular anions of the substituted acetic acids are not spherical- in shape and hence cannot .be'adequately delined by an ion radius. The ion-dipole internetIons'must consequently be i-eplaccd hy dipole-dipole interactions between ' the molecular anions and solvent. Differences in limiting . • equivalent conductance for the isotopicully substitut copiions fc'ould arise from differences in size between the H and D anal-' ogues and differences in dipole moments between O H and C-D bonds.

Scott' (135) lias correlated the limiting equivalent conduc­tances of some carboxylic anions of the type shown in Figure X. with a parameter (Tm) employed to defin^ anion size (see Table

> 4.. ' " '

)

13S

A DIAGRAM OF THE TYPE OF CARBOXYLIC • . - j -

ACID ANION CONSIDEP£D IN EQUATION [691

136

XXXVI). The T m parameter is the mean of the bond distances of the groups tetrahedrally attached to the methylene carbon atom of "the carboxylic acid anions, and is given by

-- ••••••• - - - 2 T " + T •' + T r/n1 rp C-ll T-COCT C-R [69] 1 = : • ^ —

'Die trend of the correlation between An(RdbC0O~) and T " i m

shown in Figure XL clearly [indicates a decrease in limiting equivalent conductance with increasing anion .size. More, ex­plicitly, the slope of the correlation, -10.4 equivalent con-

o ductance units per A, allows the estimation of the effect of isotopic substitution. Since C-D bonds arc shorter than C-H

o o _ bonds bv 0.003 A to 0.005 A (139), then the difference in T

m between the RGH2COO" and RCD2COO" anion pairs, AT , will not

o exceed 2.5 x 10"3 A.- This change will yield a reduction of 0.026 equivalent . cond^^ (D).-Conrpared-tc—An

If the protio compound lias a limiting equivalent conductance (in the region of 580 equivalent conductance units, then the [A0(D)/A0(H)]2 ratio will differ from unity by ca. 0.0141. Since this value is small compared to the isotope effects reported for the three 'isotopic acid pairs, the requirement that [A0(D)/A0('H) ] be much closer to unity than m (D)/m 00 is satisfied, i.e. the isotope effects calculated by isotopic slope comparison are real and significant. •

157

TABLE XXXV1

T m AND A 0 VALUES FOR SOME 'CARBOXYLIC ACID ANIONS COMPILED BY SCOTT (135)

R IN RO 12 COO''ANTON. ÎÏÏXRQ bOXT ) * • AQ (RQ 12CQQ~ ) *

11 .' 1.36 " 40.9 • CI _ . . 1.54 59.8 ' Oh 1..75 • 55.8 QRCJR ' 2.13 " ' V 32:6 Cells- \ 2.45 29.8

"Tm is computed From Equation [69]; all contributing bond o

distances are measured in A and are taken from (157).

* ''' A j values jrave units of cm-" aii-mole'-L-and-a re-taken-from— (158), v;Lth the exception of A0('CfiHcnhCOO-) 'which is taken from (102|.

138

FIGURE XI THE œRRELATION OF An AND ¥ X FOR SOME CARBOXYLIC • " " m ••

ACID ANIONS [TAKEN FROM (133)1

2. O Ê

420

41.0

40 0

390

380

•c* 370 CM 6 360 O

,~ 350 ' O 8 34-0

CM 5 33- 0

320

310

300

290

O <

C H 3 COO

o CICH 2 COO

C H 3 C H 2 C 0 0 ©

C H 3 C H 2 C H 2 C 0 0

I 20 •40 1-60 180

Ç 6 H 5 C H 2 C 0 0 \ »

200 2 20 2-40 2 6 0

T M ( R C H 2 COO ) , A

139

4-4. SUMMARY

One of the original aims of the present study was to-TTurnish further, data which, would describe...tiiC- ef£ec.ts-oJ3-.s.tpjGtui l—v-ar--• • iation on isotope effects. In a recent review by Thornton and Thornton (140) the effects of structural variation on isotope effects are regarded as important parameters in the comprehensive study of transition states. The results of the present work' provide some base Tine data for equilibria, where the advantage of relatively well-defined states is in contrast to the specula­tive 'nature of transition states. •

By way of summation, the following points emerge as impor­tant in the present study: -

(1) In-conjunction with the results of Scott and Barnes 038, 44), the present work clearly demonstrates the inadequacy of the simple inductive model in describing secondary isotope effects of the second kind. The isotope effects are not independ­ent of substituent variation, and hence the requirement of the inductive model, namely that isotope effects remain constant with structural 'variation, is not satisfied.

(2) "The trend of diminishing isotope effect per deuterium atom with increasing acidity correlated by Scott and Barnes (38, 44) appears coincidental for their results alone. The reasonably consistent correlation detailed by these authors requires that -monosubstituted acetic acids with pKa's less than 4 yield inverse isotope effects. The isotope effects reported here appear random

140

in this respect 'since these effects, are larger than those'des­cribed by Scott and*Barnes (38, 44) but the'acids themselves are stronger.

~~~(-^tyydft -which- utilizes the compari-~r " son of the Shcdlovsky slopes of isotopically substituted acid pai rs bant-(D)/mt(H>] to calculate isotope effects, is further

9

tested .in the present study. As in the earlier work of Barnes (44), the precision of this method of isotope effect calculation is demonstrateyJL to be higher than the precision associated with those methods which rely on the direct comparison of theimiqdmamic

»-• . " *

equilibrium constants [Kt(11)/Kt(Oj ]-. This method not only avoids the troublesome calculation of thermodynamic equilibrium constants, hut also largely eliminates the uncertainty associated with cell constants and limiting equivalent conductance values.

(4) The Shedlovsby TV Method emerges as a useful alterna-„ti.ve_in.othe_calculati ] '

Values -of A 0 detennined by this method appear closer to A0 values from salt data than those calculated by the Indirect Methods. Theoretical justification of this method lies in the use of a linear least squares interpolation as opposed to the extrapola­tion techniques of the iterative methods.

In conclusion, it is worthy of note that this study and the earlier one of Barnes (44) were undertaken with the rather large isotope effect determined by Halevi (341 for the phenylacetic acid pair clearly in mind. That this effect of some 12') proved

141

an order of magnitude too large in the light of repeated measure­

ment is difficult to comprehend. The investigation of the"" iso-

topc effects associated with the acids studied here and elsewhere

(.44,' 104) became an order of magnitude more difficult, as the

anticipated isotope effects of about'102 were actually of the

order of 12. Fortunately, the precision of the conductance

technique was sufficiently high to partially accommodate the T

increased demand for accuracy'.

'The simple inductive model has obviously outgrown its

Utility in describing secondary isotope effects of the second

kind. This, in conjunction with the fact that, these isotope,

effects are not amenable to a linear free energy correlation,

leads to the conclusion tliat any future investigations of these

effects must find their theoretical justification based in a

rigorous, statistical thermodynamic treatment which can account

for frequency-force constant changes between the isotopic acid

pairs and their related anions. Also, iirview of the diminutive

nature of these effects, future studies must be prepared to

develop a technique of measurement which is sufficiently precise

to allow the sa t i s f ac t on'-^ijSl ec t ion of these effects.

PART' II

aiAJ'TI-R 5

JjNTROlXlCTfON

. 1-4 2

5-1. ON THE ORIGIN OF THE MAGNETIC NQNEQUIVALENΠOF THF.

METWLENE PROTONS IN PliENiXSULF^LACETIC ACID

— — A .factorfundamental to the' determination of accurate ther­

modynamic equilibrium, constants by conductimetry .is the integrity

of the compounds investigated. Consequently, the preparation and

purification of the acicls and-their suitability to conductimetric

measurement have been given careful attention in the present

study. The preparation of phenylsulfinylacetic-2,2-d2 and phenyl-

sulfonylacetic-2,2-dv acids was accomplished by proton-deuteron •

exchange at the methylene'positions of these acids. The facility

of tliis exchange in acidi.Q.deuterium, oxide presented the possi-

.bility of rapid re-exchange ( D H) in water, which would clearly

lead" t:6'"erroneous conductance results for aqueous solutions of ,.-xX°" " f tl\esèt_a.cids. This possibility-prompted further investigation o(.

~the-exchange-reactionpn-;hich coming the chemical reactivity and magnetic-nonequivalence of

the methylene protons of phenylsulfinylacetic .acid (111, 156).

The methylene protons of. phenylsulfinylacetic' acid and cer­

tain of its derivatives were observed to exhibit magnetic"non-

equivalence when dissolved in various solvents (see Tables

X2X2XVII to XL). This magnetic nonequivalence arises as a con­

sequence of the intrinsic asymmetry of the sulfoxide group adja­

cent to the methylene, and is displayed as a single AB quartet

in the appropriate n.m.r. spectra. In 'other solvents, however,

'TABLE XXXV1I

' ' 1 -TIE 0B3ECAL SHIFTS AND COUPLING CONSTANTS OF FTlFisTLSULFINTL^a^TC

ACID DISSOLVTDt'lN VARIOUS SOLVENTS TTAKBT FROM ( 1 1 1 ) ] SOL\T2NT . cJe-Tl52AL^ (T)

C6JI 5 ! X " H B . CIR*-

CF3COOH 7 .02 - 2 44 • j 5.67 5.88 -

CF 3 CO0H/C 6 H 6 - ! 6 .36 6 .51 -

œ 3 c o o n 7 .09 - 2 51 1 5.88. i •

6 .02 -

CD3COCD3 ,

D 2 0 . * * »

7

7

.09 -

.42 -

7

7

49.

50

,1

I I

6.'09 ., 1 . 6.16 "*

CDa^SOCDa. 7 .15 - 52' j 5.99 6 .10 -

Jab: (HZ)

15

15.

14.

14.5

The. methylene protons-appear as a singlet. _ "

**Th"e chemical shifts pT 'all solutls in D 2 0 are not directly related to the t-scale.

Tie asterisk and double-asterisk retain these meanings throughout the following tables.-

SOLVENT

CF3COOH . CTsCOOH/CsHe

CD 3OX)D

CT6S0CD,

TABLE XXXAAIII

H E aiîMÎCAL' SHIFTS AND COUPLING CONSTANTS OF PilA^TLSTTFINATACrTAJiïPE

TtSAA1L\TSD IN VARIOUS SOL\TNTS [TAKE?." IAR0A1 Y111 ) ]

! - - - . *

CHF2TICAL -SHIFTS |-M

C 6H 5

; 7

.T.T' -

.14 -

JAB fH

CH 2 *

5.80-6. 83

•6.05

6. 24

NTS"

.50 - 2.65

:.15 - 2--. 55 2 . 6 8 - 2.-2

14.1 14.0

15.S

I - TABLE. X X X I X

j - ; . • • • T H E CHEMICAL S H I F T S .AND C O U P L I N G CONSTANTS O F S O D I U M PHENY L S U L F I N A T A Œ T A T E

.AND P O T A S S I U M PHENY LS EL£N0XA"ACET'ATE D I S S O L V E D IN DEUTERIUM O X I D E . [TAET3N FARUI ( 1 1 1 ) ]

COMPOUND A I

ŒBiïCAL,SHIFTS (x JAB

C6H

CeHsSOCH-COONa CHI5SeOQECOOK

6 " 3

2 . 2 4 - 2 . 5 ;

2 . 0 9

(Hz)

2 . 4 9

' 6 . 0 5

5.88

H B

6 . 2 6

6 . 1 4

lj .0

1 4 . 0

TABLE XL

THE QiTLMI CAL SHIFTS. AND COUPLING CONSTANTS OF MET HT PHENYLS UL FINYT4CETATE

SOL\T\T

CF3COOH

CF3COOH/CçH5N02

(Ql3) aCCOOH-.CD3C(X)D CDClj a i 2 c i 2

C6H5N02* Cells CCI M

CD3SOCD3 Neat (135°) •

DISSOLVED IN VARIOUS SOLVENTS [TAK2EN FROM (TBI)]

CE.H5

2.17 2.12 2.19

5

2.54 2.12 2. 20

2.46

2.65 2. 50 2. 59 Î C O

t 2.82 2.50 2.61

Q-ŒMTCAL SHIFTS ( x )

HA

5.6S 5.77 6.08 5.89 6,17

5.90

5.80 5.91 6.18 6.98 6.15

6.08

OR

6.29

6.13

6.47

6.47

6.15

Q l 3

6.15 6.27 6.44 6.35 6.52 6.34 .6.34 6.70 6.58 6.56 6.41

JAB (HZ)

15.0 .14.6 14.0'-.14.0 ' 1-3.6 14.2

14.2 •11.0 14.0

1

147

the .methylene protons appeared'.as a singlet,.indicating their magnetic equivalence. These observations invoked a preliminary examination of some underlying factors which affect the non-equi-valence-of—the-met-hy-lene-protons~l

On the assumption that "staggered" conformations are more stable than "eclipsed" ones (141), the two enantiomers of phenyl sulfinj lacetic acid give rise to six rotamers which exist as three pairs of mirror-image con formers (see Figure XII). 'Theo­retically, the methylene p rot on s aoiT confirme rs are nonequivalent, even under conditions of rapid rotation and equal population"''(142 , 143). Hence, the expected n.m.r. signal for the methylene protons .of the six mirror-image coiffonners would be three AB quartets. ' ' - ' ' .•

In contrast to the anticipated spectrum, however, only a' single AB quartet is observed for the methylene'protons of the phenylsul f iny lacejtjg_aci d_.c onf o nne rs -in .acidic-sol vents—e -.-g— -trifluoroacetic acid, and in dimethyl sulfoxide-d6. Moreover, the effective nonequivalence of the observed methylene proton chemical shifts in these solvents is large relative to their apparent equivalence when the acid is sclvated by deuterium oxide and acetone-d6 (see Table XXXVII)•

• Tlie observation of only a single AR quartet for the methyl­ene'protons of the conformer? may be explained by one of the following (144): , '

(1) The energy difference between the conformers of long

148

/ FIGURE XII NEVJMAN PROJECTION- DIAGRAtS (WEWED ALONG THE S-C BOND) OF

THE THREE PAIRS OF MIRROR-IMAGE OCMPORMERS* FOR THE > TWO PfflNYTVSlJLFliS ^

0 0 0

COOH ( HA H B

I I a l i b l i e

*Conformers la and lia, lb and lib, Ic and-lie are mirror images. The methylene protons are arbitrarily designated as H^andHg.

14 9

lifetime is so large that only the most stable is present. (2) An equilibrium exists between the conformers in which

each conformer is sufficiently long-lived and abundant to give iJLS-j n-n.. m.x.-~spectrumThat—t-he-obser\red-spectruiïï li(tnvs__.only] ( a single AR quartet implies the spectrum of any one of the con-formers is the same as' that of #any other. The observed spectrum tlien is a simple superposition which represents all'the conform­ons.

(?•) Internal rotation of the methylene, group and/or inver-s .ion of-the electron lone pair at sulfur occur at a sufficiently rapid, rate for the effective chemical shifts (screening) and^/he spin coupling constants to be averaged.

•The effective nonequivalence of the methylene protons of phenylsulfinylacetic acid, in any solvent at a given temperature is a Inaction of. the. relative populations of the conformers such that ' • . — — ~

r 70] <-6HA effective> = P^H + P26H

•'SHp effective + P^Hdy

P72d .<('<5l!A - SHB) effective> = Pi(yHA] C -d!;,- ! + P;> (<5HA, «5HB

+ P 3(6H A 3 : 5H B 3)

-where <5 If\ and ôllg. are the- respective chemical shifts of the

150

JThc i arge-e-Me etd ve-rtcp displayed when the acid is solvated by acidic solvents or di-methyl sulioxide-d6 relative to their apparent equivalence in deuterium .oxide and acetone-dG (see Table XXXVTI) is not readily explained, but may lie in a consideration of the following possibilities: . -

• (1) The nonequivalence of the methylene protons is a -con­sequence of the intrinsic asymmetry of the adjacent sulfoxide

y —^

group and it may he differentially enhanced bj/ ehanges in magne­tic anisotropy incurred from solute-sol-véjalT'interactions at -specific sites on the solutge m'dlecule. ' (2) The populations of the three conformers in deuterium ° / j y S ^ — " lence of H^ and Hp appears small, due-to a cancelling effect in

T

tlie tenus of the averaged sum {see Equation- 1.72]} . However, specific solute-solvent interactions, which may exist when phenylsulfinylacetic acid is dissolved in acidic media (or dimethyl sulfoxicle-d-) , could favour a particular conformer. These interactions could also_ restrict internal rotation and inversion at sulfur, such that interconversion between the con-formers is inhibited. Hence, the-.cancelling effect exhibited in deuterium oxide and acetone-dR mav be reduced in acidic media

. \ ' i

methylene protons of conformer n, < (SH^ - clip)effectr"e> I s the observed nonequivalence, and \\, P 2 ) and P3 are the fractional populations of-the conformers. \

and dimethyl sulfoxide-dr, as a consequence of alteretKconformer

populations .• _

[3)- The inherent-asymmetry of the sulfoxide group mav be

•des-t-royed-by-th e^omTtxtor^

deuterium oxidp ajid acetone-dG in which the methylene protons

experience similar or equivalent magnetic environments Cc.f.

(145)]. Also, solvation-fby the addition of'deuterium oxide may

dcjstroy the inheixmt asymmetry of the sulfoxide group in much

the same manner as water is purported to do- in the case of anal

ogous selenium and tellurium compounds (146). •

The n.m.r. spectra of phenylsulfinylacetamide dissolved in

various solvents (sec Table XXXVTII) are similar to"those of

.phenylsulfinylacetic acid in deuterium-oxide and acetone -d 6 .

Hie AB quartet of the methylene protons is unresolved and appea

as a singlet, but coupling between I by and Hp in trifluoroacctic

acid _(JAR_j^_1.4 .1-1 Iz)_and-dimethyl-sul-foxide-d-e~ (^-=-1378-1 lz)'

is evident.

For the methylene protons of sodium phenylsulfinylacetate

dissolved in deuteriiDTi oxide at 40°C, the effective nonequiva­

l ence is. 9. 7 Hz (see Table XXXIX) . About 94] of the acid is

undissociated* in deuterium oxide, but the sodium salt is

assumed to be present as ions. The chemical shifts of the * „ ,>

-Based on pKX = 2.66 inYl'cO (46). \

i

methylene -protons in both the acid and tire sodium salt are de­

pendent upon the electronic configuration of the solvated

spec res , and the negative_charee~Qf tiie~phenvd-su ^ anion.will certainly perturb the electronic configuration. Hence, any comparison of tire nonequivalence of the methylene protons in the acid and sodium salt is not strictly valid. The phenylsulfinylacetate anion could well be a "structure maker" in aqueous solution, analogous to the acetate ion (147) which has a Bingham.value* of -21.4.- This implies that the phenyl­sulf inylacetate anion is bound by a more rigid solvent shpTf-^^ in deuterium oxide than the undissociated acid.

The temperature dependence of the chemical shifts for and Hp, of sodium phenylsulf inylacetate in deuterium oxide was examined to provide additional information about the solvation

of the anion (see Table XL I and Figure X11I)_. If conformational interconversion is rapid, tire chemical shifts for IBy and dip will be averaged as shown hy Equations [70], [71] and [72]; and if the conformées have different energies,' the ratio of IB-.PjHT will be given by .

r-7-r r> n .n - "Ei/kT -E?/kT -E3/kT [7oJ P1;P2:P3 = aje : a2e : a3e '

"A'measure of molal fluidity elevations of ions proposed by E.C.

Bingham (148).

TABLE XL I

TTE VARIATION OF TIE CHEMICAL SHIFTS FOR THE M E M Y L E N E PROTONS OF SODIUM PIJEN Ï'L S UL FI NT LACET ATE

(50 ± BY WEIGHT IN DEUTERIUM 1 • OXIDE) KTTH TEAIITRATLIPAE [TAKEN FROM (111)1

mg^RATLIRE, \G

90

80

60

50

40

30

20

10

0

c H A - o H B , Hz

8.3

• 8.2

.S.5

9.1

9.5"

9:7

9. 9

10. 5

10.7

10.8

11.2 •10

THE VACATION OF j 6H^ FIGURE XIII .' . . \

- <5Hr| WITH TF^EMTURE IN A DFTjTTRIUk-OXIDE

N

' - %N SOLUTION OF SODIUM PrlT£ I 5lJLFIi [ TAKEN FROM (111) ] •;]

N ! / i / - : 1

N

>

i I I

y : . . " . •• • •

':.. ' ' - •

! ^^^^^^ ••• v

i 1 I " i i i i i i i

I

1 .0 0 20 4 0 6 0 8 0

i ' *

j TEMPERATURE, °C

100

155

where a ;, a 2 and a 3 are usually different for each of the con­

formers, and will be only slightly temperature dependent. Thus,

since the effective chemical shifts of Hy mul'dlg_arc^tenpexature.

dependent, i.e., nonequivalence changes with temperature, then

conformational intercoriversion 'is indicated (144) .*

The adoption of a single, favoured conformation by the'

anion in aqueous media is not unreasonable. The favoured con-

former clearly would be the one in which the repulsive tendency

between the electron lone pair on sulfur and the negatively

charged carboxyiate oxygen is satisfied by maximum separation.

This additional barrier to\conformational interconversion, by

internal rotation and/or inversion, provides some explanation of

the large effective nonequivalence exhibited by the methylene

protons of the aqueous anion relative to their apparent equiva­

lence in aqueous solutions of the largely undissociated' acid.

Clear]}', the barrier to conformational interconversion would be •

less in the case of the acid, as evidenced by the apparent

equivalence of the methylene protons due to chemical shift

averaging, [see above, p. .149) .

*More detailed analyses of solvent teffects on analogous

systems have been discussed by Nishio (149, 150, 151, 152) and

more generally by"Roberts et_ al_. (153).

156 V

The spectral temperature dependence of the effective non-

'equivalence of the methylene protons1 in the aqueous anion may

also be a conseguejice^^ .... ...

If the intrinsic asymmetry of the anion is small, then the large - .

effective nonequivalence exhibited by the methylene protons could

result from enhancement of the anion asymmetry by solvation at

specific sites. As the temperature is increased these solute*

-solvent interactions would be diminished, and the effective

nonequivalence of: the methylene protons w;ould approach a minimum.

.' , The n.m.r. spectra of methyl phenylsulfinylacetatc (see

Tables XL" and XLI1 to XLVTI) indicate that the effective chemical

shifts of b! and H^, the methylene protons, are very sensitive

to the nature of the solvent and the solute-solvent ratio but are

only slightly affected by temperature .changes.

The significance of specifie_sc3l\yent —

the effective chemical shifts of the methylene protons of the

ester dissolved in pivalic acid is demonstrated by the fact that

'magnetic nonequivalence is exhibited only when the mole ratio of

solvent to solute is 2:1 or greater. This does not preclude the

formation of: symmetrical' solute diners at high concentration, but

in view of the absence of spectral ten'ip*er_ature dependence, dimer-

ization appears-unlikely and rapid interconversi^n of the rotamers

is Indicated, V,

, TABLE XLIT

T E ŒBÏÏCAL SHIFTS AND COUPLING CONSTANTS OF THE XETlTi'KErlE PROTONS OF METPPÏT PBENYL S IILFI NT LACETATE

TFTTERXTURE

( ° C )

43

60

80

100

(30 t 1% BY VTTC1TT) DISSOLVED IN ACETIC ACTD-cK [TAKEN FROM (111)2 .':

C 6 H 5

2.13 --2.50

2.13 - 2.52

2.12- 2.52

2.11 - 2.55'

• M CAL S H I F T S (T) • •

-5.90

5.92

• 5.93

5.93

6.08

6.05'

6.05-

6.07"

ai 3

6. 53

6. 33

6. 33

6.32"

A B " ( H Z )

' 14.2 i

(. 14.0 I"

2 1 4 . 0 \

.: 14. 0

Ln

TABLE XXIII 1

} ^ -THE ŒIB1ICAL SUFFIS, COUPLING -CONSTANTS, AMD DIFFERENCES BETWEEN THE aiTiMICAL SHIITTS OF THH " " • • - t. ! ,

NETHYLENE' PROTONS OF' METHYL- PHENYL SULEI NT L A Œ T A T E 'DISSOLVED' IN PIYALIC ACID AT 55°C [TAKEN

(ahïiCœOH

^PLES x 10''

45.06

• 59.16

. 34.27

29.37

. ' 24.4S

;• "19.58

'14.69

9.79

4.90 .

C Ê HS S O C H I C O O Q R

FROM (111)3

MOLE RATIO ŒE1IÛAL SHIFTS (T ) ] ÔH A Î-DLES : v 10" % (Y j Sx/Y. . J I A 1 1R CH2* (Hz)-

? 52 17.9 ": 5.95 6. 20 "l5.0 5 04 7.8 5.99 6. is • 11.3 7 '57 • 4'. 5 6.00 6. 16 -. -. -v A-5

10 09 '2.9 5.99 6. 12

12 60 1.9 6.OS 6. 17 . • - Y .5,4-

15 1.5 - - 6.10

17 65 0.83 " - - 6.-07

20 IS 1 0.49 6.05 -

22 70 0.22 - d ' . 6.06 -

TAB'(Hz)

14.0

14.0

14.0

-14.0

T A B L E X L I V

THF, OHE? II GAL; SHI F I S , -COUPLING CONSTANTS, AMD DIFFERENCES BlTl'.EEV TIE Q E I I C U PJBIFTS OF THE

IETIDTLEÎ-TE PROTONS OF METHYL RIŒ.WLSIILFINYLAŒTATE DISSOLVED IN PI V.ALT C ACID AT 65°C

( O h ) 3CCOOH

[TAKEN FROM (111) ]'

C6H5SOa-l7CCOCrl3 MOLE MI 10 CHFTTICAL SHIFTS AT)

IDLES x 10"", (X) IDLE5^ 10" \ (Yj 5 H A ' 6HB-I J AT. (Hz)

X/Y H

4 5.0b

39.16

54X27

29. 57

24.48

19.58

14.69

9.79

4.90

2. 52

5.04

7.57

10.09

12.'60

15.13

17.65,

20.18^

22.70

IT 9

.7. S

4.5

2.9

1.9 .

•1.3

0.83 '

07 49 7

0. 2lT •

H au*

5.96 6.21 5.94 6.13 6.00 6.16

6:05.. 6."iS

J T :

15.1 11.4 •9.4 7.8

6.09

6.10-

6.09

6.09

-.6.09

15.9 14.2

14.0 •

14.0

14.2

14.1

14.0

14.0

14.1

TABLE XLV

THE 'CHEMICAL SHIFTS, COUPLING CON ST AMI'S, ATP DIFFERENCES BETl'.EEA' TEfE CHEMICAL SHIFTS OF THE I ' ' ' i t o

METHYLENE PROTONS OF MOTET P1ENY LSUL FI NT LACET AT E DISSOLVED INTTYALIC ACID AT (75 C .

(QHhcecof

[TAKEN FROM (111)]

C s H T O n T C O O C T MOLE PATIO QEMICAE SHIFTS (A)

MOLES x 10"\(X) MOLES 2 c 1 0 - " ,fY)i X/Y "A H?, a E - •(Hz) !

45.06 ' 0

I 52- • 17.9- - 5 .97 6.22 14.6 2

'59.16 5 04 7.8 6.00 6.19 - n - 3 _ -. 54 72 7 57 4.5 . 6". 00 6.16 9.7

29.5 7 10 09 i !

2.9 6.05 6.16 7.8 '

24.48 60 1 . • 1 . 9 - 6. in • - ,

19.58 - • 15 15 " J - 3 - - 6 09 -

14.69 17 65 0.85 - 09

9.79 20 IS 0.49 - - - 6. 10

.4.90 7 ? 70 0.22 - - •6. 09 -

I

14.0 14.0' 14.0 14.0 - 14.0 a 14.0

\

" - - TABLE- XLVI / ' ^ |

' - • ' X:

THE ŒiBlICAL SHIFTS, COUPLING CONSTANTS, AND DIFFERENCES BETWEEN TIE C4TL7XTCAL SHIFTS OF TIE

MET1ETENT PROTONS OF MET!HA lilNTLSULFlNTLACETATE DISSOLVED IN TIVALIC ACID AT| S5°C r

i i - ' C T \JKEN FROM ( 1 1 1 ) ]

\

( ;aT 5 ) ' 3 coooH

1 I C s i u s o a E c n o c i i s ! MOLE RATIO EHBIICAL SHIFTS |Tj |6HA - cHj>

-•JAB 0i=)

MOLES J c - 1 0 " " , c x ) MOLES > i io^TO'0 ' X/Y H . v _

1 Hp CH 2 * - • (Hz) :

-•JAB 0i=)

45 06 ~>

i

«. ! 17 9 6 .00 6 . 2 3 - 1 5 . 9 ; 1 4 . 0

59 16 5 04 7 8' 5.99 6 .18 - 1 1 , 2 7 1 4 . 0

54 27 - 57 j 4 5 6 . 0 3 6 .19 • " ' 9 . 7 ^ Up •-; '13,. 9

29 57 10 09 ' | 9 .6 .06 6 .20 - " 8.2- ; 1 3 . 8

24 48 ' 12 60 | 1 9 •- 6.119 \ 1 5 . 9

• 19 58 15 15 j 1 5 6.09 1 4 . 0

14 69 1" 65 ! !

0 .85 - - ' ' 6 .09 - 7 -

g 79 20 18 ^ 0 .49' - ' • - 6.09 -- - '

4 90 0 2 ? - 6 .09 . - • - ' •

I

TABLE XLVIT

THF- CHEMICAL SHIFTS, COUPLING CONSTANTS, AND DIFFERENCES BETWEEN THE QiEMICAL SHIFTS OF.TE METIYLENE PROTONS OF METHYL PIeTTSULITNTLACETATE DISSOLVED IN PIV'ALIC ACIB AT: 95°C

(YAH 3) 3CCOOH MP LE S x 10-",(X)

Ce.Hs.SOa-LOAOaL

MOLES x 10'\(Y)

[TAKEN FROM (111)3

MOLE RATIO CHEMICAL SHIFTS (-

X/Y H A HR ( T V

CHA - AIT

iilLL

45.06 2 52 17.9 6.00 6 23 39.16 ' 5 04 - 7.8 6.02 6' 21 34.27 7 !

57 ! 4.5 6.04 6 20 •

29.5" 10 09 J 1

2.9 6.05 6 18

24.48' 12 1

60 j 1.9 6.09 6 IS

19.58 15 13 '1.5 - -6 11 14.69 l 7 65 . • 0.83 - 6 11

9.79 20 18 0.49 - - 6 10

4.90 22 70 1 0.22 6 09

. 15.9 11.9 9.S

"* 5.6

JAB W

14.0 14.0 14.0 15.9' 13.5 15.5 15.9 '

a--

. 163 m

In sinranary, although comparisons of the chemical shifts'of! the methylene protons of phenylsulfinylacetic acid with those of its amide, methyl ester and sodium salt, may not he strictly valid,

,. a-generality of their collective magnetic behaviour appears to, be that the effective nonequivalence of the methylene protons in

; each is a function of solute-solvent interactions. The major in­fluence of these interactions is summarized in the following two considerations: \ .. • / (1J The intrinsic asymmetry of the acid and its derivatives,

which may be. inherently smal1•[c.f. (154)], is enhanced by speci­fic soJutc-solvent interactions. This.solvation almost' certainly lends greater as>Tnmetry to the .solute and the resulting changes in magnetic anisotropy arc evidencedJby corresponding changes in the effective nonequivalence of the methylene protons.

The apparent equivalence of the methylene protons of the

—ac id- 'di sso lved-in~ya'riws^oIv^ts ' (acetone-d6, chloroform-d,.

benzene-dp', carbon tetrachloride) is then explained by small • n

solute-solvent interactions which cause no appreciable enhance­ment of the magnetic anisotropy of the solute and hence the methylene'protons appear equivalent.

The apparent equivalence of the methylene protons of the acid dissolved in deuterium oxide, however, is not easily ex­plained in tenus of small solute-solvenj: interactions. Although dimerization has been postulated in other sulfoxide systems (155)

« 1 6 4

y

to account, for the disappearance1 of magnetic nonequivalence in \ A

deutcriimpoxKle, the collapse of the AR quartet n.m.r. signal for the methylene protons may be a consequence of specific solvation 'which'."destroys'the inherent sas}mimetr>r of-the sulfoxide group [c. f. (146)]. , ...

In view of the insignificant spectral (_TIOT

ponding changes in temperature and concentration, the formation of dimcrs of the acid (trifluoroacetic acid,- acetic acid, and dimethyl sulfoxide-d6 solutions) appears unlikely, llic large effective nonequivalencc of the methylene protons of they acid in these solvents is amenable to the generality of increased-magnetic anisotropy through solutp-solvent interactions*.

(2) The effective nonequivalence of the methylene'protons of phenylsulfinylacetic 'acid and its derivatives'is also a func­tion of the relative populations of conformers. 'The relative populations are in turn dependent upon the" barriers to conforma -tional interconversion, and.the differences between the respec-five barriers are undoubtedly influenced by solute-solvent inter­actions. Since conformational interconversion occurs through

*These interactions presumably take the form of hydrogen bonding, and' although the absence of spectral temperature dependence in the effective nonequivalence of the methylene protons-does not preclude the formation of hydrogen bonds, any'such bonds formed must be exceptionally strong. •

165

internal rotation and inversion at sulfur, the differences in the rates of these processes miis.t in part be governed by. solute-solvent interact ions . . . \ • . , - ———~- •—

This concept is supported by the large effective' nonequiva-lence displayed_ in highly acidic media and dimethyl sulfoxidc-dj, and the apparent equivalence of the methylene protons in solvents-of lower diel-ect-fic and hydrogen bonding capacit}'. ' Solute-solvent

I interactions presumably are Stronger and more specific in the - , .• " - V b • former than in the latter, and hence increase the barriers to conformational interconversion by inhibiting' internal rotation and inversion at sulfur.

166

5-2, . PROTON - DEIRTERON' EXCHANGE RE/\CTIONS OF PlIEmsULFIWTNACETIC

ACID -

Phehylsul finylacetic acid-2 ,2-d2 has been prepared and a

qualitative kinetic investigation of the deuteron to proton re-

-exchange"process at the methylene position of the acid has been

examined (1-56'J. The n.m.r. 'spectra of the recovered.samples m ,

moist trifluoroacetic acid and dimethyl sulfoxide-d6 revealed

four-peaks appropriate to the methylene pro'tons.of the protium

acid together with two^further relatively broad singlets close

to, but which did nonexact ly correspond with, the shifts of the

meth>Te|ie protons of/ the protium acid (see Figure XIV). The

magnitude of the latter varied with time, reaching a maximum and

then diminishing as the conversion of the deuterated acid to the

protium acid-progressed. These twro broad absorptions were assigned.

-to-the~s'i.'x~fûtiâïîiërs of the two diastercoisomers (see Figure XV)

formed in ti\e exchange. ,

Theoretically, six different absorptions should appear for • .

the ctiastereotopic protons of the ro tamers, but, only-two peaks

were_ observed. This observation is similar to that for the sol-

vated protitun'acid. • The two observed peaks are broadened, pre­

sumably by unresolved (triplet) cotrpling to deuterium in each,

case, and the unequal magnitude of the two peaks has.been ascribed

in analogous cases to differing exchange rates for the two methyl­

ene douterons (157).. '

167

FIGURE XIV PORTIONS OF N.M.R, SPECTRA OF PARTIALLY Ttf-EXQWGm

PHENYI^UIT^^ A C I n AT VARIOUS TIMES [TAKEN FROM (111)]

•c 168

COOD H D

Io lb ~ - • < — ic

II a II b II c

NEWMAN PROJECTION D I A Q ^ ^ THE S-C BOND) OF-SIX-DIFFH3E^ 2-d"

ACID DLASTEREOISOMERS [TAKEN FROM (111)]

FIGURE XV*

. ' 169' t'

Rauk, Wolfe, Buncel, and Moir (158, 159) have reported similar observations•concerning the reactivity of the methylene

.'protons..of benzyl -methyl.-sulfoxide-towards- isotopic exchange in" ' LM NaOD/DgO, arid have shov.ri that the methylene protons in tiris .compound differ in reactivity by about a factor of fourteen. The differences in the chemical shifts and the coupling constants for the methylene protons'were.similar in phenylsulfinylacetic acid and benzvl methvl sulfoxide, and the only significant factor "winch influenced the observation of the diastereoisomers by n.nwr. was the relative rates of exchange of the two protons or douterons (156). It was consequently concluded jhat the methylene protons of phenylsulfinylacetic acid in acidic\rqueous media are closer in reactivity thaji those of benzyl methyl sulfoxide in IM NaOD/D?0, since both the diastereoisomers were observed Kith the former

-compound—whercas-only^ topic proton was observed in the case of benzvl methyl sulfoxide.

An explanation of the preferential exchange process of the methylene protons.of benzyl methyl sulfoxide has been offered .by .Wolfe y .yrl_. (158, 159). From dipole moment studies and n.m.r. considerations these workers concluded that the conformation displayed in Figure XV] is favoured in both nonpolar and polar solvents and that Hy is stercospecifically(exchanged. This con­clusion wras further augmented bv ID calculations put forward bv Wolfe, Bauk'--'ancl Csizmadia (160) on the, relative stability of the

FIGURE XVI

FIGURE XVII . A-NEWMAN ' PROJECTION -piACT^ÔFT'

SULFOXIDE VIEWED ALONG THE C-S BOND

H e 0

A NBVMAN PRfJJECTION DIAGRAM OF BENZYL METHYL 'SULFOXIDE VIEWED ALONG THE C-S BOND

171

hypothetical carbanion. *-' ^ai2-SO-H. They concluded that the most

stable conformation is that with the carbon lone pair orbital

-gjru/cd and the • sulfur lone pair

Mother energy minimum occurred for the carbon lone pair trans •

to the sulfoxide-oxygen bond and gauche to the sulfur lone pair,

but the conformation in.''wlrich the carbon lone pair is trans to

both the sulfoxide-oxygen'bond and the sulfur lone pair occurred

at an energy maximum. In a further work of wider scope, 'Wolfe ••

f161) has enunciated a generality which states,"in agreement with

the predictions of ab initio molecular orbital calculations, bat

not with' current qualitative and phejiomenological concepts, such' y i*

species exhibit a 'gauche effect', i.e., a tendency to-adopt that

structure which has the maximum number of fauche interactions he'-i—• - •

taxe en the adjacent electron pairs and/or polar bonds".

Ni_shio_.(142.,_l50.,-.l Sl-,-y S 2)-dias~ reported" thatym^

of the type R-CyHy-SO-Gl2 -CGFL-R' the prof on which is trans to

the sulfur lone^yair and gauche to the sulfoxide-oxygen bond is

less sensit ivTF-to change in the electronegativity of the R'

substituent than the proton which is cis to the sulfur ne' pair.

The chemical shift of the proton trans to the sulfur lone pair

(lip) is also more sensitive to acidic solvation, as shown in

figure >TVII. From an examination of the stereochemistry and

differential solvent effects on the n.m.r. spectra of these

rxpes of, compounds, Nishio has attempted to' unambiguously assign

t h e " m e t h y l e n e p r o t o n s a n d l i a s p r e d i c t e d t h a t H p , t h e p r o t o n g a u c h e

t o ' t h e s u l f o x i d e - o x y g e n b o n d a n d t r a n s t o t h e s u l f u r l o n e p a i r , i s

p r e f e r e n t i a l l y e x c h a n g e d . '

H u t c h i n s o n , A n d e r s e n , a n d K a t r i t e k y ( l o f ) h a v e e x a m i n e d t h e

. • _ b a s e - c a j a i y : . e d l i y d r o g o n - d e u t e r i u m " a T v C h a n g e ' A o f t h e o - s u î f ï n v l p r o ­

t o n s i n t h e . c o n f o r m â t i b n a l l y r i g i d e i s - a r i d t r a n s - 4 - p h c n v l t ô ' t r a -

h y d r o t h i o p y r a n - 1 - o x i d e s . . T h e o r d e r o f i n c r e a s i n g p r o t o n a c i d i t y

• a d j a c e n t t o a s u l l a h y l ' g r o u p w a s c o n c l u d e d t o b e ( a i t r a n s . t o t h é

_ • s u l f u r - o x y g e n b o n d a n d " g a u c h e t o t h e s u l f u r ] o n c p a i r , ( h i g a u c h e

t o t h e s u l f u r - o x y g e n b o n d a n d t o " t h e s u l f u r l o n e - p a i r , a n d ( c ^

; g a u c h e t o ' t h e s u l f u r - o x y g o n b o n d - a n d t r a n . - t o ' t h e s u ] f u r l o n e

'•" . H ' u ' . ' ' { , y " A - ' - .

T h i s \ o r d e r o f . a c i d i t y i s n o t i n a g r e e m e n t Kith t h e c o n c l u - '

A'-ions o t i H s b i i o a n d o n l v p a r t i a l l v c o n f i r m s t h e t h e o r e t i c a l » a r » > u - '

m e n t s o f W o l f e , K a u k .-IIKL-CSJ r m a U i a ( 1.60 J- 1 6 3 , l o - l f ' ; - K a r r i t c k v

. a n d c o - w o r k e r s / a g r e e t h e r e a r e t w o p o s s i b l e e n e r g y m i n i m a , b u t

—thaftlve~orarr"'\TT"âcTlif> ; o f t h e - t - s u l - f i n y l p r o t o n s p o s t u l a t e d b y

f . o l i o e t _ a l _ . J o s these- m i n i m a s h o u l d - b e I n t e r c h a n g e d , i . e . , t h e

- t . ' - • - L ' • «T '

". a s t - e x c l i a n g e V p r o t o n j s - 1 o c a t e d - t r a n s t o t h e s u l f u r - o w e e n fond a n d g a u c h e t o t h e s u l f u r - l o n e ' p a i r , r a t h e r t h a n g a u c h e t o b o t h

t h e ' a s v m m e t . r i c c o n t r i b u t o r - .

f x a ' s t u d v c o ^< M i a t o f K a t r i t z k v a n d c o - w o r k e r s , - -

B a l d w i n , l l a e k k - r , -v' ' ! : a \ ' o r e p o r t e d t h a t d e u t e r i u m

\ - - • —•—— . • o e ^ , ' h o c c v e r , t h e l a t e r c o m m e n t s o l K o l i e e t ' a l . i l.(-,o ) . . h

• t

e x c h a n g e . o f theoretically m o r e l a b i l e p r o t o n . i n ( S ) - b e n z y l

m e t h y l s u l f o x i d e v i e f . l s t h e D O - c o n f i g u r a t i o n a t t h e b e n - v i b-h • • • , ) . " .

c a r b o n , a t o m , a n o b s e r v a t i o n o p p o s i t e t o t h a t o f tte-,1 ) e c t . a l .

flic r e s t O t s " " o f " b a l d e i i ï , d l a e k l e r , a n d S c o t t . - a ] , p e a r t o c o n h p n

t f i e i d X o n v a t i o n s o l " K a t n t z k v a n d c o - w o r k e r s , i n , t h ; i t t h e m o r e

l a b j d ' e g m t o n o f t h e m e t h y l e n e g r o u p i n b e n z y l s n e t h v l s u l f o x i d e .

i s a p p a r e n t l y g a i i c l i e t o t h e • s u l f u r - o x y g e n b o n d a n d t r a n s ' t o t h e

s u ! f u r i o n e .p.') i r .

l a v i e v . o f t h e - r i b o y e , s p e c u l a t i o n m i g h t l e a d - t o t h e c o n c l u ­

s i o n t h a t t h e m o r e l a l y i - l c p r o t o n o f t h e m e t h y l e n c ' g r o u p ' o f

p h e n y l s p l f i n y l n c e t " i c a c i d i s g a u c h e t o t h e s u I f u r - o x y g e n , b o n d a n d

•i

I*'ans t e t h e s u l f u r l o n e p a i r . ' H o w e v e r , t h e e x c h a n g e p r o c e s s

h n s M b u s f a r o n J y b e e n c o n s i d o s c d . a s a p s e u h o - f i r s t , o r d e r . r e a c t i o n

i?T a l k a l i n e i i i ' .d i a c l n n j , i n which t h e f o R i f a t i o n o f ' t h e m o s t s t a b l e

' . ; • ' ; " o y -

c a r b n r . i o n r e p i e s e i i t . s t h e l e a s t c n e r g e t i c t r a n s i t i o n s t a t e . , o n t h e •

' f é r t â T i ^ p a ' t h r . a v . I f o l f e , R a u l , a n d ( i s i z o a d 1 a . 1 I P C , . b ô ,

h a v e b a s e d t h e i r n b i n i t i o MO c a l c i n a t i o n s o n u n s o l v a t e d

s p e c i e s - a n d . K a t r i t e l e c t _ a d . ( 1 h d ") h a v e o n l y c o n s i d e r e d s o l v a t i o n

i n a g e n e r a l . q u a l i t a t i v e s t a t e m e n t , i n t h e c a s e 0 f t h é h y d r o g e n -

d e u t e r u u i i e x c h a n g e r e a c t i d j L a t " t h e m e t h y l e n e g r o u p o f p h e n y l s u l -

f i n y l a c o g j c a v i d t h i s s i i : p l e a p p r o a c h t o t h e r e a c t i o n m a } ' n o t l i e

e n t i r e l y j u s t i f i e d , s i n c e y e c i f i c ' s o l g e n t - p a r t i e . i p a r . i o n i n t l i e

i v a c t i o n ^ i s - p o s s i b l e » 1-15., '1-16J a n d m a v h e i i x U c a t e d . b y . t h e

174

(.1) Ihc apparent equivalence ' of the methylene protons when phenylsulfinylacetic acid is dissolved in. water'may indicate the formation of a solvated species in which the intrinsic-asymmetry

..o~P7thc.. sulfoxide -.-group yis-destroyed". """ '

(2.) The difference in the rates of exchange of the two methylene protons appears^much smaller for phenylsulfinylaceViç-ac:id than tor those of sulfoxides previously reported. This may rellect a simple dependence upon the acidity of- the exchange media but does not exclude/'specific deuteron/deuterium,oxide participation. • . .

4

5-3. .N.M.R. SHiCTKA OF PARTIALLY EXCHANGED. PliraS'YI.SUI.FIiWLAŒTIC

' A C I D .

• v I From an examination oR n.m.r. spectra of partially exchanged

phen)Msulfanylacet]cfaçi^R7it has been noted that the shifts of

•the two broad' peaks Jféj •r^sVnih^ct^e plienylsul J; j ny lacet ic - 2 -d •

acid d i a s ^ idièn dissolved in dimethyl

sul Loxide'-Xf relatTy^ j n trif likrroacet ic acid

flSP). This changé <J8K$5SJ|i0^j^:-eviderit since 'the' shifts were • ; o d i ^ ^ -\ '

•of unequal magni ' hseifâ e'l'.o'f unecVial reïacfivitv. N.m.r

measurement^ on solutions',Sf/gFi n' sulfinvlAcetic acid'in Varvine

amounts 01 triiluoroacetYÇ <ac RF and dimethyl, sùd_fo.xide-dc were •V

recorded (see Table XLVIILand Figure XV!]I), and the followinp .

were- proposed to account for the observed phenomenon : '.

(1) The chemical, shifts, of II. and IL actual lv coalesce,

cross, and then interchange positions as the amount of one sol-

-vcnt"'(CF7CCX?H) increases .relatave to the amount of the other

1 ClyStX7R;. ) . Uns "crossing" of chemical sin ids may result from

the. change of .one preferred conformer in CfNCOOH to another "in

ClyAOCLA . Although equivalence of H, and IL is theoretically' «- ' A „ b • -

J i i y p s s î.blc „ coincidental équivalence, of 1 ly .and H|;, ma\r occur due

to a cancelling- effect in. the n.m.-r'. signal (see liquation [721 }

as the- - relative populations of the con former's are altered bv a

gradiuai change in solvatioiV.

•(2'J Tlie chemical shifts of IIA and H ? are interchanged in

trifJuoroacctic acid relative to their positions in dimethyl

subfoxrdevdc ckn p spccifie solvation -differences vhicdyfrcsult

T A B L E XLY2III

TEÎE CHEMICAL SHIFTS] AND COUPLING CONSTANTS OF TTiE METIETENE PROTONS )F PI-EN YL SUL FI Ni' LACET IC "AC 1D (25 ± 1] BY V£IGHT) DISSOLVED IN MIXTURES OF

TRIELU0R0AŒTIC ACID AND DIETHYL SULFOXIDE-d6 [TAKEN FROM ( 1 1 1 ) ]

SOIAIAT COMPOSITION

'cCD-iSOCDs CFaCOOH MULTIPLICITY 12HEMICAL SHIFTS (tj

ion - • 0 quartet \ ' .5 96 . 6 .14

90 - 10 quartet ! t

99 6 .14

8 0 , 20 quartet . " 6 02 6 .13

' " 0 - 50 singlet -

60 40 singlet' -

50 50 quartet 6 00 6.11

40 60. quartet 5 92 • 6 .04

AO 70 quartet 5 8 8 - 5 ,99

20' 80 - quartet ' • 5 68 S. SS

10 .90 .quartet •• • " 5 6 7 ^ — 5.88

0 100 quartet ) -a 6 7 V J 5. SS

ai2:

6 .11

6 .11

JAB (HZ)

1 4 . 2

147 2

-14.2

14 .2

14 .1

.44.1 I 14.0 lis.2 ; I ; 15. i

T 5.1

177 • • •

\ FIGURE XVIII > THE CHEMICAL SHIFTS OF THE METHYLENE PROTONS OF PHENYI^FINYIACETIC ACID IN MIXTURES OF TRI -RUOROAŒTIC ACID AND DI^QHYL SULFOXIDE-de

[TAKEN 'FROM (111)1

IOOO -

9 0 0

8 0 0

7 0 0 to O—600 o O CO m 5 0 0 Q O

H B

0 i

i

4 0 0

3 0 0

2 0 0

I 0 0

0 0

5-60 5-70 5-80 ^ 5-90 6 0 0 610 \ 6-20

f T

<

_L

0 0

100

2 0 0

3 0 0

40 0 x o o -\ 50 0 °m a. o

6 0 0 y

to o '

- '80 0

90 0

100 0 e

CHEMICAL SHIFT, T

17S

in different, magnetic anisotropics for each of the solvated species. Assuming' that dimethyl- sulfoxide-d6 is more "basic" Jtjiajn ^

interactions, in the form of intramolecular and intermolecular hydrogen bonding Cc'.f. Pas to e_t_ al. (15, 113)], may well be •significant irw.the molecular description of.the solute in thiss solvent. . -

.As the concentration of trifluoroacctic acid is increased in a solution of phenvlselfinvlacetic acid and diir.ethvl"sulfox-ide-d6, the latter may be removed from the sphere of solvation. . ,, As tliis occurs the observed differences in the chemical shifts of. 11 and lip will tend to a minimum, exhibiting apparent coal- \ eseence if the'asymmetric contribution of the sulfoxide- group is inherently small [of. (154)]. At this point the phenylsulfinyl-acetic acid i s p r - c y i i n y i ^ — -methyl sulfoxide-dG complex, which must be'quite different in magnetic susceptib.ilitv and drpole moment than either of the

* • . ' • '

parent solvents. •• » • . • •AS •

As 'the trifluoroacetic acid becomes more abundant thai 'the •-/

dimethyl sulloxide-uV* specific solvation oi undissociateçl,1çhenyl-sulfinvlacetic acid by the former predominates, and probably takes the form pf hydrogen bonding to the-carboxylate.and sulfoxide oxygens as described by.Oac et_ ay (1.45), • Hence, the apparent •'

\ ' coalescence disappears and the chemical shifts of iy. and by exhi-..

V bit nonequiyalencc relevant to their new molecular environments.

Further investigation of tliis "chemical shift interchange"

effect due-to solvation is•attempted in-the present Vork through

t-he-s\Tithe?e?^and;^ exchange of two con-

formationally restricted sulfoxides, namely thioxanthene-10-oxide

and 9-thia-:),10-dihydrophenanthrcne-9-oxidc (see Figure XIXJ.

FIGURE XIX CWFORMATIONAI-LY ÏŒSTRICTKn ffln.mYTpco

tdiioxaritdiene - 1 0 -oxide

Ci EVITER 6

EXIGER rLNTAL

181

6 - 1 . INSTRlMyNTAlTON

-NuL.4-ear-magnet-i-e^

Varian A-60 and IL\-10g instruments at 60 MHz and 100 MHz respec­

tively, with probe temperatures ca_. 40°C unless otheivise-speci­

fied. Clvemical shifts are reported on•the r.scale, i.e., relative

to the intentai • standard signal of totramethvls'iL'inc. Infrared

(i.r. ) spectra were/recorded on Perkin-hlmer 23/B or 225 spectro­

meters, .bach i.r. spectnmi was calibrated against a portion of

a polystvrene spectrum. An Hitachi/Pcrkin-blmer IJMlMih mass

spectrometer recorded the mass spectra (m.s.) at an ionization

voltage of 70 ev. Gas-liquid chromatographic (R.I.e.) analyses•

,were carried out on a Beckjnan GC-2A instrument with a Carbowax-

-1OO0 dioleate column (2.5 ft) at 190°C with "20 lb per in7 pres­

sure of hclium_carri,e.r_gas.. Meltrng-points-(m.p.d-wc re-determined-

on a' Fisher-dohns melting point apparatus. Melting points and"

boiling noints (.b.p.) ai'e uncorrected'. (Theniical microanalvses

were carried out by the Alfred Bernhardt yrtkroanalytisches babor-

atoi'iimfy-best Gennanv.

v*

6-2. MATERIALS

o-Nitrobenzyl phenyl - sulfide. - - Sodium (17;2yg; 0.747 mole)"

0.8110 mole) was added dropwj.se to the reflibcing solution. After vthe complete evolution of hvdrogen, the solution was allowed to • cool slightly below the reflux temperature, and a mixture* oi o-and p-nitrobenzyl chlorides (125. g ; '0.'29 mole; technical grade! rn anhydrous xylene (400 ml) was added dropwise over 1 h. Sifter, the exothermic reaction was complete, the hot Solution was fil­tered immediately. - ' . - • - •

The residue was washed with diethyl ether (100 ml], and sol­vents were removed from the respective filtrates bv distillation under reduced pressure. 1 he-reddish-brown residues were combined

and~t akerr up"in~hot-abs olnt e~e tlrarfdTT Oh~TôT5TiT5Tf ^ " (152.1 g; 85.27 yield) of o- and p-nitrobenzyl phenyl sulfides crystallized. The product was rccrystallized four times from ab-solute ethanol, m.p. 64-65°C [lit, m.p. 64°C (167)] [Found: C,

*The mixture of nitrobenzyl chlorides was supplied by Aldrich

Chemicals as teclrnical grade o-nitrobenzvl chloride. Later anal-

yscs (n.m.r. and g.l.c.) indicated the mixture \fds 655 ornitro­

uas drspersed in anhvdrous xylene (500 ml) , and thiophenol ( SS g:;

requires C, 63. ,67^0, 4.52; N'y. 5.71;. 0, 13.05; S, 13.055].-

"benzyl chloride and 355 p-nitrobenzyl chloride.

.183

An n.m.r. spectrum (CC1 U) had three absorptions, a singlet

at—5-rfrl --(-ffl to 1.90 T (protons attached to aromatic rings). The integration

of the singlet to that of the multiplets'was in the ratio.of 2:9.

An i.r. spectrum (CCTM) showed absorptions at 3060-Xçm"1 (medium)

for the aromatic Q1 stretch, 2930 cur1 and 2855 cm"1 (small)'for

the Ql 2-S asymmetric and svmmetric -stretches, 1520 an"1 and 1550

cm"1 (strong) for tire-asymmetric and symmetric aromatic N 0 2

stretches, 1435 cm"1 (medium) for the CH2 deformation,- and 1090

cm"1 (small) for the aryl-S stretch. A mass'spectrum showed the

molecular ion at an m/e value of 245.

o-Aminobenzyl phenyl sulfide. - A mixture of o- and p-nitro­

benzyl phenyl sulfides (28.8 g; 0.117 mole) dissolved- in methanol

(2000 ml) was added to,Pd/C (55; 9.8 g) and H 20 ('inn ml). Hydra­

zine (85%; 300 ml) was cautiously added to the solution and the.

mixture was re fluxed for 36 h. The hot solution was filtered,

through Celite, and the- solvent .removed by distillation under -

reduced pressure. The residue was dissolved in hot ligroin '(b.p.

100-115°C) and white prisms (21.8 g; 86.8%'yield).of o- and p-

-aminobenzyl phenyl sulfides formed on' cooling, m.p. 80-82°C

[lit. m.p. 81°C ( 1 6 7 ) ] [-Found: C, 72.57; II, 6.08; N , 6.38; S,

14.95. C13H13NS requires 67, 72.54; H, 6.09; N , 6.51; S, 14.865].

The product was recrystallized three times from ligroin (b.p..

100-115°C). ' - - < ; -

184

""x An n.m.r. spectrum (CC14) showed three absorptions, a broad

singlet at 6.30 - 5.99 T ÇNH2) , a singlet at 6.00xr_f,ŒbJ and-a*

multiplet from 3 .60 to 2 .61 T jiving two major peaks at 2 .79 T-

and 2.77.x (protons • attached to'the aromatic ; rings). Tire ratio

of the respective integrations was-2:2:9. .An i.r. spectrum (CC1M)

showed absorptions at 5440 cm- 1 and 3545 cur1 (medium) for the

asymmetric and symmetric fdH2 stretches f 3060 cm'1 and 5020 cmL 1

(medium)rxfor the aromatic CH stretch, 2950 cm"1 with a shoulder

at 2920 orf1 (small) for the C lh -S stretch, gH520 cm"1 (strong) . ; y

for the N!!2 deformation, 1495 cm"1 and 14S0 cm""1 (medium) for the-

• b deformation and wag and 1090- cm"1 (medium) for the aryl-S

stretch. A'nuiss spectrum showed the molecular ion haTl an m/e

value of 215. -

__9z.Thia-9-, 10-dihydrophenanthrene : —'the~Ps"chorr Reaction. '•'"•--'

(i).A mixture of o- and p-aminohenzyl phenyl sulfides ( 8 . 6 g;

0 .040 mole), dissolved in HC1 (5M; 300 ml) was cooled to -5°C.

Solid sodium nitrite (25.0 g; 0 .0435 mole) was' slowly added.with

stirring over 0 . 2 5 h, and the resulting diazonium salt, was stir­

red for 0 . 5 h after'the, addition." Copper powder ( 5 . 0 "g; 0 .047

mole) was slowly yidded to the cold solution. . ,-• ' ~ • • v -

The gas which evolved (983 ml) was collected over .water and

its volume-exceeded .the theoretical amount"' of^ktrogen by "24 ml."

This excess was tentatively attributed to nitrogen dioxide,'''the . • S " . ' . -v -..

reddisli-brov.n color and pungent odor of-which were readily detect­

ed. , The solution was allowed to come to .roomy-temperature with **

stirring over IS h, an 1:1 finally warmed to ca. '40°C until the evolution of gas was complete 10.5 If).

Diethyl ether (100 ml) was added to tlie cooled solution and - . • . i.i i " • •• 1 1 1

the mixture was filtered through Celite. Tflie residue was washed with water (100 ml) and two nortipns of diethyl ether (50 ml)-. -The layers fcre separated and the aqueous layer was washed with. three portions of diethyl ether. (150 ml). The combined ethereal extracts were dried oyer anhydrous magnesium sulfate, and the solvent iyas removed by distillation under reduced pressure.'1

'i ' The(residue- was extracted with petroleum ether (b.p. 50 -

o -60 C) and the extract was placed on a neutral alumina column X 1 - ' ' , o • (300 g) developed by petroleum ether (b.p. 30 - 60 C). After an

^ j initial 300 ml of cluent, a light yellow oil began to issue from' the column. Elation with a further 400 ml of solvent appeared

i ' • • to completely wash the oil from the column. Attempts to crystal­lize (QlyOin or sublime the oily residue (5.30 g) .after solvent

i • ' "' evaporation failed to separate the products.,

A mass spectrum of the material showed at least three mole­cular ions at m/c values of 198, 200 and 234. A g.l.c. analysis showed five separate peaks (see Table XLIX) . A sample of the residue on a thin-layer chromatographic plate developed with petroleum ether (b.p. 50 60°C) showed five spots, confirming the 'g.l.c. analysis.

186

T A B L E X I , I X

. A CAS-LTQUin •IROMATOGRAPTflG ANALYSIS* OE-T1E dlRÇ^^

THE PSaiORR REACTION.

PEAK NUMBER • RETENTION TIME ( M I N ) STRIJCTIJRE A S S I G N E D 2 OE M I X T U R E

8.6 CcH5f-ai2-S-C5Hb v 27.2

14.1 • -• . CG I IS - S - S - CCUG I.O

17.1 o-Cl-CelE-aU - S - C G I E 18.9

21.4 ' . p-Cl-C6lU-a-l2-S-CF,II5 12.S

27.2 . unidentified** 39.2

-The column'used was a 2. S Et _Carbowax '4000-dioleate colimm at

1 9 0 ° C with a helium carrier gas flow of 1.25 ml/sec.

**This. was identified as 9-tlvia -9 ,10-dihydrophenanthrene below.

The residue was distilled under .reduced pressure (0.05 - •

0.05 mm llg) and four fractions were collected. A g.l.c. analysis"-\

of'thc first fraction (96*- 1 (>3°CTj showed the major component had _ .—- ••' • i ' --— 1—• • " 1 "•

a retention- time of 8. (v m in. '"Th'c "fraction 'was' takenTfp in hot methanol and on cooling (-5°C) crystals of benzyl .phenyl sulfide were isolated, in.p. 59 - 40PC ["lit. m.p. 39 r -10°C .(108)] [bound: C, 57.94; II, 0.05; S, 10.05. C, ,Hi2S requires C, 77.9-1^ II, ' 6.04 ;

• S, lu.na0, 1. lire g.l.c. retention time ol recrvsta 11 i zed honzvl • : At ''

phenyl sulfide was 8.0 inin,-and this coincided with the retention time of an authentic sample of benzyl plienyl sulfide.

An n.m.r'. spectnim (CCI., ) showed two absorptions, a singlet at 5.99 r (fib) and a multiplet from 5.00 -[ to l.(i7 i , the major peak appearing at 2.80 T (protons attached to the aromatic rings). The ratio of the respective integrations was 3:10. An i.r. spec-frum (CC1,,> showed absorptions at 3055 cm'1 and 5030-cm"1 (strong)

~~~"[ol^he^lFnTro 2910 an"1 (medium) for the CJL-S stretch, 1589 an"1 and lhOS on"1 (strong) for the monosubstituted benzene ring stretches, a scries at 1498 cm"', 1485 cut"1 , 1458 air1 and '1445 an"1- (all strong) for the various Qb deformations and wags, 1095 cm"1 and 107 o cm 1 (both modi inn) for the arvl-S stretclK A mass spectrum showed .'the molecular ion at an m/e value of 200.

The second fraction (110 - 113°C) was analyzed by p.I.e. and the major peal had a retention time of••17). 1 min. The fraction

188

was a mixture of benzyl phenyl sulfide (16.1?,) , oichlorobenzyl phenyl sulfide (62.62) *, and p-chlorobenzyl phenyl sulfide (21,3C,):

This analysis was confirmed byan n.m.r. spectrum (neat) which •had four absorptions, three singlets at 6.52 T (CH2 of p-chloro­benzyl phenyl sulfide), 6.41 x (Cfb of benzyl phenyl sulfide) and 6.27 T (Qh of o-chlorobenzyl phenyl sulfide) , and a multiplet from- 3.62 T to 2.96 T (protons attached to the various' aromatic rings). The ratio of the respective methylene integrations indi-'cated that the mixture was 62.52 o-chlorob en zyl phenyl sulfide-, 15.92 benzyl phenyl sulfide, and 21.62 p-chlorobenzyl phenyl sul­fide. The assignments of the latter two methylene singlets were confirmed by the corresponding rise in intensity of the respec­tive signals with the addition of authentic samples of each to the mixture.

An i.r. spectrum (CCI,2) of the mixture had absorptions at • 3050 cm"1

1 (medium) for-the aromatic CH stretches, '2920 cm"1 (weak) for the Cl l2 - S stretches, 1580 an"1 (medium) for the aromatic ring stretches, 1478 cm"1 (medium) and 14S7vbzm"' $il Lium) for the Qt2

deformations, 1090 an"1 (medium) for the aryl-S stretches, 740 an"1 (medium)"and 690 cm"1 (medium) for the C-Cl stretches

•y y

-This is a tentative structural assignment [lit. b.p. 114°C at 0.05 mm Hg (169)]. ' ^ **This is a tentative structural assignment ; proven correct below. ' • <j

189

[Found: C, 68.4; H, 5.0; Cl, 11.6; S; 15.3. The mixture, if correctly determined, requires C, 68._3; I I , 4.9; Cl, 11.5; S, 15.35]. ' , ' '. « :

—. Ijra_thii:d^-r-uGkioiw(d^^^ ,

and on coolittg, v.hi te'prisms of p-chlorobenzyl phenyl sulfide crystallized, .m.p. 77.5 ;-. 78.5°C [lit. in. p. 77.5 - 78°C (169)1 [Found: C, 66.68; II, 4 .86 ; CI, 15. 03; .5, 15.51. C, 3H, , CI 67 requi res C, 66.50; I I , 4.73; (71, 15.11;-S, 13.66°01. ^

A g. 1. c. , analvs i s showed a single peak at a .retention time of.21.4 nun. A mass:spectrum^showed a molecular ion at an m/.e

value of 234. An n.m.r. spectrum (CClf) had three 'absorptions, a singlet at 6.00 i (Ob) mid two smgJets at 2.80 T and 2.79 r

•i - v

(protons attached to aromatic rings'). The ratio of the integra­tions was 2:9, the integrations of the latter two absorptions being combined. An i.r. spectrum (CHC13) showed .absorptions at 5060 cnC 1 ( cdiium fgy (medium.) and 2920 enc,1 (small) for.the OI2-S stretches, 1585 cm"1

with a shoulder at 1595 an"1 (medium) for the aromatic ring stretches, 1480 cm"1 (strong) for the CHZ deformation, and 1093. an"'1 (strong) for the arvl-sV stretch.

Tlie fourth .fraction (121 - 125°C) was examined by g.l.c. and. showed only two major^peaks at retention times of 21.4 m in and-; 27.2' min. The former corresponded to that of p-chlorobenzyl phenyl sulfide. The components of this fraction could not be separated. " ^ ) .., '

190

• ••A g. I.e. analysis showed that the retention time (14.1 min) of an authentic sample of diphenyl disulfide, when compared with .the retention times of the components of the dhschorr reaction 'mixture, corresponded. with that of peak number 2, Table XLIX..

An ir.m.r. spectnim (CCT,) of the complete 1'schorr reaction mixture indicated.the unidentified compound (g.l.c. retention' time 27.2 mini had eight aromatic protons. .This datum was dc--duccd hy identification of the other'r ornponents and their sub-

' J .-7,1'

. traction from the spectrum, whiles assuming the contribution of diphj^vf^disulf ide was negligible;. \

A Sandmeycr reaction (170) was carried out using the mixture of o- and p-aminobenzyl 'phenylsulfides. \Botlr o-' and p-chloro-benzyl phenyl sulfides were isolated,.and-their respective reten-

• \ • " ' a' tion times (17.1 min and 21,4 mm) corresponded to the retention • • -r / ' .

times assigned_ to o- and p-chlorobenzyl phenyl sulfides produced in the Pschorr reaction. A

(ii) A mixture of o- and p-aminobenzyl phenyl sulfides (7.1 g; 0.035 mole) was added to acetone (lfJOO ml) and sulfuric acid • (cone; 18 ml). The resulting hydrogen sulfates -were diazotized-/'at 0°C by the-addition of isopentyl nitrite'(9 ml). Sol id,.-sodium iodide (20 g; 0.133 mole) was added to the cold solution, and ,a gas'was spontaneously evolved. The solution was warmed-to 80°C and poured into' hot water-, whereupon an oily organic layer'sep­arated but did not crystallize (171)..

191

Hie free iodine was taken up with sodium thiosulfate (6N;

50 ml) and the solution was washed with diethyl ether (150 ml).

The ethereal extract was dried over anhydrous magnesium sulfate,

and-t-he-scrlvcntsn s~Tlîen removed "bv-dis t i 11 at i on under reduced'

pressure. The residue was taken up in hot metbuinol and on coolin

white prisms of p-iodobenzyl phenyl sulfide formed (2.1 g; 19.55:

yield). The product was recrystallized (ClIyTH) and sublimed, • •

m.p. S .5 -8S.5°C [lit..m.p. 88°C (172)1 [Found: C, 47.85.; H, •

3.50; I, 38.85; S, 9.90. Ç i 3II MIS requires, C, 47.85; II, 3.40;'

I , 38.92; S, 9.8.35].

<? A mass spectrum of the product showed a molecular ion at an

m/e value of 526. An n.m.r. spectrum (CCI,,) had four absorptions

a single! at 6.04 T (Oh), a doublet at 5.03 T 'coupled to a doub­

let at 2.45 T (A2B.: system for protons attached to benzyl ic aryl

•ring; J,\?.Br = "") , and a singlet at. 2.SO T (protons attached

_toJdjc_ plienyl,_r.ing) Thc-respective-integrations'-we7fê"~iiT hi?" ~~

ratio of 2:2:2:5. An i.r. spectrum (CCI4) had absorptions at

5065 cm"1 and 3010 cm"1 (both medium) for 'the aromatic. Ql stret­

ches, 2915 cm'1' (weak) for the Clb-S stretch, 1588 cm"1 (medium)

for .the aromatic ring stretches, 1490çcm"1 and 1445 an",1 (both

strong) for the Ql? deformations, 1095 an"1 (medium) for the

aryl-S stretch, and 1065 cm"1 (strong) for the aryl-I stretch.1

(iii) A mixture of o- and p-aminobenzyl phenyl sulfides

(21.5 g; 0.100 mole) in sulfuric acid (5M; 200 ml) and ethanol

(957; 400 ml) at 0°C was diazotized bv the addition of solid

191

sodium nitrite (7.1 g; 0.105 mole). The solution was stirred for 1 h at 0°C and then copper powder (10.0 g; 0.158 mole) was slowly added.- The solution was allowed to come to toom temperature with .tir.id.ng-ovej~20-h-.—~The-volume o . reacfipn was 2530 ml, slightly exceeding the theoretical amount of nitro­gen possible. ,

The solution was refluxed for an additional 0.2 h on a steam bath. After cooling, diethyl ether (300ml) was added, and the s o l u t i o n n a s filtered through Celite. The filtrate was separated and the aqueous laver was washed.with three portions of -diethyl ether. (300 ml total). The combined ethereal extracts, were dried over anhydrous magnesium sulphate, and the solvent was then re­moved bv distillation under reduced pressure. The'residue was extracted with^petroleum ether (b.p. 30 - 60°C) and the solvent removed in similar fashion to the latter.' *

A. S^lms^of ytjie jyeasd. atc2202C-and_the-f-1 o w — of helium carrier gas at 0.714 ml/sec)'-showed two peaks'at reten­tion times of 2.05 min and 6.0 min. The compound ascribed to the former was benzyl pRenyl sulfide, -and under new conditions (temp­erature at 190°C and the flow if helium carrier gas at 1.25 ml/ sec) the retention time -of the latter was-27.2 min, corresponding to that of the unidentified compound from the dilute HCl-Pschorr reaction (see Table XLI

\

The residue was distilled under reduced pressure (0.05 -

0.03 mm Hg), and two fractions were collected. The first frac­

tion (2.8 g] 14.0°5 yield) collected at 104 - 106°C gave a single

ized twice (QfOIl) , m.p. 38 - 40°C, and its n.m.r., i.r., and

mass spectra "were similar in all respects to an authentic sample

of benzyl phenyl sulfide. The second fraction (2.6 g;-15.12'

yield) collected at 122. - 124°C was identified as 9-thia-9,10-'

-dihydrophenanthrene and it had a single g.l.c. peak at a reten­

tion time of 27.2 min. It was recrystallized twice (CH30H) and

sublimed, m.p, 75.5 - 76.0°C [lit. m.p. 75.5°C (167)] [Found:

67, 78.70; .11, 5.21; S, 16.05. C 1 3 H 1 0 S requires C,,78.75'; II, 5.09;

S, 16.18%'].

. A mass spectrum of the compound had a molecular ion at an

m/e value of 198. An n.m.r. spectrum (CCT,) showed two absorp-

.tions a - 5 i ng le t-at-6 .29-T— (CF[2-)-and-a--mUlt-iplet-from-2-.-99-t-to—

2(20 T (p/otons attaclied to the aromatic rings). The respective

integrations were in the ratio of.2:8. An i.r. spectrum (Q ICI 3)

had'absorptions- at 5045 enf 1 (medium) for the aromatic CJI stret­

ches, 2890 air 1 and '2800 air1 (both weak) for the (2H2-S stretch,

1587 cm - 1 (medium) for the aromatic ring stretches, a series of

(strong) peaks at 1485 on"1 , 1468 cm"1, 1445 cm"1 and 1422 an"'1

for the QI2 deformations, and 1075 cm"1 (medium) for the arvl-S

stretch. . 0

. •:' ' ' 194'

9-Thia-9,10-dihydrophenanthrene-9-oxide. - (i) 9-Thia-9,

10-dihydrophenanthrenc (2.62 g; 0.0132 mole) dissolved in glacial

acetic acid (50 ml) and methylene chloride (50 ml) was cooled to

• 5°657~and—50 %~nydrogen-^eroxide^ •

dropwise to the stirred solution. The reaction mixture was al­

lowed to come to room temperature over 4,8 h. The" methylene chlo­

ride was removed by distillation under reduced pressure and the

solution was; lyophilized. The residue was taken up in hot ben­

zene-hexane (1:4) and on cooling white prisms of 9-thia-9fl0-di-

hydrophenanthrcne-9-oxide (1.61 g; 57.1" yield) precipitated

from the solution. The material was recrystallized three times

from benzene-hexane (1:4) and washed with petroleum ether (b.p.

50 - 60OC) , m.p. 101 -' 102°C [Found: C, 72.85; If, 4.72; 0, 7.47;

S,. 14.92. C13II10OS requires C, 72.87; H, 4.70; 0, 7.47; S,

14.967)].

_ L A_)iiass_.spectrun_of_tlie_compouiid_liad._a molecular_ion_at_aii

m/e value of 214. -An n.m.r. spectrum (CD3CDCTJ3) showed two doub­

lets of an AT quartet at 5.79 T and 5.51 T (nonequivalent methyl-

ene protons; = 14'.0 Hz) and a multiplet from 2.72 T to 1.90 T

(protons attached to aromatic rings).

(ii) 9-lhia-9,10-dihydrophenanthrene (1.98 g; 0.0100 mole)

in methanol (200 ml) was added to sodium metaperiodate (2.14 g;

0.0100 mole) dissolved in methanol (2500 ml) at 0°C and the

solution was stirred at this temperature for 5 days.

I 1 9 5

The solid material was subsequently removed by filtration

and washed-with, diethyl ether (ZOO ml). The solvent was removed

from the filtrate by distillation under reduced pressure and the

rj sjxlue-w'as ta

combined ethereal solutions were dried over anhydrous magnesium

sulfate, and the solvent removed by distillation under, reduced

pressure. . •

The residue dissolved in'benzene, (2 ml) was placed on a sil­

ica gel G (47.8 g) • chromatography column which.was developed by

the eluents detailed in TABLE L. ' Each fraction .collected [50 ml)

was examined subsequent to solvent removal by distillation.under

reduced pressure. The residue of the combined chloroform .frac­

tions was taken up in hot benzene-hexane (1:4)' and on cooling

white prisms of 9-thia-9,10-dihydrophenanthrene-9-oxide (1.42 g;

50.47 yield) precipitated, m.p. 101 - 102°C [Pound: C, 72.75;

1 1 ' 4 _ l S 0 . ; •°> 1 • 5 7 ; Li'^JArJliY 0, 7.47; S, 14.967]. The n.m.r. (CD3œCD3) and mass spectra of

the material were similar in #11 respects to those-of 9-thia-9,

l0-diliydrophenanthrene-9-oxide prepared above'. y 7/

Tliioxanthene-10-oxide. - Thioxanthene (25.0 g; 0.126 mole;

Aldrich Chemicals) dissolved in chloroform (20 ml) was placed on

a silica gel G (500 g) chromatography cofTLirnn developed by petrol­

eum ether (b.p. 50 - 60°C; 4000 ml). The petroleum ether was

removed from the collected fractions by distillation under reduced

TABLE L

THF. ELUT ION OF THE 9 -TmA-9 ,10-DiE?iDR6^ AND SODIUM METAPERIODATE

FRACTION NUMBER

1 - 6

•7 10

11 - 12

13 - .15

16 - 20

21 - 24

25 - 27

28 - 50

31 - 80

REACTION MI COURE ' ON A SILICA GEL "G (2JTORTOGRAPHIC COLliï-N

ELUENT COMPOSITION

petroleum ether (h.p. 50 - 60°C)

benzene-petroleum.ether (1 :9J

benzene-petroleum ether-(1:5)

benzene-petroleum ether (1:1)

benzene

benzene-chloroform (3:1)

J benzene-chloroform (1:1)

1 benzene-chloroform (l.:3)

chloroform

VOLlJM: OF ELUENT (ml)

300

200

100

150

250

200-

150

•150

2500

pressure, and the residue was recrystallized three times from

chloroform-ethanol (T:5) . The resulting white needles of thiox­

anthëne ' (23.1 g; 92.41 yield) were collected and air dried, m.p.

150 - 131°C [lit, m.p. 128 - 15d°C (173)1 [Found: C, ,.7S...7.a:^]J..^

5.12; S' 16.03. C j 3 I I 2 o S requires C, 78.75;'!!, 5.08; S, 16.17%]. •

• Purified thioxanthëne (14.37 g; 0.0725 mole) dissolved in

glacial acetic acid (100 ml) and methylene .chloride (200 ml) was

cooled to -5°C, and 501 hydrogen peroxide • (8.21 g ; 0.0725 mole)

was added dropwisc to the solution. The reaction mixture was

gradually allowed to come to room temperature with stirring over

48 h and the solvents were subsequently removed by lyophilization.

The residue was taken up in boiling hexane and white .crystals

(13.86 g) • precipitated from the cold solution. .An n.m.r. spectrum

(CT0 3) jaidicated that this material was a mixture of .52 thiox-.'

anthene (GI2 at 6.17 T), 922 thioxanthëne-10-oxide (two :AB doub- ;

lets at 6.25 T and' 5.85 r; d^ = 16.8 Hz) and '3% 'thioxanthëne-10

10-dioxide (CH2 at- 5 .78 T ) . \ f.

The mixture (5.21 g) dissolved in chloroform ( 2 ml) was

placed on a dry neutral alumina (Fluka; 500 g)•"chromatography " > ' *

column. The column was initially eluted with petroleum ether

(b.p. 50 - 60°C; 4100 ml), and.each fraction (100 ml) was collec­

ted and weighed subsequent to sol\rent removal. The weights of

the material from the initial 20 fractions did not increase or

decrease appreciably with .fraction.numbers, but remained between

198

0.145 g and 0.120 g for'each fraction. The total weight of the

material recovered from these fractions was 2.65 g, 'representing /

•slightly more than 50% of the material placed on the column. .The — material was -recrystallized from-chloroform-ethanol (1:3) and

; •

identified as thioxanthene, m.p. 130.3 - 151.0°C [lit. m.p^s128 -. • '

131°C (173)]. An'ur.m.r. spectrum (CD3COCD'3) and amass spectrum ' ' ' ! were similar in all'respects to those of purified thioxanthene •

,7 . " i ' • • • ' • prepared above. ; " ' V i j * Material (0.160 g; 35 of reaction mixture) recovered-from

subsequent elutiori of the column with benzene-petroleum ether

(1:1; 2000 ml) and neat benzene (1000 ml) was recrystallized from

ethanol. It was identified as thioxanthene-10,10-dioxide, m.p.

^173.5 - 174.5°C [lit. m".p. 174 - 175°C (175)]'.

The column was'then eluted with benzene-chloroform (1:1;

2000 ml), heat chloroform (2000 ml) and chloroform-diethyl ether

(9:T-;-2000-mT)-Y --The-TMATERIAL"(-2r38-g;--45T6%-of-reaction-mixture) —

recovered from ..the final eluent was recrystallized three times

from chloroform and was identified as thioxanthone, m.p. 213 -

.214°C [lit. m.p. 215 - 214°C (173)] [Found: C, 73.52; 11, 3.82;

0, 7.52; S, 15.05. Ci 3H 0OS requires C, 73.56; Fl, 3.80; 0, 7.54;

S, 15.107]- A'mass spectrum of the compound showed a molecular

ion at an m/e-value of 212, and an n.m.r. spectrum,(CTJ3CJOCD3) indi­

cated only the presence of.protons attached to aromatic rings,

This chromatography procedure was repeated using inaterjcfl

1 9 9

(5.52 g) from the initial reaction mixture and similar results were obtained, i.e. 532 thioxanthëne, 41, thioxanthëne-10,10-diox­ide and 41" thioxanthone. In both experiments, thioxanthene-10-

... .-oxide coula not he recovered. - . — -.. t.. - • - • - -i The remaining material (.3.13 g) from the.-rcaction mixture was recrystal-1ized,three times from hexane. The resulting white crystals of thioxanthene-10-oxide, m.p. 117 - 118°C [lit. rn.p. 116 - 117°C (.174)], -were then sublimed (90°6; 1 mm ilg) and re-crystallized from hexane, m.p. 110,- lll°£jyiit. m.p. 109 - 110°0 ; •(175)].'

The reaction procedure was repeated using purified thioxan­thëne (5.22 g; 0.0264 mole) and 301 hydrogen-peroxide (2.95 g; 0.0264 mole). Following lyophilization, thioxanthëne-10-oxide ' -'(4.75 g; 842 yield) was isolated by recrystallization (Cell!,,) and sublimation, m.p. 110 - 111°C [lit. m.p. 109 - 110°C (175)]

—-[-Found t—C-T-"7-27-79 ;-H7"4-75';-0_—7-38R S~14T95T— CnHrsOS-requires—-— C, 72.87; I I , 4.70; 0, 7.47; S, 14.96au]. Amass spectrum of the

N compound indicated a molecular Ton at an m/e value of 214, and an n.m.r. spectrum (CDC13) of the compound showed two. doublets of an AB quartet at 6.23 T and 5.85 r (nonequivalent protons of Chb ; J.yp = 16.8 Hz), and two multiplets, 2.67 x to 2.48 r and-2.18 T to 1.83 r (protons attached to aromatic rings).

The reaction procedure was repeated a third time using.puri­fied thioxanthëne (1.98 g; 0.0100 mole) and 302 hydrogen peroxide

200

.[1.13 g; 0.0100 mole)2 Following lyophilization, the reaction I •

.mixture dissolved in chloroform (2 ml) was placed on a silica gel G (200 g) chromatography column developed with petroleum ether, (b ,p... 30- - 60°C) 9- Material- recovered' from"' the petroleum ether fraction (300 ml).was identified as thioxanthene,-and sub-

sequent elution of the colimin with benzene y500 ml) led to the isolation of thioxanthene-10,10-dioxide. The column was then eluted with chloroform-benzene (1:1) and finally neat chloroform. Thioxanthene-1.0-oxide, representing 81% of the reaction mixture,

N < — . vans isolated fi'om tlie conjoined chloroform iractions.

Proton-deuteron exchange at the'cyclic methylene of 9-thia-- 96, 10- d ihydjophenanthrene - 9 - oxide. .- 9-Thia-9 ,10-dihydrophenan-threnc-9-oxide (0.350 g; 2.57 x.1.0"3' mole) dissolved in acctone-

i i

-dç ("5.85 g; 6.02 x 10"2 mole), deuterium oxide (0.275 g; 1.58' x 10 'yniolc) and triethylamine (0.550 g ; 5.45 x 10 3 mcde)_was allowed to stand at room temperature for cja. 0.5 h. . The solution cy-i

'was then lyophilized and the residue was recrystallized twice from benzene-hexane (1:4), m.p. 101 - 102PC.

I . • Proton-deuteron exchange at the cyclic methylene of thioxan­

thene- 10-oxide. - (i) Thioxanthene-10-oxide (0.750 g; 5.50 x ' P"r 3 mole) dissolved in acetone-d6 (2.45 g; 5.83K 10"2 mole), deuterium oxide (0.375 g; 1.88 x 10 " mole) and triethylamine (0,750 g; 7.45 x 10"3 mole) was allowed to stand at room tempera­ture for ca_. 5 min. The solution'was subsequently lyophilized

}

and the residue v/as recrystallized twice from hexane, m.p. 117 -118°C [lit. m.p.Ulô - 117°C (174)].

•(ii) To thioxanthene-10-oxide (0.050 g ; 2.54 xJO'1' mole); ; a drop of aqueous sodium hydroxide (6N) was added. Within 10 min at ca. 40°C'the methylene protons could not he detected in an' n.m.r. 'spectrum. The yellow solution began to turn blue within 15 min after the addition of base, but reverted.to a.clear yel­low color upon-shaking. • Tire recurrence of the blue color1 per-'' sisted for several hours after several repetitions of the shaking pyrocedure.

'QLAPTER 7 RESULTS /END DISCUSSION

7-1." 9-THIA-9 ,lO-DIffîmOPHI^AN'niPTim-g-OXIDE

The synthetic route to 9-thia-9 ,l0-dihydrophenanthrene-9-—ox-i de— (-TDP0 ) -r-i-1-1 u s t-r-at ed-by—Figure—XX-y-hasyjeen-par-t-ial-ly—Iji-vestigated by Liittringhaus and Ko lb (167.) in 'their -study of 9-thià-phenanthrenium-pèrchloraie. .Although the present synthes­is of TDPO followed a similar route, the yields.of Intermediate

^products and the properties of these' products were not always in agreement with those described by Luttringhaus and Ko lap. The vfntegrity of thev 9-thia-9,10-dihydrophenanthrene (TDP) prepared in 'the present study has also been verified by Dewer, Forrester arid Thomson (175), who have' concurrently synthesized TDP in an

'alternate manner but describe a similar melting point. • • Although Rabldeau, Harvey, and'Stothers (176) have calculated

the free energy barriers, for conformational interconversions of various 9,10-dihydrophennnthrene derivatives, no such barrier was observed in the case of TDPO. N.m.r. spectra (CS2 ; CD3SOCTJ3).. at temperatures ranging from -85°C to 100°C did not indicate any coalescence of the .AB quartet nor the appearance of another dupli­cate quartet. Although the possibility of a large free energy barrier to conformational interconversion may exist such that solvated-TDP occurs only in one preferred form, rapid intercon­version 'between, the two stable conformers (177, 178) probably represents a more correct interpretation of n.m.r. spectral temp­erature independence (see Figure XXI) .

203

FIGURE XX A S W I H m C ROUTE TO

, 9-lrHA-9;iO-DIHYDRÛPHEN^^

CH2CI (-)(+) S No

+ LOI "N0 2

o-nitrobenzyl sodium chloride thiophenoxide

anhydrous xylene reflux

( + ) • (1) H30 /NaN02

(2) Cu powder •5°C

9-thia-9,10-dihydrophenanthrene

-5°C

o-nitrobenzyl phenyl sulfide

hydrazine (85%) Pd/C (5%) reflux

methanol/water

'CHo — S

"NH 2

o-a7iririobenzyl phenyl

sulfide hydrogen peroxide (301) glacial acetic acid/methylene chloride

9 - tJii a - 9,10 - dihydrophenanthrene - 9 - oxide

I FIGURE XXI )

IMTMHNVERSION OF THE TWO STABLE COOTORMEES OF 9rTHU-9qO-DIHYDRQPHENANmRENE

j 1

I i

N.m.r. spectra of TDPO which lias undergone partial hydrogen--deuterium exchange at the cyclic methylene position indicate ' ' that the "methylene proton represented by the upfield doublet of

'-th--*\:'""Y:'':,''t'-'d-":c- I~c :.].<-• in basic media-than the proton - -

represented by the dov.nfield doublet, ft is equally evident that the chemical' shifts of 11 and 11 , the methylene protons, do not interchange positions v.'hen the. partially deuterated TPPO is dis­solved in trifluoroacetic acid with respect to- their chemical

.shifts in dimetliyl sulloxide-df, (see Figures XXII and XXIII). This is implied by the n.in.r.. spectral shift of the "slow-exchange" proton, labelled by the downfield unresolved -CUD- triplet repre­senting one of the two diastereoisomeric forms, which remains downfield in both trifluoroacetic acid and dimethyl sulfoxide-d6,

'i.e., the two AB doublets of the-quartet do not interchange n.m.r. spectral ppsitions with respect to each other when 1T3P0 is sol-

.vated-respect-ively-by-trifluoroa

'. -.- -• . - •. - •• X - • •• • • • . 206

FIGURE XXII PORTIONS OF N . M . R . SPECTRA OF PARTIALLY DEIjTERATEI)

TDPO DISSOLVED IN TRIRUORÛACTTIC A C I D

6-OT (a) the unresolved -CHD- triplet of one of the

TDPO diastereoisomers generated in the proton--deuteron exchange reactions at the methylene position

.1 ,_J- 1 I JL 5 0 1 5-5T 6 OT

(b) the spectrum shown in (a) with the AB quartet resulting from added protium TDPO

J FIGURE XXIII PORTIONS OF N.lf.R. SPECTRA OF PARTIALLY IMJITdRATED

! TDPO DISSOLVED IN DIMETHYL SULFOXIDE-d6

(a) the unresolVed -CHD- triplet of one of the TEPO diastereoisomers generated in the proton-

• | . \ -deuteron exchange reactions at the methylene

5 0 (b) the spectrum shown in the AB quartet resulting from adçîed protium TDPO

!08

7-2. THIOXAN'HU-MMO-OXini- .

Mr Thioxanthenc-10-oxide (TXO) was prcpXlnred by the simple oxid-

-:>. r-i'>n-n*—thT^xnnth^T.r-X^"~!• : .-ai e .'Oa Vj"! 1 ;:o reaction of-TXO in

aptotic solvent media ('petroleum ether, benzene, chloroform, di-

cthylyetner) on a neutral alumina coltrnm appears to be a novel

disproportionation in which, the TXO is converted to thloxanthonc

and thioxanthoiie (.see figure XXV). Although the oxidation of

the methylene group to the corresponding alcohol may occur via

an intramolecular mechanism due to intramolecular hydrogen bond­

ing, the fact that tbioxarithenc and thioxanthone are probably ,

produced in equal proportions suggests that the second oxidation

step occurs via an intormolecular mechanism.

In a study of TXO and numerous derivatives, Tcrnay and co­

workers (179, 180, 181, 182, T85) argue that the polymorphism

.exhibiteddry-two-di f fc rcnt-mclt-ing-spec-ies-of--TXO~(T 73)—which

appear to have different infrared spectra in the SO stretching

region (173, 183), corresponds to the two stable coniormational

fonns of '1X0 (sec Figure XXA'l). Although this is m empirical

agreement with the present work, Temay et_ al_. have not as yet

published evidence of a more conclusive nature to substantiate

'the existence of the two conformers as separate crystalline

entities.

Tcrnay and Chasar (181) have proposed that the pseudoaxial

proton of TXO is coupled to the aryl protons of the adjacent

209

FIGURE XXIV THE OXIDATION OF THIOXANTHËNE TO THIOXANTHËNE-10-OXIDE

H2Oa(3Ôt)'

i O

thioxanthëne thioxanthene-10-oxide

FIGURE XXV THE REACTION OF THIOXANTHËNE-10-OXIDE

ON NEUTRAL ALUMINA

2 L O I T O

neutral alumina

S ' ^ v ^ aprotic I

q solvents k r- \ " . . .

th ioxanthene-10-oxide thioxanthëne thioxanthone

FIGURE XXVI

pseudoaxial array j pseudbequatorial array ' H V' |

H Q and H •• represent the pseudoaxial and pseudoequatôrial protons, respectively, in

i

each of the conformers.

TWD STABLE CONFORMERS OF THIOXÀiNTHENE-10-OXIDE

211

phenyl rings (see Figure XXVI). Their proposal is supported by the observation that the n.m.r. signal for the upficld doublet of the Ali quartet is. considerably broadened (based on width at ^ half-height) compared "to" the' doûïifi'ëïd ""doublet "when' TXO is dis­solved in chloroform-d [see Figure'XXVII(a) ]. This observation is further supported'by decoupling experiments described by Ter-nay, Ens g Herrmann,and Evans (ISA) in which irradiation,of the aryl protons (2.61 T) sharpened the "'signal of the broadened up-field-doublet almost three times more than that of"the downfield doublet. -

From this- and other evidence arising from an extensive in­vestigation of conformationally restricted derivatives of TXO, Temay ejy ad. hav/ proposed'that TXO prefers' the pseudoequatorial array^in chloroform-d (see Figure XXVI). These workers have ob­served, however, that if TXO is dissolved in trifluoroacetic "acid "the broadened doublet signal of the ÀB quartet lies down-field to that of a sharper doublet [see Figure XXVI1(b)]. This apparent interchange of shift positions for the doublets has been interpreted, as evidence-for a conformational change such

that TXO now occupies the pseudoaxial array (see Figure.XXXAH) , *• ''''-A

•f- " • » ' * -

while the broadened douillet signal continues to represent .[the pseudoaxial proton of the methylene group (183) .

L

The hydrQgen-deuterium exchange reactions for.the methylene protons of TXO occur rather rapidly in the slightly alkaline'

212

I

I—i—l—I—i—J—ill I » • • 1

5-5T 6-OT \ 6-5T

(Q) TXO dissolved in. CDC I , .

» » i • • • » « • • • » • 5-OT . 5-5T 6-0 X

<b) T X O dissolved In C F 3 COO H

FIGURE XXVII PORTIONS OF N.M.R. SPECTRA OF 'HP SHOWING

THE AB QUARTET OF THE METHYLENE PPXTTONS

media of" deuterium oxide and triefhylaminc, with the more labile methylene proton be in;' represented by .the down fi eld, doubl et of tire AR quartet in the n.m.r. spectra (cf. figure XXVII). Thi: i s "fast-exchange" proton "co"rre's"pon"ds""'tb "the methylene proton Te may et -al . lK^T(;itcd\s occupying 'the pseudoequatorial position when TXO is dissolved i nyhlorofonn-d. . In the initial stage of the exchange reactions, an unresolved triplet signal located' si i.girt 1 y to high field of the upfield doublet shift of the methylene quar­tet (see' Figure ..XXVI11) increases rapidly with: time. This' signal •represents the -HILT- ol a dias'tercoisomcr, the proton of which corresponds to the methylene proton which is represented by the

upfield doublet of the AH quar'tet in the n.m.r. spectrum of un-reacted protium 1X0. The location of the unresolved triplet ar­ising from the -011b- of the diasterOoisomcr then, in effect, labels the upfield doublet of the methylene, such that the twb doublets of the At quartet are distinguishable in n.m.r. spectra of par­tially deuterated TXO. Since the n.m.r. absorption signal for the -(3 HI- ol the dinstereoisoiner does not change shift position with respect to the A and-B douillets of the quartet, i.e., remains upficld, when samples of TXO and partially deuterated TXO are solvated by trifluoroacetic acid, chloroformed,and dimethyl sul-foxide-dc, respectively, (see Figure-XXVIII) , it can then be assumed that the methylene protons of protium TXO do'not inter -cliange n.m.r. shift positions with respect to each other Ln these solventSi . 4

j FIGURE XXVIII PORTIONS OF N.M.R. SPECTRA OF TXO MICH SHOW THE AB QUARTET OF THE

i • •• PROTIUM lE HYLENE AND THE uMESOLVED TRIPLET OF ONE OF THE PARTIALLY -! • '; DEIjTERATED TXO DIASTEREOISCS-ERS

5 0 T 5-5T: 6 0 T

(a) protium TXO and partially deuterated TXO dissolved in CFsCOOH

j 6 -OT 6 -5T

(b) protium TXO and partially deuterated TXO dissolved in CDCI3]

5-5T 6-OjT 6-

(c) protiura TXO and partially deuterated TXO dissolved in CTJjSOCDa

215

This observation is directly opposed' to the supposition of Temay cyt_ al_. (173, 185) which states that the n.m.r. signal of the proton occupying the pseudoaxial position is downfield to

fluoroacetic acid, but is upfield,when TXO is dissolved in chloroform-d and carbon tetrachloride. If the conformational • change proposed by Tenia}'-and co-workers for' TXO is correct, namely that TXO changes from a pseudoequatorial array in chloro-form-d to a pseudoaxial array in trifluoroacetic acid (as evi­denced by an interchange of n.m.r. shift positions for the pseudo-axial and pseudoequatorial protons) , then the present results can only be interpreted to mean that an extremely rapid exchange pro­cess occurs in which all the cliastereoisomer, represented by the -upfield unresolved triplet, must be converted exactly and only to the other diastereoisomer. The'requirements of this exchange -aremdoubt ful~iirde7f~m but are even more unlikely

-when the hypothetical!}- exchanging species are subjected to the highly acidic medium of trifluoroacetic acid, .y

Regardless of whether the aforementioned conformational change of TXO occurs or does not occur with the appropriate change in solvation, the present work would appear to suggest that the broadened doublet of the AB quartet does not always represent the same methylene proton, but indeed can represent the n.m.r. signal of either the pseudoaxial or pseudoequatorial proton. Since the effects of n.m.r. signal broadening are not

RI-,y

likely to be experienced by the pseudoecpuatorial proton as a result of aryl proton coupling [cf. (184)] , and in view of the ' fact that the decoupling experiment described by Ternav et al. (185)- could-not lie satisfactorily reproduced in the 'present'"work, the explanation given aby Ternay, Ens, Herrmann, and Evans, namely that n.m.r. signal broadening of one of the "methylene doublets of TXO is a result of aryl proton coupling, must be suspect.

217

' 7-3. SUGARY '

From Hie present investigation of two conformationally res-tricted.. s.ul.foxides-.-na ^ and thioxanthene-10-oxide,.the following may be concluded:

(1) The methylene protons adjacent to the sulfoxide group in 'each compound retain their n.m.r. shift positions with respect to each other regardless of whether the compounds-arc solvated by dimethyl sulfoxide-d6 or trifluoroacetic acid. This observation is contrary to that noted for-the methylene protons of phenyl­sulf inylaectic acid, but is in agreement in this'respect with prior investigations of other sulfoxide systems.

(2) Although a preferred confonTiation/h^

reported for thioxanthëne-10-oxide (183), the results of the present investigation dcynot lend substantiation to the existence of preferential conJaryrmje — or 9-thia-lJ ,10-dihydrophenanthrene-9-oxide,, but rather imply tliat

the conformers of each compound are in rapid equilibrium. ,(3) Tire downfield doublet of • the AB quartet in n.m.r. spec­

tra of thioxanthëne-10-oxidc represents the more labile-methylene proton of the compound, while the more acidic methylene proton of

9-thia-'9,10-dihydrophenanthrene-9-oxide is signalled by the up-field doublet of the AB quartet in n.m.r. spectra of the latter.

(4) When dissolved in aprotic solvents and exposed to

alumina, thioxanthëne-10-oxide appears to undergo a novel

/

disproportionation to yield thioxanthone and thioxanthene. Preliminary experiments indicate that a similar-reaction may occur in the presence of dilute.aqueous, sodium hydroxide [cf.. (182)].' •

• Further quantitative empirical examination of the phenyl­sulf inylacetic acid system may be warranted. Investigation of specific proton/water participation in the solvation of the acid, and the corresponding role played, by deuteron/deuterium oxide in the hydrogen-deuterium exchange process at the methy­lene position remains a priority. * As'stated above, the factor previously considered to predominant in the exchange process was the effect of the intrinsic asymmetry of the sulfoxide group on the relative chemical reactivity of the adjacent methylene protons 'in conjunction with competitive conformer stability?1 This notwithstanding, solvent participation may also be a significant factor in the proton-deuteron exchange process'at the methylene position of phenylsulfinylacetic acid.

Tire intrinsic asymmetry' of the sulfoxide group of the acid may be destroyed by solvation in aqueous media [c.f. (146); see Figure XXIX], but the solvated carbanions will lead to diastereotopic" selectivity only if the rate of con­formational interconversion, through internal rotation and inversion, is slow compared to the rate of proton-deuteron

1 • . • . • ..219 •

\ •• ; ,

i FIGURE XXIX NEWMAN PRfAJECTION DIAGIWS (VIEWED ALONG THE S-C BOND)

OF POSSIBLE SOLVATED STRUCTURES FOR Fmm^HNiXACETIC ACID ~ AmJ\NIOI IN-A(~*JEC / L l ^ - . - "-'

OH 0~

COOH C O O *

solvated pherr/lsulfinylacetic solvated phenylsudfinylacetate acid in aqueous acidic media anion in aqueous alkaline media

220

exchange [sec Figure X2vX].* Since .stereoselectivity is evi­

denced by unequal populations of the diastereoisomers arising

from proton-deuteren exchange, the rate of interconversion

"Tiïrd7_]ience the - rate bi inversion, must-be less-than- the ra ; ••

of exchange. The implication, that inversion significantly

affects the product ratio of the diastereoisomcrs, however,

only requires that the rate of oxygen exchange at sulfur be

competitive with that of proton--deuteron exchange.

In one of a series of papers Oae (145), lias reported the -

rate of oxygen exchange at sulfur for three sulfoxides in thé

presence of carboxylic acids of varying acidity. Although

quantitative measurements were not recorded for..phenylsulfinvl•

acetic acid, an approximation of the rate of the sulfoxide

oxygen exchange 'at 25°C would yield a value'not less than 10"7

sec - 1 to within one order of magnitude. If the deuterium

exchange-a~eaction--at--the~ady

to be pseudo-first order, the rate of exchange is also

^Irrespective of the rate of interconversion, unequal populations

of the diastercoisomers may arise as"a consequence of a secondary

isotope effect which would produce^stereoselectivc collapse of

the solvated acid subsequent to creriteratiop as shown in Figure

XXX. It is doubtful, however, whetfieiythe difference in the

populations of tire diastereoisomers can be totally accounted for

by a-'secondary isotope effect.

221

FIGURE XXX NEWMAN PROJECTION DIAGRAMS (/VIEWED ALONG THE S-C BOND)

OF PBOrai-DEUIERON EXCHANGE UN A SOLVATE!) PHENYLSUIJIrJYLAC ACID CTNEOFfrER UNDER OCMDITIONS OF. RAPID

d-TNFOT MATlClLOT Ph

addition o^Y^>© of D 20 l

COOH

unsolvated conformer

Ph

- ^ r ^ O D oo^y^oo COOD COOD

equal populations of two enantiomeric carbanions

equal peculations of two enantiomers

Ph Ph

Ph 3 & COOD

A '

COOD COOD

(rapid interconversion will suppress stereoselectivity)

-D2Q. secondary isotope effect* — _ ,

1 +

Ph

COOD

D two mirror - image pairs of diasteteoisoxners 3

*Irrespective of the rate of interconvjsrsion, unequal populations of the diastereoisomers may arise as a consequence of a secondary isotope effect.' On this basis, the populations of A and D might be expected to differ from those of B and1 C.

approximately 10 7 sec"1 at room temperature.

Recently, IXrrst and co-workers (185) have shown that the

differential kinetic -'acidities of the .diasterco'topic protons

in-benzyl-methyl-sulfoxide - depend on the--nature-of the base "~

and the solvent system, indicating that proton-deutcron ex­

change rates 'are not solely intrinsic properties of the unsol-

vatcd sulfoxide and related carbanions. IV Amove ancf Brauman

(18b) have also questioned the validity of the assumption [see

Wolfe et al_. (158)] that the product ratios of" the monodeuter-

atcd conformers of benzyl methyl sulfoxide obtained via

quenching techniques reflect the relative stabilities of the

corresponding carbanions. From their kinetic study of the

ixites of proton-deutcron exchange and epinnerization of methyl

1-phenylethyl sulfoxide, n'Amore and Paauman conclude that 'the

rate of interconversion between the diastereoisomers may be

coiuparable"'torthe~rat"e;'"oi"qu'enchingT Hence7"~the~resûTtYng "

product ratios are not necessarily a measure of relative car-

banion stability nor are they indicative of proton lability.

Tins conclusion is supported by Nishihawa and Nishio (187),-

who report a similar finding from studies of the effect of

quenching on proton-deuteron exchange in benzyl methvi sul­

foxide dissolved in tetrahydrofuran.

Hence, an analysis of the possible effects of solute-

-solvent interactions on the reactivity of the methylene

protons oT phony 1 sulfinylacctic acid would necessitate the determination ol" the rate oJ" racemizatjon of an enantjomer yyjd_tjy ^

sulfur. A comparison of these values with the rate of

proton-deuteroir exchange at the methylene position would then

•perhaps offer some indication of the significance of solute-

-solvcnt" interactions in aqueous media and suggest the rela­

tive importance of solvated species in the proton oleuteron

exchange process.

. APPENDIX I

A DESCRIPTION OP THE TINSLCY AND GENITAL RAIMO

I MP E DAN Q • COMPARATOR BRIDGES .AND TIC • CONSTANT

TWIIRATTII1E BATHS '

A simpJi fied block diagmim of the 48% Tins!e>\Bridge with auxi 1 iary equipment is shown in Figure XA'XI. 'Che Bridge arid, "ii accessories we re assembled according to the description of ~''' -KoberStjon-(• 188) , but minoivmodifications- iivtbis design were necessary because of the commercial unavailability of some of the components described. • _

A Hewlett Packard oscillator (model 200' AB) supplied the alternating current (At7) at 1000 cycles per second (ops) to the bridge. A constant voltage. powcr source (117 + 1 vo11) for the oscillator was supplied by a Sorensen AC regulator (ARC 5000

model) connected to a 120yolt majurs output . " • *" ' •

B.alancing, ol .the bridge was obtained bv observing a-bissajous pattern on the oscilloscope (Hewlett Packard 1200 mode].) which derived its signal frdm a 1000 cps high gain > _ amplifier (see P igure 'XXXI I) . 'Ihis amplifier was connected to

-thc~liri'dgc~outpvf^thTougïinPS?S^rtTfânsTôrincr, ancTthé a j n p f f r i c i

output was fed through shielded leads to the vertical input plates of the ose illoscope.[For a more detailed discussion, see ( . 4 4 ) ] .

The G.R.I.C., type 1005-A, is designed to measure the magnitude and phase angle difference between two external impedances. The instrument essentially consists of a •special self-contained bridge measurement system, composed of a signal • source, a bridge and a detecting circuit (sec Figure XXXIII).

' FIGURE XXXI A BLOCK DIAGRAM OF THE TTNSLEY "œNTOTANŒ BRIDGE CIRCUIT

Isolating Transformer

(xfmr;

•678A

.9C£

Phase Shifter

Isolating Transformer

000 CPS. High Gain Amplifier

Ac -9 O

I/P Detector o/p

Electrolytic Conductivity Bridge 4896

Unknown resistance

FIGURE XXXIII • *

A DIAGRAM OF THE IMPEDANCE BRIDGE CIRCUIT FOR THE G.R.I.C. (TYPE 1605-A)

I605AH

The bridge .proper has two externa] impedances to be compared and two high])' precise 1:1 ratio amis. Since these anils arc equal to within 0.00015, the accuracy of the impedance measure­ments "depends largely upon the precision of the external stnn-dard, a General Radio resistance box, type 1 4 7.2. This decade box lias a resistance range of 0 .1-111 ,111 çfi and the accuracy of the resistance increments was' given |as -t 0.055. The bridge was calibrated against a Leeds and Northrup (model 1750X5) standard resistance box with low frequency dépendance, and the resulting discrepancy was less than 0.OK. between 100 A and 50,000 0.

. 5y dotai led description of the oscillator, amplifier and bridge circuit is given in the General Radio operating instruc­tions for an Impedance comparator, type .Po05-A. .

yonyuint Temperature Bath. - The bath assembly consisted of a 5 ' " ' 21'1'' x 24" mctul lxaiiicd_u))it.\vluch-supi)or.ted-two--stainless--stoe] tanks (each 25" x ]5" x 15"!, one mounted above the other, idiich cure insulated by a 1" coating of styrofoam on the outside As constant cooling and continuous heating were necessary to maintain tempera turc control, the lower tank was used as a cooling bath and the upper tank served as" the.constant tempera­ture hath.

tooling coils constructed from ca. 25 ft of copper tubing (5,/S" diameter] wound in five spirals (era. 2'; apart) wore installed 5 /S " above the bottom of the upper bath. These coils were connected to the lower cooling bath with heavy, insulated

229

rubber tubing. The flow of coolant (water at 21°C) circulated by a centrifugal pump (maximum rate, 1.5•1/min)'from the cooling bath til rough the cooling coils in the upper hath was regulated -by' a~'bypass arrangement with a dual control valve system set in the tubing.

The temperature of the water in the cooling bath was main­tained by the cooling coil&fïom a Tecumseh refrigerator (E hp). Til es e coils were constiaicted of ca., 100 ft of copper tubing • (5/8" diameter) wound'in six spirals' about 8" apart and were supported in the lower bath by a metal frame. The water in this bath was circulated over the refrigeration coils hy means of a stirrer (Redmond, type T, model 0407;'1/10 hp) mounted on the side of the bath. The temperature of the water was regulated to 21.00 ± 0.25°C by means of a Fenwal Electronics thermistor IG252J2) m a modified Wheat stone Bridge circuit (see Figure

The constant temperature bath was filled with Yoltesso transformer oil -(180) which.was agitated hy means of a Cenco centrifugal Electric stirrer (1/20 hp; rated circulating capacity for water, 105 gallons/min) mounted at one end of the bath. The temperature of the oil was controlled by a Tronac Regulator (ETC - 1000A).

Tliis regulator essentially consists of a background heater

(250 watts) ahd an intermittent knife heater (250 watts). The

latter is controlled by a thermistor probe and temperature

FIGURE XXXTV' \ A DIAGRAM OF THE 'TEMPERATURE SENSOR AND KECAILATOR CIRTJUTT

Q|, Q £ l Q 5. = SK3060 D, , D 2. - IN 5060 j , -Reloy = 130 A, l3tio. (DC) j Î

controls set in a Wheats tone Bridge circuit which is excited hv a stabilized AC source. The Tronac is capable of regulation to f 0.001°C, with long term drift of less than ± 0.005°C per week. A full description of its specifications' and operation is detailed in a manual supplied by Tronac, Inc.

The temperature of the bath was maintained at 25.000 ± 0.005°C for long periods of time. Over several hours the temperature varied less than ± 0.0024°C. Temperature control of the bath was facilitated by its location in a constant temperature, air-conditioned room.

u

APPENDIX II FORTRAN IV COMPITTER PROGRAMS PX1PLOYED IN

HIP: CALOJLATION OF TIERNPDYNAMIC EQUILIBRIUM

.CONSTANTS AND -ISOTOPE EFFECTS

252

C ROBINSON AND STOKES METHOD • -

DIMENSION C ( I O O ) , E C ( 1 0 0 ) , A L F ( 1 0 0 ) , Y ( 1 0 0 ) , D E N O M ( 1 0 0 ) , ALI(

1100) ,BLE (100) ,YY (100) ,DENON (TOO),GOLE (100) ,Z (10Q) ,EP(10Q)

~'~ 2 , S ( 1 0 0 ) , A K A ( 1 0 0 ) , D E V ( 1 0 0 ) , A D E V ( 1 0 0 )

5 PRINT 3

3 FORMAT (1X.26HMACINNES-SHEDLOVSKY METHOD)

READ 2 ,AL0 ,BETA ,BA,B1,B2

2 FORMAT ( 6 X , F 6 . 1 , F 7 . 4 , F 8 . 5 , F 7 . 4 , F S . 4 )

L = 0

e 20 L = L + 1

READ 1 , C ( E ) , E C ( E ) ,LAST

1 FORMAT ( 6 X , E 1 1 . 4 , F 9 . A , I 2 )

IF(LAST)20,20,30

30 K=L . .

EL=L

PRINT 18

18 FORMAT (1X,1311C0NCENTRATI0N,3X,8HEQUIVC0N,3X,8HLAMBDA 1 , 5

I X , l l l l E Q U l L . C O N S T , 3 X , 9 H D E V I A T I O N )

sumk=o.o

13 A L F ( L ) = E C ( L ) / A L O

X=B1*AL0+B2

Y ( L ) = S Q R T ( A L F ( L ) * C ( L ) )

D E N 0 M ( L ) = 1 . + B A * Y ( L )

2 1 A L I ( L ) = A L O - ( X * Y ( L ) ) / D E N O M ( L )

B L F ( L ) = E C ( L ) / A L I ( L )

Y Y ( L ) = S Q R T ( B L F ( L ) * C ( L ) )

D E N O N ( L ) = 1 . + B A * Y Y ( L ) — . i , n—.— t , u — L — 1-.. .i—;—••• ... •.— i

GOLE(L)•»-BETA*XX ( L ) / D E N O N ( L ) -

Z ( L ) = 2 . 3 0 2 5 9 * G O L E ( L ) .

E P ( L ) = E X P ( Z ( L ) )

S ( L ) = ( B L F ( L ) * * 2 X * E E ( L ) * * 2 * C . ( L )

A K A ( L ) = S ( L ) / ( 1 . 0 - B L F ( L ) ) ' ' '

S U M K = S U M K + A K A ( L )

9 C O N T I N U E

A V K A = S U M K / E L .

S U M D = 0 . 0 •

D O 4 L = 1 , K

A D E V ( L ) = ( A V K A - A K A ( L ) ) * * 2

SUMD=SU> n>+i\DEV(L) > :DEV<I;)="("(AVKA-5AKAXL")07AVX\">*IOO: ~ : ~

r

P R I N T 14,C(L).,EC(L) , A L I ( L ) , A K A ( L ) , D E V ( L )

14 F O R M A T (IX,E11.4 , 5 X ,F 9 . 4 , 4 X , F 7 . 2 , 3 X ,E l l . 4 , 3 X , E 1 1 . 4 )

4 C O N T I N U E

E D E V = S Q R T ( S U M D / ( E L - 2 . ) )

P R I N T 9 2 ,EDEV

9 2 F O R M A T ( I X , 2 2 H A V E R A G E D E V I A T I O N I S , E 1 1 . 4 )

P R I N T 9 1 . A V K A

9 1 F O R M A T ( 1 X , 1 5 H A V E R A G E K A I S , E 1 1 . 4 ) .

C A L L E X I T ,

E N D

254

C I V E S M E T H O D P

, • D I M E N S I O N C ( I O O ) , E C ( 1 0 0 ) , A L F ( 1 0 0 ) , C I ( 1 0 0 ) , Y ( 1 0 0 ) ,X('X0dl,CAL i

ÎCY(IOO),DIB(100),AKA(100)~DEV(100),ADEV(100),Z(10O),ZZ(lOO)

—iTziTyinïtr:**...... ..—.. ..... -. — - —

4 F O R M A T ( 1 X , 1 1 H I V E S M E T H O D ) ' •' ' •

READ 2,ALO,BETA,BA,Bl,B2 '

2' F O R M A T ( 6 X , F 6 . 1 , F 7 . 4 , F 8 . 5 , F 7 . 4 , F 8 . 4 )

P R I N T 3 L , A L O

3 1 F O R M A T ( 1 X , 1 2 H L A M B D A ( 0 ) ' = , F 6 . 1 ) .

- L = 0

' 2 0 L = L + 1

R E A D 1,C(L),EC(L),LAST

1 F O R M A T ( 6 X , E 1 1 . 4 , F 9 . 4 , I 2 )

/ I F ( L A S T ) 2 0 , 2 0 , 3 0

3 0 K = L

E L = L -TV

P R I N T 8 8 • \

8 8 F O R M A T ( 1 X , 8 H S L O P E , 6 X , 1 1 H I N T E R C E P T , 3 X , 1 0 H E R R O R I N B , 3 X

l,14HERROR IN S L O P E )

6 0 S U M K = 0 . 0

S U M X = 0 . Q

S U M X Y = 0 . 0 .

S U M X X = O . o

DO 25 L = 1 , K

A L F ( L ) = E C ( L ) / A L O

A = B 1 * A L 0 + B 2

• C I ( L ) = S O R T ( A L F ( L ) * C ( L ) ) - - - . •• ' " •

Y ( L ) = F X ( L ) + A * C I ( L )

Z ( L ) = 2 . * B E T A * C I ( L )

Z Z ( L ) = 1 0 . * * Z ( L ) :

X ( L ) = ( G ( L ) * E C ( L ) * * 2 ) / ( Z Z ( L ) * ( A L O - A * C T ( L ) ) )

SUFLX=SUÎ-K+X(L) .

SUMY=SUMY+Y(L)

SD7TXY=SUMXY+X ( L ) *Y ( L )

SUî-LXX=SÙf'LXX+X ( L ) * * 2

DENOM=SU>rX**2-OK*SU7>LX'X

S LOPE = (SUMX*SlRTY-OK*SUMXY) /DENOM w

B=(SUr-K*SU>iXY-lsWn ' *SUt :LXX)/DENOM

C A L C Y ( L ) = S L O P E * X ( L ) + B

D I B ( L ) = ( Y ( L ) - C A L C Y ( L ) ) * * 2

SUMD=SUMD+DIB(L) £ ^

RE=0 . 6 7 4 5 * S Q R T ( S U o l D / ( E L - 2 . ) )

ERROR=RE*SQRT(SU>LXX/(-DENOM))

E R B = R E * S Q R T ( O K / ( - D E N O M ) ) •

PRINT 6 , S L O P E , B , E R R O R , E R B

FORMAT ( 1 X , E 1 1 . 4 , 3 X , F 9 . 4 , 3 X , E 1 1 . 4 , 5 X , E 1 1 . 4 )

D L F = A B S ( A L O - B )

DO 3 L = 1 , K

256

PRINT 5 0 . D I F

50 FORMAT ( l X , 3 7 F i D I F F E R F v N C E , L A M B D A ( 0 ) - l / l N T E R C E P T I S , F 7 . 2 )

I F ( D I F - Q . 0 1 ) , 1 5 , 1 5 , 1 7 ' "

; ' . ' "17 I F ( D I F - 2 0 . ) 1 6 , 1 6 , 9 5 ' "

16 ALO=B ' ' •

. G O TO 60 ".

15 S A K A = - 1 . / S L O P E .

PRINT 23 , SAKA

23 FORMAT ( 1 X , 1 9 H K7A FROM S L O P E I S . E 1 1 . 4 ) -

DO 29 L = 1 , K ' ' ]

A K A ( L ) = X ( L ) / ( B - Y ( L ) ) ' '

29 SUMK=SUMK+AKA(L) . ' • , ; '

AVK5A=SFJMK/OK ' '•

PRINT 9 3 . A V K A

9 3 FORMAT ( T X , 15HAVERAGE K3A I S , E 1 1 . 4 )

PRINT 33

3/3' FORMAT ( I X , 13HCONCENTRATION , 3 X , 1 1 H E 0 U I L . CONST, 3 X , 13H DEVI

/ 1ATION) ' L K { ^ . •' . .

\ ^ S U M E = O . O

J DO 45 L=1,K7 '

D E V ( L ) = A V K A - A K A ( L ) - '

A D E V ( L ) = ( A V K A - A K A ( L ) ) * * 2

S U T M B = S U M B + A D E V ( L ) . ^

PRINT 4 2 , C ( L ) , A K A ( L ) , D E V ( L ) '

4 2 FORMAT ( I X , E 1 1 . 4 , 5 X , E 1 1 . 4 , 4 X , E 1 1 . 4 )

45 CONTINUE V

EDEV=SQRT(SUMB/ (EL -2 . ) )

PRINT 92 ,EDEV

92 ' FORMAT (1X.22HAVERAGE DEVIATION IS

95 ' ' 'CONTINUE'' - : _" ".',' ""'

CALL EXIT

END . • -

, E 1 1 . A )

)

FUOSS METHOD

DIMENSION C ( 1 0 0 ) , E C ( 1 0 0 ) , A C ( 1 0 0 ) . A L F ( I O O ) , Z ( 1 0 0 ) , F 1 ( 1 0 0 ) , F

1 2 ( 1 0 0 ) , F 3 ( 1 0 0 ) , C O L E ( 1 0 0 ) ' , Q ( 1 0 0 ) , E P ( 1 0 0 ) , Y ( 1 0 0 ) , S ( 1 0 0 ) , X X ( 1

200) , A K A ( 1 0 0 ) ' , C A 1 Ç Y ( 1 0 0 ) , D I B ( 100) . , DEV ( 1 0 0 ) , A D E V ( 1 0 0 ) - -,

5 PRINT 4 • •.

4 FORMAT (1X,22HFU,0SS ITERATION METHOD)

READ 2 , A L O , B E T / y , B A , B l , B 2 "

FORMAT ( 6 X , F 6 . 1 , F 7 . 4 , F 8 . 5 , F 7 . 4 , F 8 . 4 )

20 L = L + 1

READ 1 , C ( L ) , , E C ( L ) ,LAST

1 FORMAT ( 6 X , E 1 1 . 4 , F 9 . 4 , I 2 )

IF(FAST)2o\ 2 0 , 3 0

30 K=L

EL=L

PRINT 88

88 FORMAT ( I X , 8 H SLOPE,6X,11H1/ INTERCEPT,3X,10UERROR I N B , 3

1X,14HERR0R I N SLOPE)

60 CONTINUE

3 1

PRINT 31 ,ALU .

FORMAT (1X ,12HLAMBDA(0 )= , F 6 . 1 )

21 L=0

SUMX=0.0

SUMY=0.0

SUMXY=0.0

SUMXX=0.0

DO 9 L = 1 , K V

(

X=B.1*AL0+B2 Z(L)=X*SQRT(AC(L)"/AL0**3)

F2(L)=1.-Z(L)*SQRT(1:. / F U E ) )

F3(L) = l.-Z(L)*sqRT(l ./F2'(L)) ALF(l9=FX(L)/(AL0*F3(L))

f : 0 LI • ( L ) = - F, E T A * S ( II {T (AL F ( L ) * C ( L ) • )

Q ( L ) = 2 . 30259*GOLE(L)

EI'(L)=EXP(0(F)) I

Y(L)=F3(L)/EC(L) l

XX j( L ) =,C ( L ) * EC ( L ) *E P ( I, ) * * 2 / F3 ( L ) ,sukx=su>Lx+xx(L) .• '• '

S U|L\XX = SUMXX+XX (L) **2

Suk\T=5in>lXY+XX ( L) *Y (L) OK=K | i

D F. N 0 M=S UT FX **2-0K*'SUM XX SLOPF= ( S U M X * S U M Y - O K * S U M X , i ) / D E N O M

B= (SUFLX*SU \T-SU>rt'*SlJ>C-CX) /DENOM F=1.0/B ,' '

SUMD=0.0 • ' ; .

DO 91 L=l,K CALCY(L)=SLOPE*XX(L)+B

DIB(L)=(Y(L)-CALCY(L))**2 SUFiD=SUMD+DIB(L) /

RE=0.6 745*SQRT(SUMD/(EL-2.))

_ERROR=RE*SQRT (SUMXX/ (-DENOM) ) •

ERB=RE*SQRT(OK/(-DEN0M)) '

PRINT 6,SLOPE,F,ERROR,ERB

_FiORJ^T_a>^

DIF=ABS(ALO-F) ; •

PRINT 5 0 , D I F • . ,

FORMAT ( I X , 3 7HDIFFERLNCE, LAMBDA(0) -1 / INTERCEPT IS ,

I F ( D I F - 0 . 0 1 ) 1 5 , 1 5 , 1 7 '

I F ( D I F - 2 0 . 0 ) 1 6 , 1 6 , 9 5

ALO=F ' '

CO TO 60

S A K A = 1 . / ( S L 0 P E * F * * 2 )

,PRINT 23,SAKA '

FORMAT ( 1 X , 1 9 H KA FROM SLOPE I S , E 1 1 . 4 ) ' '

PRINT 33 ' • • ' ' r-

JLl^'rllL jXtr ic 3X., 11HEQU I L . CON S T , 3X , 1411

1 V I A Ï I O N ) •

SUMK=0.0

DO 29 L = l , R '<

S ( L ) = ( A L F ( L ) * * 2 ) * ( E P ( L ) * * 2 ) * C ( L )

A K A ( L ) = S ( L ) / ( 1 . O - A I F ( L ) )

SUMK=SUMK+AKA(L)

AVKA=SUM0/OK

^SUMB=0.0

DO 45 L = 1 , K

DEV(L )=AVKA-AKA(L ) . 2 -

ADEV (L ) = (AVKA-AKA(L) ) * * 2

241

SUMB=SUMB+ADEV(L) /

PRINT 4 2 , C ( L ) , A K A ^ L ) , D E V ( L )

42 FORMAT ( IX , E l 1 . 4 , 5X , E l l , 4 , 4X , E 1 1 . 4)•

45 CONTINUE '

PRINT 93.AVKA

93 FORMAT ( I X , 15HAVERAGE KA IS . , E 1 1 . 4 )

EDEV=S0RT(SUMB/ (EL -2 . ) ) 2" ;

PRINT 92,EDEV '

" • : FORMAT ( I X , 22HAVERAGE 'DEVIATION IS , E 1 1 . 4 )

95 CONTINUE

CALL E X I T

END

V i f ^ 2 4 .

SHEDLOVSKY 1 METHOD

DIMENSION C ( I O O ) , A C ( 1 0 0 ) , E C ( 1 0 0 ) , Z ( 1 0 0 ) , F l ( 1 0 0 ) , F 3 ( 1 0 0 ) ,AL

i r ( 1 0 0 ) , .GOLE(100),0(100),EP( IOO) , Y ( 1 0 0 ) , X X ( 1 0 0 ) , S ( 1 0 0 ) ,AKA(

- 2 1 0 0 ) , D E V ( 1 0 0 ) ,-CALCYÇlOO) ; D I B ( 1 0 0 )

100 PRINT 26 . • • .

26 FORMAT ( I X , 17HSI1EDL0VSKY METHOD)

READ 2 , A L 0 , B E T A , B A , B 1 , B 2

2 FORMAT ( 6 X , F 6 . 1 , F 7 . 4 , F 8 : 5 , F ? V 4 , F 8 . A )

F=0 ..; • '

20 L=L-t- l

READ 1 , G ( L ) , E C ( L ) , L A S T

1 FORMAT . ( 6 X , E 1 1 . 4 , F 9 . 4 , I 2 )

I F ( L A S T ) 2 0 , 2 0 , 3 0

30 K=L

EL=L

- P R I N T - 8 8 \

88 F O R M A T (IX,811 S L O P E ,6X , 1 1 H 1 / I N T E R C E P T , 3 X , Î O F E R R O R I N B ,

1 3 X , 1 4 H E R R 0 R I N \ S L O P E )

6 0 C O N T I N U E \ l, - SUMX=O.Û *

S U M X X = 0 . 0

S F M Y = 0 . 0 ~ .

S U M X Y = 0 . 0 ,

D O 4 0 L = 1 , K ' . .

• A C ( L ) = E C ( L ) * C ( L )

X = B 1 * A L 0 + B 2

• Z(L)=X*SQRT(AC(L)/(ALO'**3) )

F 1 ( L ) = 0 . 5 * Z ( L )

F 3 ( L ) = ( F 1 ( L ) + S Q R T ( 1 . + F 1 ( L ) * * 2 ) ) * * 2

A L F ( L ) = E C ( L ) * F 3 ( L ) / A L 0 ' '

• : - : - G O L E ( L - ) = - B E T A * S q R T ( A L F ( L ) * C ( L ) )

Q ( L ) = 2 Ï 3 0 ' 2 5 9 * G O L E ( L )

E P ( L ) = E X T ( Q ( L ) )

Y ( L ) = 1 . / ( F 3 ( L ) * E C ( L ) )

X X ( L ) = C ( L ) * E C ( L ) * E P ( L ) * * 2 * F 3 ( L )

SWK=SUILX+XX(L) ; ,

SUMY=SUMY+Y ( L )

SIRTXX=SIRIXX+XX(L) * * 2

3 SIR4XY = SUMXY+Y(L) *>2X(L)

40 CONTINUE • • *•

OK=K

DENOM= S UMX* * 2-OK * S.IFMXX

'—SLOPE= ( SUTC<*SLTrï-0}^

R = ( S UMX* SUMXY- SUMY * SUMXX) /DENOM

F = F . 0 / B ~]

D I F = A B S ( A L O - F )

SUMD=0.0

DO 91 L= 1 , K

C A L C Y ( L ) = S L O P E * X X ( L ) + B

D I B ( L ) = ( Y ( L ) - C A F C Y ( L ) ) * * 2

9 1 SuTtD = SUMD+DIB(L) .

22 R E = 0 . 6 7 4 5 * S Q R T ( S U M D / ( E L-2X)) ^

ERROR=RE*SQRT(SUMXX/(-DENOM) )

E R B ~ R E * 3 At (OK / ( -DENOM) )

WJ6,1

F O R M A T ( 1 X , E 1 1 . 4 - , 3 X , F 9 .4 , 3X , E l l . 4 , 5X , E l l . 4')

PRINT 6 ,SKOPE,F,ERROR,ERB

- P R I N T - 5 0 , D I E - • ""• \ ' i " •

• FORMAT ( I X , 37HD1FFEREÎ1CE , LAMBDA ( 0 ) - 1 / I N T E R C E P T IS , F 8 . 4 ) ' \ : . " .

I F ( D I F \ O . : 0 1 ) 1 5 , 1 5 , 1 7

\ !

I F ( D I F - 2 0 . ) 1 6 , 1 6 , 9 5

ALO=F

GO TO 60 • •' •

S A K A = 1 . / ( S L O P E*F * * 2 )

PRINT 2 3,-SAKA ' •

FORMAT ( 1 X , 1 9 H KA FROM SLOPE IS- , E 1 4 . 4 )

PRINT -5 •

FORMAT ( I X , 13HCONCENTRAT ION , 3X , 11HEQUIL . CONST , 3X , 13HO /O DE

1 V I A T I 0 N )

- S ^ K = 0 ' : O — V ' " ~ ~ ~ ' " ','v'

TDEV=0.0

DO 29 L = 1,K -

S ( L ) = ( A L F ( L ) * * 2 ) * ( E P ( L ) * * 2 ) * C ( L )

A K A ( L ) = S ( L ) / ( l . O - A L F ( L ) )

SUMK=SUMK+AKA(L)

A\T;A=SUT-IK/OK T

DO 45 L = l ,K 1

DEV(L) ' = (A \ aXA-AKA (L ) ) * 1 0 0 . /AVKA

PRINT 4 2 , C ( L ) , A K A ( L ) , D E V ( L )

FORMAT ( 1 X , E 1 1 . 4 , 5 X , E 1 1 . 4 , 4 X , F 6 . 2 )

T D E V = T D E V + ( A V K A - A K A ( L ) ) * * 2

2 4 5

A D E V = S Q R T ( T D E V / ( 0 K - 2 . ) ' )

PRINT 46„ADEV , i '

4 6 " FORMAT ( I X , 2 3 1 1 AVERAGE DEVIAT ION I S . ,E14.4)

-95 CONTINUE

CALL EXIT

" END

C L A S S I C A L M E T H O D \.

D I M E N S I O N C ( I O O ) , E C ( 1 0 0 ) , A C ( 1 0 0 ) , X ( 1 0 0 ) , C A L C Y ( 1 0 0 ) , D I F ( 1 0 0

1 ) , A I E ( 1 0 0 ) A . . .

L = 0

L = L + 1 '

R E A D 1 , C ( L ) , E C ( L ) , L A S T

F O R M A T ( 6 X , E 1 1 . 4 , F 9 . 4 , 1 2 )

I F ( L A S T ) 2 0 , 2 0 , 3 0 '

R= L .

P R I N T 35

F O R M A T ( 1 X , 1 3 H C O N C ' E N T R A T I O H , 3 X , 1 0 H L A M B D A X C , 4 X , 1 1 H R E C . L A

lMBDA)

SUMX=0.0 . • •

SUMXX=0.0

S U M Y=0.0 ' ' •

S U M X Y = O . O ' • -

DO 3 L = 1,K

A C ( L ) = E C ( L ) * C ( L )

X ( L ) = 1 , 0 / E C ( L )

P R I N T 1 4 , C ( L ) , A C ( L ) , X ( L ) '

F O R M A T ( I X , E l l . 4 , 5X ,E 11. 4 , 3 X , E l l . 4 )

SUt-FX=SUMX+AC(L)

SUMY=SUM\'+X(L) -

S ULLXX= S UM XX+A C ( L ) * * 2

S U M X Y = S U K X Y + X ( L ) * A C ( L )

0 K = K

DEN0M= S W f X**2-0K * S W C O :

\

SL0PE=(SII>K*SUT-IY-0K*SUÎ-1XY) /DENOM —

B= (SLIÎ-K*SUlC\Y-SU>fY*SlmLXX) /DENOM ' • > F = 1 . 0 / B '

PRINT 6 , SLOPE, F • ••- •

FORMAT ( 1 X , 1 0 H S L O P E I S , , E l l . 4 , 3X , 16111 / INTERCEPT I S , F 7 . 2 )

S A K A = 1 . / ( S L O P F , * F * * 2 ) .

PRINT 23 ,SAKA

FORMAT ( I X , 1911 KA FROM SLOPE I S ' ,FX11.4) _ •

PRINT _33 ' ' '

FORMAT ( I X , 1 0 1 1 CALC. 1 / L , 5 X , 10HDIFFERENCE)

SUMD=0.0 ,

DO 5 L = 1 , R

C A L C Y ( L ) = S L O P E * A C ( L ) + B

D I F ( L ) = X ( L ) - C A L C Y ( L )

A l F ( L ) = D I F ( L ) * * 2

SUMD=SUMT>+AIF(L) 2» r, ' PRINT 7 , C A L C Y ( L ) , D I F ( L )

FORMAT ( I X , E l l . A , 3 X , E l l . 4 )

CONTINUE

R E = 0 . 6 7 4 5 * S Q R T ( S U M D / ( O K - 2 . ) )

,ERROR=RE*SQRT (SUFLXX/ (-DENOM) )

ERB=RE*SORT ( O K / ( - D E N O M ) )

PRINT 91 ,ERROR

FORMAT ( 1 X , 2 3 H E R R 0 R I N INTERCEPT I-S , E 1 1 . 4 ) V

PRINT 9 2 , E R B

FORMAT (1X,1911ERR0R I N SLOPE I S , E 1 1 . 4 )

CALL E X I T

END

SHEDLOVSKY 3 METHOD -

DIMENSION C(100),AC(100),EC(100),Z(100),F1(100),F3(10O),AL

1 F ( 1 0 0 ) ,GOLE(100) ,0(100),EP(lOO) , Y ( 100) ' ,XX ( 100) ,S(100) ,AKA'(

?. i n n )-r.:~cr-: (m r )-:>7ïr(Tn 0 ) : :

: Ki NT 70- - ,

70 FORMAT ( I X , 12HSHEDL0VSKY 3 )

J = l , .

60 PRINT 1 0 0 , J

100 FORMAT ( I X , 12HCELL NUMBER , 1 2 )

J = J + 1

READ, 4 2 , A L O , B L O , C L O

42 FORINT ( 6 X , F 7 . 2 , F 6 . 2 , F 7 . 2 ) L

- READ 2 , B E T A , B A , B 1 , B 2

2 FORMAT ( 6 X . F 7 . 4 . , F 8 . 5 , F 7 . 4 , F 8 . 4 )

L = 0

READ 1 , C ( L ) , E C ( L ) ^ L A S T , F I N A L , '

1 FORMAT ( 6 X , E 1 1 . 4 , F 9 . 4 , I 2 , F 4 . 1 )

I F ( F I N A L ) 2 0 , 2 0 , 3 0

30 K=L

OK=K

PRINT 88

88 FORMAT ( 1 X , 8 H S L O P E , 6 X , 1 1 H 1 / I N T E R C E P T , 3 X , 1 0 H E R R O R I N B , 3

1X,14HERR0R I N SLOPE,3X,9HLAMBDA(0))

3 1 EL=L

DO 40 L=1,K

A C ( L ) = E C ( L ) * C ( L )

X = B 1 * A L 0 + B 2 :

. Z . ( L ) = X * S Q R T ( A C ( L ) / ( A L 0 * * 3 ) )

F l ( L ) = 0 . 5 * Z ( L )

F 3 ( L ) = ( F1 ( L ) .+S 0 RT ( 1. +F1 ( L ) * * 2 ) ) * * 2

A L F V L ) = E C ( L ) * F 3 ( L ) / A L O

G O L E ( L ) = - B E T A * S Q R T ( A L F ( L ) * C ( L ) )

Q ( L ) = 2 . 3 0 2 5 9 * G O L E ( L ) .

E P ( L ) = E X P ( Q ( L ) )

Y ( L > 1 ' . / ( F 3 ( L ) * E C ( . L ) ) "

X X ( L ) =C ( L ) * E C ( L ) * E P ( L ) * * 2 * F 3 ( L )

\CONTTTUJE

SUMX==0.0

sm-co:=o.o

SUMY ==0.0

SUMXY=0,.0

DO 3 L = Ï , K

sm'rx=sin-rx+xx(L)

S W = S U F F i ' + Y ( L )

SUîTX2X=SLttTX2X+XX(L) * * 2

SIFMXY=SUî-LXY+Y ( L ) * X X ( L )

i " \ DEIO-1=SUMX**2-OK*SUMXX

/

SLOPE= ( SuTK*SÛTrf-C)K*SulCCY) /DENOM

B= (SlT>LX*SLR-iXYr-SUîrY;*SU>iXX) /DENOM

. F = T . O / B '

sw-fr\=o.o

DO 9 1 T ^ l ^ K

CALCY(L ) = S L O P E * X X ( L ' ) + B ' >

' D I B ( L ) = ( Y ( L ) - C A L C Y ( L ) ) * * 2 ' ' '

9 1 SW-ff i=SWlI>+-DIB(L) 1 ^ * — - —

RE=0.6745*SQRT(SWlD/(OK-2.)) '

i:RKuR-RK*SiiKT(SrMXX/(-:>!•::.(P!) ) -.'-- ' •

• E R B = R E * S Q R T ( O K / ( - D E N O M ) ) '

PRINT 6 , S L O P E , F , E R R O R , E R £ , A L O • '

6 FORMAT ( 1 X , E 1 1 . 4 , 3 X , F 9 . 4 , 3 X , E 1 1 . 4 , 5 X , E 1 1 . 4 , 2 X , F 7 .

I F ( C L O - A L O ) 8 , 8 , 5

.5 ALO=ALO+BLO j i -

CO TO '31 " . ,

8 I F ( L A S T ) 9 , 9 , 1 0 ^ '

9 GO TO 60 . ' . 10 CONTINUE

CALL . E X I T

END u .

SHEDLOVSKY 4 M E Ï l I O D ^ ^ l DIMENSION C ( 1 0 0 ) ,EC ( l O O ) ^ ( T t l ^ o Ô ^ > A L

Î F ( I O O ) . G O L E ( I Q Q ) , 0 ( 1 0 0 ) , EP ( 1QQ) . S.LIOÛ.1.. AKJS a n n ^ A n K V - l i . n n . ) - .

P R I N T 26

26 • FORMAT ' (1X ,12HSHEDLEVSKY 4 )

J = l • '

6 0 PRINT 100 ,J -V

100 FORMAT (1X: ,12HCELL NUMBER , 1 2 )

J = J + 1

READ _ 4 2 , A L O , B L O , C L O

42 FORMAT ( 6 X , F 7 . 2 , F 6 . 2 , F 7 . 2 )

READ 2 , B E T A , B A , B 1 , B 2

2 _ FORMAT ( 6 X , F 7 . 4 , F 8 . 5 , F 7 . 4 , F 8 1 4 )

L=0

20 L = L + 1

READ 1 , C ( L ) . , E C ( L ) ,LAST , F INAL

1' ' FORMAT ' ( 6 X V E 1 1 . 4 , F 9 . 4 , 1 2 , F 4 . 1 )

.. I F ( F I N A L ) 2 0 , 2 0 , 3 0 *

.ftWv. v W " r 7 •' P R I N T 7 5

75

31

FORMAT ( 1 X , 9 H L A M B D A ( 0 ) , 3X , 10HAVERAGE K A , 3 X ,17HAVERAGE' DEVI •

RATION) . , * , •

EL=L . ', •

'STJMK=Ô.O '

DO. 40 L = 1,K . " a .

A C ( L ) = E C ( L ) ' * C ( L )

X = B 1 * A L 0 + B 2 |

Z ( L ) = X * S Q R T ( A C ( L ) / ( A L Û * * 3 ) )

JEXa)^0..^±Z.(-L-) — —

v' F 3 ( L ) = ( F 1 ( L ) + S Q R T ( 1 . + F 1 ( L ) * * 2 ) )

ALF(L)=EC(L9^,( ;L)/ALO ,

COLE (L) =-BETA*SQRT ( ALF (L.) *C (L) )

0( L ) = 2 . 3 0 2 59*GOLE(L) '',

E P ( L ) = E X P ( Q ( L ) )

S ( L)=(ALF(L)**2)*(EP(L)**2)*C(L)

AKA(L) =S (L) / ( 1 . O-ALF(L) )

SUMK=SUMK+AKA(L)

CONTINUE

AVTG\=SUMR/OK

SIMD=0.0 - '

D O ' 4 5 L=1_,K

ADEV(L)=(AVKA-AKA(L))**2

SUMD=SLn-ID+ADEV(L)

EDEV=SQRT(SUMD/(.ELV-2. ) )

PRINT 9 1 , ALO , AVT2A, EDEV'

FORMAT'.( IX ,F7.2 , 4X,E11.4 , 5 X , Eli ' . 4 )

IF(CLO-ALO)8,8,5

ALO=ALO+BLO

GO TO 3 1

IF(LAST)9,9,10 - ;

GO TO 60 CONTINUE '

CALL E X I T

END

' " . <• APPENDIX 111 : ?

ISOTOPE EFFECT'S FOR THE IT IRE H ISOTOPIC AC 11") PAIRS RCTECOOil/RCDzCOOH, WHERE R = PhO,. CI, ANT) PhS,

CALCULATED BY THE S1EDEOVSKY III METHOD

PI1EN0XX5\CETIC ACID PAIR

CELL I

•~§iÇTj^^ - -..SiACjr^^ -isnroi'P-];PFPCT- '- -

370 . .0 .9515 + .0008 .9612 + •.0008 i. 1 .0104' + .0009 371 . .0 .9512 + . 0008 .9611 .0008 1 .0104 ± .0009

37 2. .0 .9512 ± .0008 .9611 ± , ooos 1 .0104 ± .0009

373.. .0 .9511 -t . 0008 .' ,9610 ± .0008 1 .0104 f .0009

374 . .0 ' • . 9511 ± . 0008 .9610 ± .0008 1 .0104 + .0009

37 5. ,0 .9510 ± . 0008 .9609 .0008 I .0104 t .0009

376 . ,0 .9510 + . 0008 . 9609 ± .1)008 . 1 .0104 ± .0009-577 . .0 • .9510 + . 0008 " .9608 .0008 1 .0105 ± .0009

578 . 0 . 9510 ± .0008 • • ,9608 ± ' .0008 1 .0103 .0009

579 . X) .9509 + . 0008 • ' .9607 ± .0008 1 . 0105 t .0009

580 . 0 . ' .9508 : 0008 .9607 .0008 1 .0104 + .0009 •

5 8 1 . 0 •'- .9508 ± .0005' .9607 ± . 0008 1. .0104 .0009

582 . 0 .9507 + ,0008 . .9606 .0008 1 .0104 ± .0009

585 . .9506 ± .0008 _ .9605 .0008 1 . 01 04 ± .0009

584 . 0 . .9506 ± . 00(18 .9605 .0008 I .0104 •i .0009

385.5T .9506 ± .0008 . 9 0 0 5 ' ± .0008 1 .0104 ± .0009 5 8 6 . 0 %.v v. 2950,5 + .0008 ^ 9 6 0 4 ± . OOOS 1. ,0104 . DO09

587 . 0 v -"5 9505 ± .0008 ' .9604 .0008 1, ,0104 ± .0009.

588 . 0 .9505 .0008 - ' .9604 .0008 1. ,0104 ± .0009

5 8 9 . 0 .9504 ± .0008 . .9605 ± . OOOS 1. ,0104 ± . 0008

590 . 0 .9504 + .0008 .9603 + .0008 1. 0104 t .OOOS

591 . .0 , . 9 5 0 4 .0008 ' ' .9605 i .0008 1 .0104 i .0008

5 9 2 . 0 . 9505 .0008 .9602 t .0008 1. ,0104 + .ooos •

5 9 3 . 0 . 9505 + .0008 .9602 + .0008 1. 0104 ± .0008 '

594 . 0 .9505 ± . OQOS .9602 ± .0008 I . 01 04 ± .0008

395 . 0 . .9502 .0008 • .9601 + .0008 1. .0104 + .OOOS

AV55RAGE ISOTOPE EFRICT = 1 .0104 ± .0009

\

, 2 5 4

..ha.. —StePl-mtClfl-r-l-O'' - ISOTOPE EEEECE

370 .0 .9514 + .•0008 .9608 + .0008 1.0098 + .0009 371 . o * .9515 .+ ' . 0008 .9608 + .0008 , 1.0099 ± .0009 572 . 0 .9515 ± .0008 :9608 ± .0008 1.0099 ± .0009 375, ,0 .9512.* .0008 .9607 + . 0008 1.0099 + . 0009

.574, . 0 , • .9512 ± .0008 .9607 .0008 1.0099 .0009 575, .0 .9.511 ± .0008 .9606 .0008 1.0099 ± . 0009 376 .0 .9511 ± ;ooos .9606 + '.0008 1.0099 t . 0009

0 .9 519 ± .0008 v .9605 ± .0008 1.0099 + . 0009 378, .9 510 .+ . 0008 .9605 '+ - -.ooos-- 1.0099 + . on 09 379. , 0 .'9 510 ± .0008 .9604 i . 0008 1.0098 + .0009-380, ,0 .9509 ± .0008 .9603-• ± .0008 1.0098 + .0008 581, ,0 9508 ± .0008 .9603 + ,0008 1.0099 .0008 3S2, , 0 \ .950S + .0008 .9603 ± .0008 1.0099 + .0008 585. 0 X.9508 ± .0008 . .9603 + .0008 1.0099 + .0008 384, .0 ',9 507' ± .0008 99602 ± .0008 1.0099 t .0008

-385-:0 • 19 507 "± TOOOS ' ~9"6"02~ + .ôp.os 1.0099 + . 0008 586, .0 • .9507 ± .0008 • •• ' .9602 .0008 1.0099 + . 0008 5S7. , 0 .f|506 ± .0008 .9601 + .0007 1.0099 + .0008 58S. 0 .92306 t .0008 .9601 ± . 0007 1 .0099- .0008 589. ,0 .9 506 ± .0008 .9601 + .0007 1.0099 + .0008 590. .0 .9505 ± .0008 - .9600 + .0007 , 1.0099, + .0008 591, .0 .951)5 ± .0008 .9600 + .0007 1.0099. ± . 0008 392. ,0 .9505 ± .0008 .9600 2 0007 1.0099 + . 0008 595. .0 . .950+ ± .0008 .9599 + .0007 1.0099 + .OOOS 594. 0 .95042 + .0008 .9599 + . 0007 • 1.0099 .0008 395. ,0 .9504 r± .0008 .9599 + .0007 1.0099 + .0008

AVTRAGE ISOTOPE EFFECT = 1.0099 + .0008

\

PHENQXYACETIC'ACID PAIR • -

CELL II

nJENOXTACFEIC ACIP PAIR

CELL III

— . - <**

siA)Pi;,nir(in x id- SLOPE,m t(T)) x in-- • ISOTOPl !-: ! EFFECT 37 0 .0 .9511 + . 0008 .9610 + .0008 1 .0104 -+ .0009 371 . 0 .9511 -t. -. 0008 ,%10 t . 0008 1 .0104 ± .0009 372 .0 .9510 ± .0008 • .9609 + .0008 1 .0104 + .0009 373 .0 .9510 ± .0008 ; .9609 t 5 0008 1 .0104 tt . 0009 5 "4 . 0 . 9509

>

+ .0008 . 96OS + .0008 1 .0104 i .0009 37 5 .0 .9509 + -.0008 . ..9608 + .0008 1 .0104 + .0000 57o JK ,•

.0 .9508 ± .0008 ' ,.9607 + .0008 1 .0104 + .0009 57o JK ,• .0 .9508 ± . 0008, . 9607 + . 0008 I .0104 ± . 0009 378 . 0 .9507. - ± . 0008 . 960 6 1 .0008 1 .0104 + . 0009 579 . 0 -.9507 .0008 ' . 9606 t .0008 1 .0104 + .0009 580 .0 .9506 ± .0008' ' • " ;9605 ± .0 48 \ .(1104 + .0009 581.. .0 " .9506 ± .0008 .9605 .0008 1 .0104 + .0009 582. . 0 .9505 ± .0008 .9604' .0003 1 .0104 + .0009 585. . 0 .9505 + .0008 .9004 + .0008 1 .0104 ' + .0009 ' .584. ,:o- '.9505- -v 00(18'——• — : 7 9 604- Tooos ~T. roioT Tooolf - ' 383. 0 .9504 + .0008 . 9005 + .0008 1 , .0104 + .0009 '380 . 01 .9504 ± 2 0008 .9003 ± .0008 1. .0104 + .0009 • 38". 0 .9504 + .0008 • .9603 .0008 1 . ,0104 + .0009 588. 0 . '.9503 + .0008 . 9602 ± .0008 1 . 0104 ± . 0009 389. 0 .9503 + .0008 . 9o02 .0008'. . 1 . 0104 * .0009. 590. 0' . .9503 .0008 .9602 + .0008 1 . 0)104 + .0009 591. 0' .9502 + .0008 .9601 + .0008 1. 0104 + . 0009 592. 0 .0.502 ± .0008 .9601 + .0008 1. 0104 + .0009 505. 0 .9502 + .0008 .9601 ± .0008 1. 0104; .0009 594. 0 .9501 ± .0007 .9600' ± . 0008 1. 0104 + . 0008 595. 0 .9501 + .OOO7 .9600 ± .0008 1 . 0104 + . OOOS

AWRAGE ISOTOPE - EFFECT = 1.0104 ± .0009

• . , . 25o

PIlbNOXTÀCETIC ACID PAIR

ŒLL IV

—~^f\^—'— -SbbiPI-rn r , . . r ,_ v _; ( , . ^S4:CPI^nrfCnj ::: bsToroïïiT"ï ; lier

370 0 .9512 t .0008 .9615 ± .0008 i .0108 + . 0009 371 • 0 . 95 11 + . 0008 .9615 .0008 i . 0 1 0 9 V . 0009 3"2 0 .951 1 + .0008 .9hl5 + OOOS i .0109 + .0009 373 0 .9510 .0008 .9614 + 0008 i .0109 + .0009 374 0 .9510 + .0008 .9614 + 0008 i .0109 + . 0009 37 S 0 .9509 . 0008 .9615 ± 0008 ! .01'09 + . 0009 370 0 .9509 + .0008 .9615 + 0008 1 .0109 .0009 3 77. 0 .9 50 S + ,0008 .9612 +- 0008 1 .0109 + .0009 378. 0 ,.9308 .0008 .9612 + 0008 1 A)l 09 .00(19 370. ' ..9508 + .0008 .9611 + 0008 1 .0108 + .0009 380. 0 .950" ± . 0008 .9611 + 0008 1 .0109 .0009 381. 0 ' .9 50 -J + . 0008 .9610 ± 0008 1 .0108 + .0009 382. 0 .9507 ± . 0008 . ' ' .9610 + 0008 1 .0108 + .0009 5S3. 0 • .9506 .0000 ' .9609 -t 0008 1 .01 08 .0009 584. o .9 500 ± '. 00 OS , .9609 ± 0008 1 01 08 + .0009

—585-o — - .950 5" -0007 ' '79609" "0008" 7)To1T + ToTfoTT 58b. 0 .9505 + .000" .9608 + 0008 1 0108 ± .0009 58" . 0 .9505 + .000" .9608 ± . 0008 1 010.8 .0009 588. •o .9502 + .0007 • .960" + 0008 1 0108 + .0009 389. 0 .9504 + .000" .9607 + 0008 1 0108 + .0009 590. 0 .9504 + .000" .960" ± . 0008 1 0108 t .0009 591 . 0 .9505 i .000" .9606 4- 0008 ^ 1 OÏ08 ± .11008 392. 0 '.9503' .000" '.9606 + 0008 ' b 0108 .0008 595. 0 .•9503 + .000" .9606 ± . 0008 . 1 0108 + .0008 394. 0 , .9502 + . 0007 .9605 t . 0008 1 . 01 OS + .0009 59.5. 0 -.9502 4 .000" .9605 ± . 0008 1. 0108 + . 0009

A\i2i2\cb [snroph ppFbcr = l.oios + .0009

: 257

i\n— —SLBPH-nr 2(D)- x-lOo •--ISOTOPE 1-iFFECT-370. n .9511 + .0008 - .9616 + .000° '1.0110 + .0009

\ 371.0 .9511 + .0008 .9615 + .0009 1.0109'. + .0009 572.0 .9511 ± .0008 .9615 .0009 ' 1 . 0109' + .0009 575.0 .9510 .0008 .9614 .0009 1.0109 + '.0009 57.1.0 .9510 +• v .0008 .9614 + .0009 , 1.0109 + . 0009 3v5.0 . 9509, ± .0008 . 9615

.9615 + .0009 1.0109 ± .0009

376.0 .9509 + •.ooos . 9615 .9615 + .0009 1.0109 ± .0009

.9509 ± .0008 ".9613 ± . 0009 1.0109 + .0009 5 7 SA 0 .9508 + . 0008 .9612 + .0009. 1.0109 +' .0009 379.0 .9508 + .0008 - •.9612 + .0009 ./i 'io.9 + .0009 580.0 .9507 ± .0008 .9611 + . 0009 1.0109 1 . 0009 381 .0 ". 950~ . 0008 .9611 .0009 - 1.0109 i .0009 552.0 '.'9506 + .0008 .9610 + . 0009 1.0109 ± . 0009 385.0 .9506 v.00O8 .9610' + .0009 1.0109 + . 0009 5S4.0

f .9505 + .0008 ' .9609 + . 0009 1.0109 + .0009

—585-.M1- T9505" T000S .9609 . 0009 1.0109 t .0009 3 8 Ô>.0 .9505 .0008 ' .9609 + .0009 1.0109 + . 0009 587.0 .9504 ± .0008 • .9608 + . 000.9 - 1.0109 i .0009 5SS.0 .9504 + .OOOS .9608 + .0009 1.0109 ± . 0009 589.0 .9505 + .0008 .9608 .0009 . 1.0110 t . 0009

^ioo.o .9505 + .0008 .9607. + , .0009 1.0109 + .0009 591.0 . 9503 + . 0008 .9607- + , , 0009 1.0109 i . 0009 592.0 .9502 + . 0008 .9606 .0009 • 1.0109 + .0009 595.0 .9502 + .ooos .9606 + .0009 1.0109 + . OOOP 594.0; .9501 ± .0008 .'9605 + . 0009' 1 .0109 * .0009 595.0 .9501 ± .0008 .9605 0009 1.0109 ±' . 0009

A\ TRACE ISOTOPE EFFECT •= 1.01O9 + .0000 • \

Pin.NOXYACF,TIC ACID PAIR

CPLL V •

25S

CIILOROACF.TIC ACID l'AIR CELL I

SLOPE .nifX 370.0 571.0 .572.0 575.0 574.0 575.0 5"6.0 577'. 0 578. 0 379. 0 580.0 3SI .0 5S2.0 385.0 5S4.0 585.0 5S6.0 587 .0 5SS.. 0 589.0 590. 0 591.0 592.0. 595.0 594.0 595.0

.,4726 +

.47 20 ±

.4725 .+

.4725 +

.4725 +

.4725 ±

.4724 ±

.47 24 t

.4724 t

.4:

.47 25 + '

.4725 +

.47 25 +

. 4722.c±_

.4722 ±

.4"22 ±

.47 22 ±

.4-21 T

.472] ±

.4721 ±

.4721 ±

.4721 f

.4720 ±

.4720 +

•0003 .4780 + .0003 .0003 . .4780 t .0005 .0005 • .4779 ± .0005. • .0003. •. . 4"779 f .0005 .0005 .4779 + .0005 '..0005 • .4778 ± '.0005 .'0005 .4778 + .0005 .0005 ' .4778 + .0005 .0005 •• .4778'+ .0005 .0005 .4 "8 + .0005 .0005 .4777 + .0005 .0005 .4777 + .0005 . .0005 .4 7~" + .0003 " .0005 :,4 777 ± .0003 .0005 '.4~77 ± 70003 . ..0005 ~. 47-76-+—. 0005 .0005 .4776 ± .0005 .0005 .4"7b ± .0005 -.0005 • .4776 + .0005 .0005 . , . 4775 + '.0005 .0005 .4775 + .0005 .0005 .4775 + '.0005 .0005 ' .477 5 +' .0005 .0005 . • .4774S+ .0003 .0005 .4774 + .0005 .0005 .4774 + .0005

-RS0TOPE—RrTTCT''

1.0114 ± 1.0114 ± 1.0114 ± 1.0114 + 1.0114 + 1.0112 + 1.0114 + 1.01.14 ± 1.0114' + 1.0114 ± 1.0114 ± 1.0114 + 1.0114 + 1.0114 2 l."fâl4 + -1- 01-14-+-1.0114 ± 1.0114 + 1.0114 + 1.0114 ± 1.0114 + 1.0114 + 1.0114 2 1.0112 + 1.0114 ± 1.0114 +

.0008

.0008

.0008

.0008-

.0008

.0008

.0008

.0008

.0008

.0008

.0008'

.000S

. 0008

.0008

.000 S

TO 008 .0008 .0008 . 0008 .0008 .0008 .0008 .0008 .0008 . 0008 .0008

AVERAGE ISOTOPE EEI2ECT = 1.0114 ,0008 >

259

Q1LOR0ACF.TIC ACID PAIR

ŒLL II

SLCOPE-mf-f-Dj-x-lO2— SOTO PI Tl EFFECT" 370.. 0 .4725 + .0005 • .4780 + .0005 1 .0116 ± . 0008 . 571 .0 .4725 + .0005 .4780 ± .0005 1 .0116 + .0008 372 . 0 .4725 + .0005 .4 780 + .0005 1 .0116 ± .0008 575 .0 ' .47*25 +•' .0005 .4780 ± .0005 ' 1 .0116 . OOOS 5 74 . 0 .-724 + . 0005 .4779 + .0005 1 .0116 ± .0008 575 . 0 . .4724 ± .0005 .4 779 + .0005 1 .0116 ± .0008

. 570 . 0 .4724, + -.0005 • .4779 + . 0003 1 .0116 + .0008 ' 577 . 0 . .472-. + .0005 .4779 ± .0005 1 .0116 t .0008 578 .0 .4" 25 + .0005 ' .47"S ± .0005 1 .0116 + .0008-5751 .0 .4723 ± .0005 .4778 ± .0003 . 1 .0116 .0008 580. .0 .4723 + .0005 , .4778 + .0005- 1 .0.116 + .0008 - 381. .0 24725 + .0005 ' .47"8 ± .0005 1 .011 6 + . OOOS 582. ,0 .4722 + .0005 • ..47-7 ± .0003 •• 1. .0116, + .0008 583. 0 .4722 i .0005 .477- ± .0005 ' 1 . .011.6? + .0008 5S4. 0 .4^22 + .0003 .4777 ± .0005 1. 0116 i .0008

_JL8.5-_0 4722_ - 0005 .-4777-+— 7 0005 - ] , . r0116-T TPOOS" 580. 0 .4722 ± .0005 ..4777 ± .0005 1. .0116 -t .0008 38". 0 .4722 ± . 0003 .47"6 ± .0003 1. 0114 + .0008 388. 0 .4722 '+ .0005 . .4776 + .0005 1. 0114 + .0008 5S9. 0 .4755 + .0005 _4 7~6 ± . 0005 1. 0114 + .0008 590. 0 .4722 ± ,.0005 .4776 + .0005 1. 0114 ± .OOOS 591. 0 - .4721 + .0005 - .4775 + .0003 1. 0114 + .0008 592. 0 .4721 + .0005 .4775 i •. .0005 1. 0114 ± .0008 595. 0 .4720 + .0005 .47"5 ± . .0005 ' 1. 0116 + . 0008 594. 0 .4720 + .0005' .4775 + , .0005 1. 0116 . 0008 595. 0 .4 720 + .0003 " .4774 ± . 0003 1. 0114 ± .0008

AVERAGE ISOTOPE EFFECT = 1.0TTÇ.+ .0008

1

260

570 .0 .4726 ± .0005 " .4780 + .0005 1 .0114 + ' .0008 571 .0 .4725 + ..0005- 2. .4780 + .0005 1 .0116 .0008 572 .0 .4725 + .0005 .4780 + A 0005 1 .0116 ± .0008 575 .0. .4725 + .0005 .4780 .0005 1 .01.16 + .0008 574 .(I .4725 ± .0005 .4780 + .0005 1 .0116 + .0008 575 .0 .4725 + . 0005 .4779 ± .0005 1 .0114 + .0008 576 .0- .4724 + .0005' .4779 + .0005 1 .0116 + -.0008 57 7 .0 .4724 + .0003 .4779 ± .0005' 1 .0116 + .0008 578, .0 .4^24 + .0005 .4"79 ± . 0005 1 .0116 ± .0008 579 .0. .4724 ± .0003 .4778 .0005 1 .0114 ± '.000S . 5S0, .0 .4725 + .0005 " .4778 ± .0005 1 .Olio + .0008 581. ,0 .4 72.5 ± .0005 .4778 .0005 1 .0116 ± -.0008 582. .0 .4725 + .0005 ,4778 ± .0005 1, .0116 + .0008 5S5. 0 .4725 + : 0005 -44777 ± .000.5 1. .0114' ± .0008 584. .0 • .47 22 + .0005' .4777 + ..0005 1. .0116 ± . 0008 '7585: c .

0

.4722 ± .0005 .4777 + .0005 I . ,0116 + .0008 ' 586. 0' .4 722 ± .0005 .4777' .0005 1 . 0116 + . 0008 587. 0 .4722 + .0005 . 4 7 7 7 + .0005 4 . 0116 ± .0008 588. 0 .4721 ± -.0005 .4776 + . 0005 •1. 0116 + .0008 589. 0 .4721 + .0005 .47-6' + . 0005 1. 014 6 + .0008 A590. 0 .4721 + .0005 .4776 + .0005 1. 0116 + .0008 591 . .4721 + .0005 !4776 + - .0005 1. 0116 + .0008 392. 0 .47 20 + .0005 .4775 + .0005 . 1. 0116 + .0008 .595. 0 .4720 + .0005 .4775 + .0003 1. 0116 ± .0008 7594. 0 . 4 7 20 + .0005 .4775- + .0005 1 . 0116 + . 0008 395. 0 .4720 i .0005 .4775 + 10005 . 1. 0116 ± .0008

. AVT.RAGE ISOTOPE EFFECT = 1.0116 2 .0008

4

'a-?LOROACETIC ACID' PAIR

CELL III

~:T'T. ! : i'li: x -1Q-- - SLOPE,mtQlj x 102 .: ISOTOPE EFFECT

26 1

QILOROACETIC ACID PAIR

CELL IV . .

~~^2o. ' ^KiPE^CflJ.' x IT) ;•- - - - SLOPE-,mt(D).- x 1(A - ISOTOPE ' EFFECT u 570 .0 .4727 . 0005 .4 781 + .0005 1.0114 + .0008

571 .0 . 4 7 2 7 ± .0003 .4781 + . 0003 1.0114 .0008 572 .0 .4727 + '.0005 .4781 + .0005 1.0114 ± A) 008 575 . 0 .4727 + .0005 .4781 + .0005 1.0114 + .0008 374 . 0 .4726 + .0003 . . .4780 + . 000.3 1.0114 + .0008 575 . 0 ' .4726 + .0005 .4780 + .0005 1 .0114 + .0008' 5 70 .0 . .4 726 + .0005 .47S0 + .0005 1.0114 ± .0008 '37 7 -.0 .4726 + .0005 .4780 + .0005 1.0114 + . 0008' 5 AS . 0 .4725 + .0005 .4779 ± .0005 1.0114 .0008' 379 . o .4725 ± - :0005- .4779 + .0003 •' 1.0114 + .0008 380 . 0 .4" 25 + '.0005 .4779 + .0005 1.0114 + .0008 581 , . 0 . .4"27 ± .0(105 .4779 .0005' 1.0114 + .0008 582. ' (1 .4725 + .0005 .4779 + .000.5 1.0114 + .0008 3S5. 0 .4724 + .0005' .47-8 + .000.5 1.0114 + .0008 584. 0 .4724 + .0005 .4778 + .0005 _ 1.0114 + ' .0008

-T'"3 S 57 -n—• '• 7472~4~ + 700075" .4778 ± .0005 1.0114 + s .0008 586. o . .4"24 ± .0005 .477S .0005_ 1.0114 + . 0008 587". 0 .4725 ± .0003 .4777 + .0005 1.0114 + .0008 588. 0 .47 25 ± .0005 .47"7. ± .0005 1 A1114 ± , .0008 589. 0 .4725 + .0005 .4777 + .0005 1.0114 + ,0008 • 890. 0 .4725' + .01)05 .4777 ± .0005 1.0114 + 00 OS 591. 0 .4722 ± . . 0005 .477o + .0005 1.0114 + 0008 592. 0 .. .4722 , 0005 .4776 ± .0005 . 1.0114 + 0008 32E5. 0 .4772 + . ,0005 .4776 + .0005 1.0114 + 0008

. 594. 0 .4722 ± . 0005 .4776 + .0005 4.0114 + 0008 595. 9 .4722 ± . 0005 .4776 .0005' 1.0114 + 000s

AVERAGE ISOTOPE IT7FECT = 1.0114 + ,0008

- 4 Cj'nOROAŒTIC AC IP PAIR

CELL V

•'i S LOPE, m t .(JiO_x_li)i_J SLCa^,m t-C^—^"J- -1SQTOR&-ËFFEGE 570.0 .4724 + .0005 .4782 + .0005 1.0116 + .0008

571.0 .4727 ± :0005 .4782 ± .0005 1.0116 + .0008 572.0 .4726 + ,0005 . ' .4781 + .0005 1.0116 +. .0008 575.0 .4726 t .0005 .4781 + .0005 1*0116 ± .0008 574.0 .4726 + .0005 A .4781 + .0005 U0116 ± .0008 575.0 .4726+ .0005 . .4781+ .0005 •• liftllôt .OOOS 576.0' • .4725 + .0005 .4780 + .0005 1. (Tj%fc ± .0008 577.0 •• .4 725 + .0005 .4780 + .0005 1.0116 ± .0008 578.0 .-4725 +'.0005 " - .4780 ± .0005 1 ,0116 + .0008 570. IP ,4/25 + .0005 .4780 t .0005 1.0116 + .0008 3S0.0 .4725 + .0005 .4780 ± .0005 1.0116 ± .0008 5S1.0 .4"24 + .0005 .4779 +, .0005 1.0116 ± .0008 582.0 .4724 + .0005 .4779 ±. .0005 1.0116 + .0008 Ô83.0 .4724 ± .0005 .4779 +_ .0005 1.0116 + .0008 5S4.0 .4724 + .0005 ' ,AN79 ± .0005 '1.0116 ± .OOOS _5S.5.._0. ._4225„+_.0005 , A7578_+-,-. 0005— l-.-Ol-16-t-; 0008-586.0 .4725 ± .0003' .4778 + .0005 ' 1.0116 ± .OOOS 5S7.0 .4725_+ .0005 .4~-S + .0005 1.0116 + .0008 588.0 .4725 + .0005 .4778 ± .0005 1.0116 ± .0008 389.0 .4723 t .0003 .477S. ± A 0003 1.0116 + .0008 390.0 ."4722 + .0005 .47"77 + .0005 1.0116 + .0008 591.(4 .4722 + .0005 .4777 + .0005 1.0116 ± .0008 592.0 .4722 + .0005 .4777 + .0003 1.0116 + .0008 593.0 .4722 + .0005 '.4777 + .0005 ' 1.0ÎL16 + .0008 594.0 -.4721 + .0005 .4776 ± '<0005' 1.0116 + .0008 395.0 .4721 + .0003 .4776 + .0005 1.0116 + .0008

A\TRACE ISOTOPE EFFECT = 1.0116 + .0008

265

- SWPB,mt(H) x 10 SïjOPE ,mt (DT x 10 ISOTOPE EFFECT" 370.n . 2465 + .0001 •• .2515 ± .0001 ' 1 .0202 + . 0006 571.0 .2464 + .0001 .2515 + .0001 ' 1 .0206' + .0006 372.0 .2464 + .0001 .2515 + .0001 E'! 020)6 + .0006 •575. 0 .2464 ± .0001 .2515 + .0001 1 .0206 + .0006 574.0 . 2464 t .0001 .2515 .0001 1 .0206 + .0006 575.0 .2464 + .0001 .2515 + .0001 1. .0206 + .0006 376.0 . 2464 + .0001' .2515 + .0001 1 .0206 ± .0006 577.0 .2464 + .0001 ' .-2515 + .0001' 1 .0206 + .0006• 378.0 . 2464 + .0001 .2515 + .0001 . 1 .0206 + .0006' 379.0 .2464 + .0001 .2515 + .0001 1 .0206 + .0006; 380.0 . 2463 + .0001 .2514 • + .0001 1 .0207 + .0006 381,0 ' .2465 + .0001 .2514 + .0001 . 1 .0207 1 .0006 382.0 . 2465 + .0001 .2514 + .0001 1. .0207 ± .0006 385.0 • .2463 + .0001 : .2514 + .0001 • 1. .0207 ± .0006i

584.0. ,.2463 + .0001o * .2514 + .0001 ..Q2.Ô7_ Jr__ .0006. 585.0 .2463 + ,0001 .2514 + .0001 1. ,0207\ ' .0006 386.0, . 2465 + ,0001 .2514 + .0001 1. .0207 .0006 387.0 ' ' .2465 + 0001 .•2514 +. .0001 1. ,0207 ± .0006 388.0 .246 5 + . "oooi .2514 •+ .0001 1. ,0207 + .0006 389.0 .2463 + . 0001 .2515 + . 0001 1. 02Q3 + . oV)6 590.0 .2462 + 0001 , .2515 •t .0001 1. 0207 .Oof 6 391.0 .2462 + OD01-- - h i .2515 ± .0001 1. 0207. ..0006 592.0 . 2462 ± . 0001 .2515 + .0001 1. 0207 + .0006-393.0' .2462 + 0001 ' .2513 + .0001 1. 0207- ± . .0006 • 394.0 ' .2462 + 0001 ; .2513 + ."0001 1. 0207 + 395.0 . * .2462 + 0001 .2 513 + .0001 • 1. 0207 + ,0006.

A\TRAGE ISTOTOPE'ElTECff = 1.0207 + .0006

> - o

PIlFlTailllOGLYCQLLIC ACID PAIR

CELL I

PHCNYLTinQGLYCOLLIC AC ID PAIR CELL II

- -•- - ,1 --- -32f.. """ SLOrEJmt(!n""-x 10' SLOPE,mt[RJ x 10 ISOTOPI -; 1 :EEECE

370.0 .2404 .0001 .2515 + .0001 •1 1206 •+ . 0006 571.0 .2464 + .0001 ' • .2515 .0001 •• - 'l"3)206 -+ .0006 372.0. .2464 .0001 , .2515 ± .0001 1 .0206 t .0006 57 5..0 £m . .2463 ± .0001 .2515 ± .0001 '1.0211 + .0006 571.0 " .2403 2 .0001 .2515 + . 0001 • 1.0211 + -.0006 575.0 .2463 4-, .0001 -.2515 .0001 1.0211 ± .0006 376.0 . 24<Ç5 ±. .0001 .2515 ± . 0001 1.021Î .0006

-; 37770 • .2463 i .0001 ' ' .2515 i .0001 1.0211 + .0006 '•375.0 » . 2465 + . 0001 .2514 + .0001 1.0207 i- .0006 E7 O;_0 .2465 .0001- ' .2514' + .0001 " 1.0207 + .0006

. 2465; ± .1)001 • .2514 + . oo2ôT~ 7" 1.0.207 f . 0006 581 .()" - .2465 + .0001 .2514 .0001 " 1.0207 f .0006 582.0 .246 2 . 0001 _ .2514 .0001 1 .0211 + " .0006 78 5. /').

_ 3 S l l(l_ .2462 + ,0001- .2514 + .0001 - ' 1 .0211 t .0006 78 5. /').

_ 3 S l l(l_ ,..2462,- .0001 .72-514-- t— -0001" lV021ir TO'0'0'6" 3S5.0; '.2462 .00.01 '.2514 + 000] ' ~ 1 .0211 + .0066 3 S G .0 - .2462 .0001'. . " 2514 + 0001 1.0211 . 0006 58". 0 -• ' .2462 .0001 / -.2514 0001 - 1,0211 -t . 0006 38870 • .2462, + 0001 '•- . .2513 + 0001 1.02T>7 i .0006 5S0.0 • . 2462 + 0001 • -' . : zs i s + 0001 ' 1.0207 -t .0006 590.-0 .246 2 0001 ; 25r + • 0001 1 472207 ± .-0006 ,50 j . 0 '. .2462 + 0.001 > v 2 5 r + , 000] 1.020 .0(i06. 392.0 •

.2462 + 000! - 7 + 0001 1 .0 20^ + .0)006 39.5. 0' ! 2462 + •6001 .2515 + 0001 ' 1,0207 + 0)006 .594.0 • .2461 + Of) 01 _ .25.15 . + 0.001' l\0211 •+ .0006 595.0 • .2461 00 01 .2515 0001 1.0211 .'0006 .

AVERAGE [SOTOPE EEEECI '= 1.0309 + '.0006

, 0 V

'v, •" PHI-NTLrn MOGLYCOLLI C AC 1D PÀIR A , ŒLL III'

~~I:0PG> rrr>T"io-- SLOPP,m "x. 10 •' " ' • 1 SOTOPI 1 PPIT.CT 5 70 . 0 ''•A 2404 + ,0001 • .2515 4 0001 1 .0200 + .0006 ' 371 .0 ' '\,.2464 + .0001 .2515 4 0001 1 .0206 i .0006 57 2 0 22464 + '.0001 .2515 4' 0001 1 .0206 .0006 573 0 .2464 4 .0001 .2514 4- 0001 1 .0202 .'.0006 374 0 .2464 t .0001 ' ' .2514 + 0001 I .0302 + .0006 575 0 . .2464 + .000] • .^^A2514 4 0001 . 1 .0202. •t . 0006 370 0 . 2464 + .rtOOl , (2514 t 000] 1 .0202 4 .0006 • ' .577 .0 .2405 4 .000] ••" .2514 t . 0001 • 1 .0207 ± .000.6 37S 0. .2463 4 .0001 ' .2514 t . 00(1] . i .0207 + .0006 570 0 .2465 4 .0001 .2514 ± . 0001 1 . 0207 4- .00(10 '380. 0 .246.3 4- .0001 .2514 4 0001 r 0207 4 .0006 .581'. (1 -.2465 t .60(0 .2514 t 0001 1 0207 + .0006;,. • 582. 0 . . 2465" 4 .. 0001 .2513 4 000] 'l 0203 ' .0006 585. 0 .2465 i -.0001 . • .2513 t . 0001 1 0205 4 .0006 584. 0 . 246.3 4 .0001 . .2513 0001. ' J., 0205- mVi6-—

1.0207 t .0006 1.0207' + .0006 1 .0207 + .0006 1 .O207 t .0006 1.020" t .0006 1 .()2()7 t .0006 1 .0 203 i . 0006 1.0203 t . 0 0 0 6

0006 T, 0203 Î .0006 .

v 1 ,0203 t - 01)0(1

-38 5 5 S 6 387 •388 380' 500 91 302 505 594 595

r0-.0 . 0 .0 . o .0 . 0 . (I , 0 .0_ .0

•72462 t .0001 .2462 + .0001

,2513Jt .OOAl .2513 + .OOÏTî'

.WTV.XÙl jSOJOPP PPPLC!' - J , 02').' t ,0009

2 6 6

PlEA'j;nlJOGLYCOLLJ,C^CID PAIR'-.

CELL I V .

, , .——1 r^rr - '—=——

-.- - h0 SLOP£y»v(Hj - X-10- - vSI/JPF,->mt-(Dj"X---10 KSOTQPE ' EFFECT " 3 7 0 0 . 2 4 6 4 + . 0 0 0 1 ' . 2 5 1 6 + . 0 0 0 2 1 . 0 2 1 1 + . 0 0 0 7

3 7 ] 0 . 2 4 6 4 + . 0 0 0 1 . 2 5 1 6 + . 0 0 0 2 1 . 0 2 1 1 +• . 0 0 0 7

3 7 2 0 . 2 4 6 4 + , . 0 0 0 1 . 7 5 1 6 + . 0 0 0 2 1 . 0 2 1 1 + . 0 0 0 7

5 7 3 0 . 2 4 6 4 + . 0 0 0 1 . 2 5 1 6 ± . 0 0 0 2 1 . 0 2 1 1 + '. 0 0 0 7

. 3 7 4 0 . 2 4 6 4 + . 0 0 0 1 . 2 5 1 6 + . 0 0 0 2 ' 1 . 0 2 1 ] + . 0 0 0 7

5 7 5 0 . ' 2 2 4 6 4 + . 0 0 0 1 - ,v - .2 5 1 6 + . 0 0 0 2 1 . 0 2 1 1 ± . 0 0 0 7

3 7 6 0 . 2 4 6 4 ± . onoi . 2 5 1 6 -+ . 0 0 0 2 1 . 0 2 1 1 4- . 0 0 0 7

5 7 7 0 . 2 4 6 5 ± . 0 0 0 1 . 2 5 1 6 + . 0 0 0 1 . . 1 0 2 1 5 + . 0 0 0 7

3 7 S • 0 . 2 4 6 3 . 0 0 0 1 . 2 5 1 6 . 0 0 0 1 4 . 0 2 1 5 + . 1 ) 0 0 7

, 3 7 9 0 * . 2 4 6 5 + . 0 0 0 1 . . 2 5 1 5 + . 0 0 0 1 •1 0 2 1 1 ± . 0 0 0 7

3 80 0 . 2 4 6 5 + . 0 0 0 ] . 2 5 1 5 . .oooT • 1 0 2 1 1 '+ . 0 0 / 0 7

5 8 1 0 . 2 4 6 5 + . 0 0 0 1 ' . 2 5 1 5 . 0 0 0 1 1 0 2 1 1 it . 0 0 0 7

5 8 2 0 . 2 4 6 3 .oooi • . 2 5 1 5 ± . 0 0 0 1 " 1 0 2 1 1 t . 0 0 0 7

5 8 5 0 . 2 4 6 5 ± . 0 0 0 1 . . 2 5 1 5 ± . 0 0 0 1 1 0 2 1 1 ' + . 0 0 0 7

5 8 4 0 ' . 2 4 6 5 + . 0 0 0 1 . 2 5 1 5 + . 0 0 0 1 1 0 2 1 1 + . 0 0 0 7

5 8 3 0 . 2 4 6 5 t . no oi . 2 5 1 5 + . 0 0 0 1 1 0 2 1 1 + . 001") 7

' 5 8 6 0 ' . 2 4 6 5 ± .oooi . 2 5 1 5 + . 0 0 0 1 1 0 2 1 1 f . 0 0 0 \ 7

. 5 8 7 0 . 2 4 6 2 + . 0 0 0 1 2 5 1 5 + . 0 0 0 1 1 0 2 1 5 ' i . 0 0 0 7 *

5 8 S 0 . 2 4 6 2 t . 0 0 0 1 - • . 2 5 1 5 + . 0 0 0 1 1 0 2 1 5 t . 0 0 0 "

3 8 9 - 0 . 2 4 6 2 + . 0 0 0 1 • . 2 5 1 4 + . 0 0 0 1 - . 1 0 2 1 1 + . " 0 0 0 7

5 9 0 0 . 2 4 6 2 + . 0 0 0 1 . 2 5 1 4 + . 0 0 0 1 1 0 3 1 1 + . • 0 0 0 7

' t 5 9 ] 0 . 2 4 6 2 . 0 0 4 1 • , 2 5 1 4 + . 0 0 0 1 1 0 2 1 1 + . 0 0 0 7

5 9 2 0 . 2 4 6 2 .oooi - . 2 5 1 4 + . 0 0 0 1 1 1 6 2 1 ] . 0 0 0 7

5 9 5 - . 0 '. 2 4 6 2 ; . 2 5 1 4 + .oooi 1 0 2 1 1 ± . 0 0 0 7

3 9 4 0 . 2 4 6 2 " ± . 0 0 0 1 . 2 5 1 4 + . 0 0 0 1 1 0 2 1 1 ' ± . 0 0 0 7

5 9 5 0 ' . 2 4 6 2 + . 0 0 0 1 . 2 5 1 4 ± . 0 0 0 1 1 , 0 2 1 1 i ' . 0 0 0 7

AVTimCE E S r r r O P E E F F E C T - . 1 . 0 2 1 ] ± 2 0 0 0 7

\

V 2(f

THENTLTHIOGLYCOLLlC AGI]) PAIR CELL V

tCH-: tCH-: ~>T"10 570 .0 .2404 + •0001 . 571 .0 • . .-2464 0001 , ;

572 .0 • "464 575 .0 .2464 \'+ 0001.4

574 .0 .2464 0001 ^ 7v 5 . 0 *' .2464 ± OOORAA; 576 .0 • .2464 •+ 00OR.|i

. 0 .2463 0001 ; 378 .0 . 2463 .0001 ' 579 .o- •• .2465 ± 0001 380 0 - .2463 + • 0001 ' 581 .0 .2463 ± 0001 582 .0 ' .2463 + 0001 5S5 0 .2463 ± 0001 584 0 .2463 ± . oooi

A385-~0 — — 7 2 4 6 3 ~+—; "0001 586 0 .2463 0001 587 0 .2462 + 0001 588 0 ' .2462 + . 0001 589 0 . .2462 ± . 0001 390 0 . 2462 0001 591 0 . 2462 0001 592 o .2462 + o'ooi • 393 11 .2462 0001 394 0 . 2462 + 0001 395 0 .2462 + 0001

',:A''0,";.25i6. t' --..oooi i^^A'2516'tl 001 *AAr . ;C:A'5JA > '' .. f5i6'-t; pi ik : i'^4i^^o^i w& '

1^&0C.-'. 0001 Y2516 +".0001 . 72 515 '+ .0001 '* .72 3,15.+'- .000] .2515 + .00OR .2 515 V .OOoi • .2515 + .0001

"T2'51A5'"ï~T'00Or"

.2515 t .0101

.2515 ± .0001

.2515 i .0001

.2514 + .0001" 2 514 t -.000] , .2514 + .0001 .2514 ± 70001 .2514. ± .0001 ,2514 ± .0001 . 2514 + .0001

ISOTOPE- EFI-ECP 1.0211 1.0211 1.0211.

. 1.0.211 1.0211 '1.0211 1.021].' •1.021 5. 1 .0215 1.0215 1.0211 1.0211 r. 0211 1.0211 1.0211 TToTiT 1.0211 1.0215 1.0215 1.0211 1.0211 1.0211 1.0211 1.0211 1.0211 1.0211

± .0006 t .0006 ± .0006 ± .0006 + .0006 ± .0 006

± .0005 ± -.0006 + .0006-± .0006 + .0006 ± .0005 ± .0006 •t .0006

i .10006 + .0006 i .0006 + .OOOo t .(."1000 t .0006 + .0006 + .0006 + .0006 1 .0006

A\5ERAGE ISOTOPP EEFECr = 1.0211-± .0006

L APPENDIX TV • 0 : —

ABBRIlVlATED, mLSULTS OF THE SHEDli/)VSKY IV TRTiATMENT OF CONCENTRAT I ON -'FQU] VALENT fflNllJCTANCE DATA OF PhS02CH2COOEl ' AND THE: LSOTOPICyvLLY SUBSTI TILTED- ACETIC ACID FAIRS

• ' Rai?Cœi[/RCD2COOH, M IE RE R >hO, Cl, AND PES

A X

4-, . CELL I

.,579.0' .56.98 t .1802 579.1 56.95 + .1695 579.'2 . - 56. SS ± .1600

379.5. ' 56.85 t .1521 579.4 56.78 + .1458. 379. 5 . '5.6. 73 ± . 1414 7579.6 '' 36.68 ± .1591 579.7 36.65 + .158" 579.8 .56.58'+ .140" 379.9 56.55 ± .1445 580.0 ' 56.48 ± .1501 580.1 • 56.44 + .1572 5SD-. 2 56.59 + .1656 580.5' 56.54' ± . 1754 580.4 36.29 t .18 59

P1IE2N4LSlILF0:-E4^CETIC ACID

• \ j (AIT.RAGE K t ± c.) x 10"

CELL II CELL 111 ' CTLLxlV i . :

56.98 t .1746 56.98 + .1740 56.98 ± .1805 ! ' ?

56.95 + . 1 6 4 5 ' 56.95 +..1651 ' 36.95 + .1697 56.88 ± .1555" ' 56.SS - .1554 56.88 + .1601

! 56.85 t .1479 56.85 ± .1454 36.83' ± .1521 56.78 + .1422 - 56.78 + .1590 56.7S + .1458 i i

56.7.5 ,± .1587 56.74 * .1,546 56.75 t .1415 36.69"+ .1571 36.69 t .1325 36.'68 t .1389 36.64..+ .1578 ' 56.64 + .1324 , 36.65 + .15S5 36.59 + .1404 56.59 + .1546 . 36..5S .+ , 1403 .36.54 + . 1-45(1 56.54 +_.15SS 56.55 ± .1440. 56.49 t .1514 56.49 ± .1448 56.49+ .1496 56.44+ .1592 56.44 t .1524- .36.44 ± .1567

i

36.59 t .1685 56.59 +._J£15 56.59 ± .1651 '• * * ' 56.54 ±. . 1-785 36.55 + .1715 36.54 + .1749

" - I 36.30 + .1894 36.50 + .1825 56.29 + .1855

CELL

36.98 + 56.95 1 56.88 • + 56.85 + 3<j./7S +

56.75' + "36.68 t

.36.63 t

36.58 i

- 56.5.3 + .56.48 ±

^.36.45 t 56.39 t 36.54 + 56.29 ±

V . ' .1801 .1696 .1602 .1526 .1465 .1425 .1403 .1402 .1422 .1462 .1519 .1592 .1677 .1775 .4 880

PIN^NOXTACETIC ACID

(AVT.R.AGE Kt t 6)' x- 10/

pell i

75.28.+ .1818

E5.21 + .1702 J3.15 ± .1713

73.09 + .16 2

A3.02 .± .1640

'2.96 + .1617

"2.90 t .1604

'2.84 t .1600-

'2777 t .1607:

'2.71 t .1622

•2.65 t ; 1647 r2.59 + .1681

'2.52 + ; 1721 72.46 ± .1770

"2*.'.40 + ... 1825

CELL II I

7.5.26 + .1801 "!

75.20 ± .1744 i

' •' I . 75.14 +' .1695

. • 1" •73.07 + .1654

I ' 75.01 t .1622

' 72.95 + .1599 I

• 72.89 ± .1586 i

72.82, ± .1582 &- 72.76 + .1589

722*. 70 + .1645

72.64 + .1650

- 72.57 + .4664 • " ..I 72.51 + .1704

7 2.4 5 + .1755 1

?2.59 ± .1810

CELL III

75.28 ± .1788

7,5.22 + .1755.

73.15.+ .1686

.75.09 + .1648

73.03 + .1618

722.96 + .1598

72.90 + .1587

72.84 + .1585

72.78 + .1595

72.71 •+ .1615

72.65 ± .1641

72.59 2 .1676

72.55.+ .1720

72.46 ± .1771

72.40 + .1S29

CELL IV.

45.29 + .1796

75.22 + .1752

75.16 + .1676.

75.10 ± .1627

7 5.04 ± .1587

72.97 + .1557

72.S5 ± .1525

72.7S + .1525

72.72 t .1552

72.66 ± .1551

72.60 + .1579

72.54 ± .1616

CEUU V

,xi.Z/ t

75.21 t

75.14 ±1

75.08 +;

75.02 .+.:

72.95 + E91 ± .1556 72.89 + •

1704

1658

1622

!1599

1576

1567

72.85 ±2-4568

72.77 +

72.70 +

•72.64 +:

72.58 ±

1580

1601

1651

1668

52 + ;.R715

72.47 + -.1662 72.45-1 .Afl767

72.41 + .1715 72739 f .:.1826

ŒLL I

:-.7n ± .-183P-

ŒLL ill

PIENOXTACET] C-2 ,2 -d 2 ACID

CELE III

Al + . 1820

"D .4 ;AA2264:-^

379;S'-\~^2;58 *;:.1728 «*N72.58 ' " " ' '" c-'-A7 •-379.6

5"9. 7

379.8

379.-9

380.0

380.1

5S0.2

' .580. 3

380.4

580.5

5S0.6

380. f

p...v-Ç.s ;_ AC '"2.4 5 ± .1657"

72.39 k .1635

72.331 .1622

72.27" + 1619

72.20 + .1625

752.14.+ -1641

72.08-+ .1665

72..02 + .1697

71.96 t .1736 7].90 t .1783 _1.S3'+ .1838

1771

1 7 5 0

-72.52 + .169" i ! 72.46 ± .1673 r

" t. 72.39 + .1657

, I

72.33 i .1651

72.27 + . 16'S5

72.21 + .1667" 72.15 t. Î6S9'

'1 72.OS + .3 718

. i 72.02 + .1755

• 1 71 .'Q6 + .1799

! • 71.90 ± .1850

- 1 "1.84 + .190"

7 ?

72

''•71

71

71

.65 t

.59 +

,A •47 t

. 40 +

. 34 t

.28 ±

. 22' +•

,15 -t . 09 ±

.05;+:

297 +

91 t

85 -+

CELL

.1810

.1757

.1711

.1675

.'1645

.1624

.1613

.1612

.1620

.1637

.1663

..169>7j43^2^03 ±

7"17'37 '^te57X±' ''''

.1787 ' -7l .91 '

.1843 71.85 ±

72.65 i

72.59 t

7 2.53 +

72.47,+

72.40 +

72.34 +

72.28 +

72.22 +

72.15 +

52,;.,Q9 +

1984

1921'

1865

1816

1774

1741

1717

1700

1692 •

1695

1703.

1721

1748

1785

1825,

. CELLS V

;2,52 t

t .1986

c .1929 + " .1879 + 1836 + ; 1S01 + 1774--± ;

'

1756 i , .1745 + ; ,1744

± ~ .1751' + ! . 1766

72.02 + 71790 •il

71.96-+ 71821 .il'-

71.90.-+ 11S60 I

71.83 t .1906

es.

QÎLOROACETIC ACID (.WTMŒ'Kf' t- ÔJ x 10s

0

•) CELL 1 . CELL Î1I i |

TEL], III CELL TV CEI L V' 389 4 140 5 5864 140 5 + 5966 •1 .140 .5 4 .•5865 140 5 4 4017 140 5 .5998 589 5 140 5 + , 5755 „ 140 '4 ± 3S60 1 1

140 .4 + . 3750 140 5 4 .5900. 140 4 + . 5884 589 6 140 n 5660 140 i + 1

3770 . 140 4 .3647 140 2 + 3796 - 140 . 4 .3782 589 7 140 1 + .

/ 5582 140 1 + 5695 140 .1. 4 .3562 140 1-+ 5708 140' 1 + .5697

589 8 140 (J +- . 5522 140 0 + 5658 4 140 .0 4 .3495 -. 140 0 + 3656 140 0 .3629 5589 9 159 S + , 5477' 159 9 [ 5597 " | 139 . o 4 .3444 .•139 S 4 5580 159 9 ;. 3576 590 0 159 7 5456 ' 159 7 + i

5576 139 _ 7 4 -.3412 139 7 4 5545 159 7 '+ .3542 590 1 159 6 544 5 1759 6 t 5574 | 139 6 4 .3599 . 159 6 + 5521 159. 6 72 ..5523 590 9

5 159 S + 54 59 159 % V L 5587 | 139 . 5 4 .3407 . 159' 5 + 5522 "159 5 + .3527

590

9

5 159 4 5489 159 4 4- 1 5618 | 139 .4 + .5455 . 159 4 4 5540 159 4 + .554S 390 4 159 5557 5 .159 7 '+ 3665 i 139 .2 4 .3475 159 ± 25574 159 •± . 55S4 590 5 159 1 5601 159 l + 1

3730 -\

139 .1 4 .5555 159 i 4 .5625 159 1 ± .. 5659 390 6 .139 0 5685 159 0 +

1 3812 ] 139 .0 4 .3612 159 0 4 5694 159 0 + .5710 590" 7 138 9 + 57 80 158 9 + 1

3905 13S ,9 + .3704 15S 9 + 577 5 158 Q + .3.796 590' 8 158 4- 5886 158 7 4

1 4014 13S S ± .3S09 13S 7 + 58 74 15S 7 4- .5895

7 590.4

.5

.6

1262

1017

Ap ' " CELL I

589.9 15S.5 2 .2045

590.0 138 71 + .1776

390.1 13S.0 ± .1515

590.2 ,.137.9

137.8'

157.6 + .0794

137.5 i .0611

590.6 157.4 + .05516

590.7 15". 5. i .08 54

590.8 " 157 .1+ .0697

590.9 157.0 t. .0901

591.0 156.9 t .1129

591.1 ; 156.8 ± .L372

591.2 156.6 + .1620

591.5 156.5 ± .1875

g-tLOROACETT C - 2,2 - d 2 ACID;

, (AYTRA67E K't '-t* 3) x 105

CELL

158.5 .+

158.1 ±

158.0 +

I.57.9 ±

157.8 +

137.6 ±

157.5 t

157.4 t

137f.3 +

157.1 t

157 . 0 +

156.9 +

15648 +

156.6 t .

156.5 ±

I

J2118 .Î1852 .1595 I

. 1 5 4 5

.110 5

.0884 i .07)0 1 .0595 1 •I .0601 i

.0714 i . .0898 i .1114 .1549 1 !

.1591 1

.1S59

CELL III

158.3 +

158.1 ±

158 .0 +

157.9 +

1*37.8 t

157".6 i

157.5 +

157.4 ±.

157.5 +

.157.1 +

157.0 +

156.9 +

•156.8 +

156.6 +

156.5 +

.2187

.1020

.1658

.1404

• 1157

. 0928

.0724

.0585

.0555

.0641

.0816

.1027

. 1262

.1505

.1755

CELL IV

158.2 f .2556

158.1,+ .2064

-15S.0 + .1794

157 9 t .1527

157.7 t .1265

157.6 2 7 001

157.5 ± .0755

157.4 t 51529

157.2 +' .0571

7 57.1 t .0579

157.0' 2 .0541

156.9 t ,0764

156.7 ± .1008

156.6 + .1206

156.5' t .1516

CELE Y

'158.27 .2526

1 5 8 . 1

•1 2 0 5 6

1 5 8 . 0 4 . 1 7 9 1

15.7.9 jl

137. 7 r±

157.6 1'

157.5 +

157.4 ±

157.2 +

157.1 *

157.0 +

136.9 i

156.7'+

136.6 i

156.5 +

.1529

.1274

.1027

.0799

.0605

.0500

.0524

.0665

.0869

. 1E00

.1342

.1589

380.6

5S0. ~

380.8

5S0.9

582.0

581.1

581.2

5S1.3

381.4

581.5

581.6

381.7

581.8

381.9."

582.0

PI LENA LIU 1OGLY COLLI C. AC IP

(AWRACJ. K t + 6J x 10E

CELL 1

281.1 + 3450

'280.9 + .4441

280."" ± .4382

280.5 + .435"

280.3 ± .'4296

280.1 t .4273

279.9 i .4259

279.8 i .4255

279.6 + _ .4265

2279.4 t .4278

279.2 + .4308

279.® t .4349

278.8 t .4400

278.6-f .4457

278.4 + .4525

CELL!n

281.1 ± !4443

28029 + ,4593 j

280.7 + J4356

280.5 t J4350

280.5 + J4 514

280.1 ± J4307

279.9 + J4314 279.8 +

279.6 ±

4331

,4360 I A

^ .279.4 + .4396

.279.2 + .|l442 1

279.0 + .4500

.. 278.8 1 .4568

2787 6 ± .4644 I

278.4 + ..4724

CELL III

281.1 4 .4439

280.9 ± .4571

280.7 ± .4317

280.5 ± .4271

280.5 + .4236

280'.2 t" .4212

280.0 + -4200

279.8 + .4199

279.6 + .4210

279.4 + .4227

279.2 + .4260

279.0 + .4305

778.8 + .4358

278.6't .4416

278. 5't .4488

CELL IY

281.1 +

280.9 +

280'.7 t

280.5'+

280. 5*

280-. E-7

280.0 +

279.8 +

279.6 1

279.4 +

279.2 2

279.0 +

278.8 ±

278.6 +

278.4 +

.4855

.4808

.4772

.4749

.4734

.4726

.4730

.4745

.4772

.4807

.4848

.4899

.4962

.5051

.5106

' GEL V

281.1;+ .4625

280.9;{ .4573

280.7-1 .4529

2S0.5'j| .4496

28Cc7-i .4474

280.1,1 .4460

279.9 ,4456

279.8;4 .4466

.279.6-

279; 4

279.2 ;+

279.0.',+

278. S ,;+

278.6 ±

278.4 .+

.4487

.4515

.4555

.4601

.4662

.4750

.4800

PHL54A11AQGLYCOLLI C-2 ,2-do ACID

I • C TAAGT. K'f + .6) x 10L •

; 5Si.o .,81.1 '

581.2

581,5

581-4

,'381.5

581.6

' 3,81.7

581.8

' 381.9

382.0

582.2

'•,582.2

582. 5

CELL I

275.0 + ,6158 7 4 . 8 + -6114

<x,

; 4 . 6 . + 2 60 77

274.4 t .6049

274. y-t .6025 '

274.1 + .6011 •

275.9 +'• .6001

275.7 + .6nq^

275.5 f. .6008

275.5 + .6017•

275.1 t .6040

273.0 + .6065

272.5 + .6100

272.6 + .6137

272.4 + .6186

ŒLL1 II l

27 5.0 ' + 16174-

2 7 4 . 8 i 16157

t 274.6 ± .-6125

= ' 2 7 4 . 4 t Lin5

2 7 4 . 5 t 26084

2 7 4 . 1 + . l o 7 6

273.7 + .6077

275.5 + .60907

273.5 + .6105 I.

275.1 ± .6132 i

273.0 + .6163 I

27 2,8 2 .6202

272.6 + .6243

272.4 t .6296.

CALL III

275.0 + .6154

274.8 ± .6101

274.6 ± .-6076-

274.5 t .6059

274.3'+ .6045

274.1 + .6942

275.-9 + .6042

275.7 + .6052

275:5'+ .6069

, 275.4 + .6091

273.-2 + .6122,

273.0 + .6157

272.8 + .6203

2 272.6 + ,6248

• 272.4 ± .6306

CELL IV

275.0 t .6 594

274.8 + .6544

,274.6 + .6505

274.4 t .'6470 274.2 t .6444

274.0 +. .6419

273.9. + .6403 273.7 + .6595

273.5 2 .6394

273.5 t 4 6597

273.1 + ' ,6409

272.9 + .6426

272.8 +'.6452

272.6 2 .6484

2722 4 t .6520

CELL

275.0; i

27.4.8: 1

274 .'.611

274.4 i. j

274. 2 [i

274.0 ;+

273.8 7+

275.4 +

273. 5- +

275.5 +

273.1 +

272.9 +

2.72,7 +

272.6 +

272.4 +'

V '

.6383

,6353

.6291

.6254

.6224.

.6200

.6184

.6175

.6174

.6177

.6189

.6206

76 2 32

.6262

.6300

REFEREN'ŒS

P.R. Wells. Linear free energy•relationships. Academic

Press, Inc., London. 1968.

J.l:'.- Lefflcr and P. Grunwald. Rates and J equilibria of

' organ ic" reactions'." '• .John "Wiley and^ons," Ihc.TT'Nev." Vorlf. \ \

1965; Symposium on linear free energy correlations.

9 Edited.by U.S. Armv Research Office, Durham,' North'

Carolina. 1964. c ' •• • '

' r- " -A.J. Streitweiser/ Jr. Ann. MA'. Acad. Sci.;84, 57.6• (1960)

A.J. Streitweiser, Jr. , •IV.C. Larigworthy, and D.E. Van

Sickle, J. Am. Chen. Soc. 84,. 251 • (1962) c '.. ^

(a) _ J. Bigeleisen and M.G. Mayer. "''J. Chem.Phys. 15,

261 (1947). ' . • . .

(b) AI. Bigeleisen. J. Chcm. Phys. 1"A, 425 (1949).

(c) J. Bigeleisen -and M. Wolfsherg. Theoretical- and '

e\j>erimentai"aspcçts of-isotope effects ID''chemical

kinetics. Ira Advances in chemical physics. Vol-. 1..

Edited by 1. Prigogine. Interscience Publishers,.Inc. - -v. ' - •,

New York. 1958. v"" " • •" ' .'

L. Melander. -Arkiv. Kemi^ 2, 1211 (1930); L. Melander.

Isotope-effects on reaction rates. Ronald Press Co,,

New York. . 1960. . , • '

S.Z. Roginskv. Theoretical principles of iso/topc methods.'

for' investigating chemical reactions. Academy of Sciences,

U.S.S.R. Press, scow. 1956.

F.B. Wilson, Jr., J.C. Deems, and P.C.. Cross. Molecular vibrations. Mc.Graw-Ilill Book Co., Inc., New York. 1955. pp. 182 - 186. ' - , " '•

—P IIr-K'c tl uiicr...... Cliem. - Rev. 61, 265 (1961J / - '-•-;•--

P.P. Bell. 'Trans. Faraday Soo. 57, 961 11961). ". R.A. More O'Ferrall and J. Kouba. J. Chcin. SOQ.7.B,;9S5 ( 1 9 6 7 ) .

P.P. Bell and J.F. Crooks. Trans. Faraday Soc.. 58, •14 09 (1962). , - . .

S.- Classtone, K.J. Faidlcr, and HJ-pyring. Tlie theorv o( rate processes. McGraw-Hill Book Go\, Inc., New York—-2 1941.

\

A.J. Streitweiser, Jr. , RJF Jagow, R.C. Fancy-, and S. Suzuki. J". Am. Chem. Soc. 8£, 2526 (1958). M. Wolfsberg and M.J. Stern. Pure'Anp.l. Chem. 8, 525

.„ (l'y 64-) r • ~— 7~ ~ ~ A.Y. Willi, dm. J. Chenil'44 , 1889 (1966). '' Y.J. Shiner, Jr. Tetrahedron, A , 245 (1959). F.S. Bartell. Tetrahedron Letters-, 6, 15 (i960)... ' L.5. Bartell. J. Chem. Phvs. 5_2l, 827 (1960). F.S, Bartell. J. An. Chem. Soc. 83, 3567 (1961). CD. Hughes, C.K. Intfold, and N.A. Taher. J. Chcm.- Soc. .949 (1940) . S. Wins te in and J. Takahashi . 'Tetrahedron, "2_, 516 (1958).

23. , V.J. Sinner, Jr. J.' Am. Chcm. Soc. 82, 265^' (i960). 24. P..S. Lewis and C.L. Boozer. J. Aiii. Chom. Soc. 74, 6306

( 195 2T. ' i • • ' •~25." "17.5V '"Lewis :and"C".b F BopzerA JO^AnO'ChemO '"Soc •.""762" '791 " " • ' • "•

(1054). - S \ , 20. V.J. Shiner, Jr. J. Am. Chem. Soc. 7_5, 2925 (1953). • '

27. M.M. Krecvoy -'and H. byring. J. .An. Chem. Soc. 79, 5121 • t ' . (1957). | '* • ; ^

28. M. Simonetta and-S.- IVinsteih. .1. An. Chem. Soc. 76, 18 • (1954) . . . • .,

' 29.. P.A. Halcvi. Secondary' isotope effects, in Progress in physical organic chemistry. Vol. 1. Pdited by',SAC Cohen, A. Streitweiser, Jr., and R.W. Taft.. Interscience • Publishers, Inc., New York. 1963.

30. V.J. Shiner, Jr. J. An. Chem. Soc. 74, 5285 (1952). ""317 P7A~Hâl75\7u TêJtraheï ' " : ~ "

52. 1 A.J. Streitweiser, Jr. and U.S. Klein. J. An. Chem. Soc. '' Sy5, 2 759 ('196.3) . ^

55. ,V..A:- Halevi and M. Nussi-m. Bull.^Rcs. Council Israel, 5", 265^(1956). ^ 1

54. ISA. Halevi, M. Mussim, and A. Ron. J. Chem. Soc. 866 / - (1965).. ' 55. P . Feldman." M.Sc. Thesis, Israel Institute of Technology. ^ ^

1960. " " . •

>

W. Van dcr Lindc and. R.E. Robertson. J. An. Chem. Soc. 86, 4505 (1964) .' -

R.W. Taft, Jr. Separation .of polar, steric, and resonance •effects -'in "rèactivi tv."" ' In 'Steric' effects in oricanic ' chemistry. Cdited bv M.S.- Newman. John Wiley and Sons, Inc. , New York. 1956. Chap. 15.

. .n P.J. Barnes and J.M.W. Scott. Can'. J. Chem. 51,. 41 i (1975) U.K. Hall, Jr. J. An. Chem. Soc. 79, 544.1 (1957).'' M. Raabo, R. G. Rates', and R.A. Robinson'.1, J. Rhys. Chcm'. 79), 54D 11900) . . 2

M-C. Brown, R.1I. Mcklaniel, and 0. ' Ilafliger. Dissociation constants. En Déterminât ion of organic'structures by physical methods. Edited by R.A. Braude and P.C. Nachod. Academic Press, Inc., New York. 1955. pp. 575 - 579. D.J.G. Ives and J.H: ,Pryor. J. Chem. Soc'2 104 (1955). TDAN'ollTcTTStE ' ancl R.E. Robertson. J. Ph}'s. Chem. 75, 1 559 ( 1969) . ' D.J. Barnes. M.Sc. Thesis, Memorial'University of New­foundland. 1966. D.J. Pasto and R. Rent. J. Org..Chem. 30, 2684 (1965). II. DC Crock ford ancl T.B. Douglas. J. An. Chem. Soc. 56, 14 2 (1954). ' HAS>Ila_rned and R.B. CVen. Tile physical chemistry of electrolytic solutions. 5rJ ed. Reinhold Uiblishing Co., Mew-York. 19587' & '"

R.A. Robinson and R.I1. Stokes. Electrolyte solutions. 2nc1 ed. Butterworths, London. • 1970". >

\ A. Albert and R.P. Serjeant. Ionization constants -of acids and bases MethucAA London A 1962."

L.J. King. Acid-base /equilibria. • Ln The international

•encyclopedia of .physical chemistry and chemical phvsics. / • ' -

Vol. -1. Ed i ted' by'R.A. Robinson, Pergamon Press, London 1965. /

<

IS Puoss and/E. Accascina. Electrolytic conductance. Interscience Publishers, Inc. , New York. 1959. J.T.. Pruc. : Tonic equilibria. In The international • encyclopedia of physical chemistry and chemical phvsics. Vol. 5. Pdi ted by R.A. Robinson-. Rergamon Press, London 1966. UA Dstwald. 2. Physik. Cliem. 2 , 56 (.1888).

E.'"KohlrauscE and L. Holborn. Das 'leitvermogen der '. elektrolyte. Teubner, Leipzig/ I-1!'1 • .*\ • • « tb.J. King. Acid-base equilibria. Tn The international encyclopedia of physical chemistry and chemical physics. Vol. 4. Ld it eel by R.A. Robinson. Pergamon Press, London, 190 5. p.V24.

P*. Kohlrausch. .Am. Physik. 50, 585 (1895); Unci. ~66, AS 5 118981 . ,

P. Debye and PA lliickel. Physik. Z. 24, 185 (4925). , •

P. Debyo and F. IlUckel. Physik. Z. 24 , 305 (1923). '

P.J. King.' Acid-base equilibria. Ln The international cnL'yclopcdiya of physical chemistry and chemicwd ..phv.slcs... .

3' "\ • ----- '- - ' V.. ..... - 1 - - • Ofc- -

Volt 4. Fdited by R.A. Robinson.'' Pergamon Press, London. .1965. p. 19. 6 . . • . •'' P,A. Guggenheim. \Phil. Mag. 174, 588 (1935) . M. Born. Z . Physik. '1 , 45 (1920); cf. R.A. Moel wyn-Hughes. Physical clicmistry. ,2nd e d . Pergamon Press, London. 1961. p. 895. '' >>-. ' ' L. Onsager. Physik. Z.-. '2J7,X38.8 (1920).

1

L. Onsager. Thysik. 2. 28, 227, (1927). F.D. Rossini, F.T. Gucker, Jr., iP.L. Johnston, F. Pauling,' and G.W. Vmal. J. Am. Qiem. Soc. 74y 2699 (1*952) . R. Fuoss and F. Accascina. Electrolytic conductance. Interscience IJiblishers, Inc., New'York. 1959. pp. 195 -196.-

v F. Pitts. Proc. Roy. Soc. A217, 43 (1955). R. TFuoss and L. Onsager. Proc. Natl. Acad. Sci. U.S. 41, -274 (1955).

S. Arrhenius. Z. Physik. Chem. _1, 651 (1887),

R. Fuoss and C.A. Kraus. J. .Am. Chem. Soc, 55, 476 (19.55).

'T. Shedlovsky. J. Franklin Inst. 225, 739 (1958)*.

1 RM. Daggett1, Jr. J. Am. Chem. Soc. 775, 4977 (1951)..2-/

D.J.G. Ives. J. Chem. Soc. 751 (1955). /.*

M.S. Sherrill and A. A. Noyes. J. Am. Chem. Soc. 4 8 , 1861 [1926). . 6 D. A • Mac I nnes. J. Am. Chem. Soc. 48.20^X122.61 IRA. Maclnnes and T. Shcdlovsky. J; An. Chem. Soc. 5 4 ,

((429 ( 1 9 5 2 ) . .

R.AyRobinson and R.H. • Stokes.. Electrolyte solutions. • 2nd ed. Butterworths, London. , 1970. pp. 336 - 369. R .A. Robinson and R.H. Stokes. Electrolyte solutions. 2nd cd. Buttonvorths, London. 1070. pp. 235,,- 238. '• D.J. Barnes, P..P. Golding arid J.M.W. ' Scott. Can. J. Chem. In press. \ " ' , ;

D.J. Barnes, 11.(5. Benson, R.D. Golding, and J.M.IV. -Scott. To Lie published. \ • J.R.J. -Dippy and E.R. Iv'i 11 iants. J. CTiem. Soc. 161 (1934). J.F.J. Dippy and F.R. iv'illiams. J. Chem. Soc. 1888 fl9A4) P. Belcher. J. Am. Chem. Soc.' 6y£, 2744':( 1938). A. Fischer, B.R. Mann, and J. Vaughan.. J. Chem. Soc. 1093'(1961) . " ' ' (A Jones,, and B.C. Bradshaw. J. Am. Chan. Spc. 55, 1780 (1935). - 1 • ' T. Sbedlovsky. Conductometry. hi'Physical methods oE • organic chemistry. 2nd eel. Part Tl. ' Edited -by A. 'Aeissberger. I-ntcrsciejice Publishers, Inc., Mew York. .1949'.

2 8 :

S o . I I . M . D a g g e t t , J r . , ' P . J . B l a i r , ' a n d C . A - . K r a n s . J . . A m .

C h c m - ; S o c . 75, 700 , 12>S1 ) . f ' \ . '• .

8 . . , \ \ \ a n d c r l . i n d o , . 1 ) N ( ) r . t l K - o - W - ^ H 4 ^ R e d ] i ] o n d - ^ - f ( n d - R - l ^ — -

' R o b e r t s o i r . L ' a n . S . C h ô m e 4 7 , -279 1,1 999) .

8 8 . 77. 1 . Y o g e l . A ' t e x t b o o k o f p r a c t i c a l , o r g a n i c c h e m i s t r y .

^ 5 r d e d . L o n g m a n s , - L o n d o n . 1 9 o 4 . p . ] ~ 2 .

8 7 . H a n d b o o k o k c h e m i s t r y a n d p h y s i c s . 4 1 s t e d . , C h e m i c a l

R u b b e r I ' u b l L s h i n g C 'A- . - , , C l e v e l a n d . • - R 9 5 9 . p . 1 2 5 5 . ,

99. r C Y . d l a v e s a n d C . k . K . . B r a n c h . . 1 . A m . C l i e n t . S o c . o 5 ,

1 5 5 5 ( 1 7 4 5 ) . ' ;

7 1 . A . I . V o g e l . A t e x t b o o k o k ] ) r a c t t e a 1 o r g a n i c c l i e . n n s t r v .

5 r d e d . L o n g m a n s ? L o n d o n . 1 9 0 4 . p . 1 7 5 .

92. A . I . V o g e l . A- t e x t b o o k o f p r a c t i c a l o r g a n Lc c l i c u i i s t i y , '

5 i \ ! e J . L o n v m a n s , L o n d o ' n . 1 9 6 4 . p . - 1 2 8 .

7 a . I I t i n t i ' e s s . O r g a n i c c h l o r i n e _ c o m p o u n d s . J o h n \\ i . l c \ : . . a n d .

. ( S o n s , Inc'. , Rc-v. Y o r k . - 1 7 4 8 . p . 1 5 2

7 4 . 77.1. L e o n a r d a n d C . K . J o h n s o n . J . O r g . C h e m . 2 " , 2 8 2 ( 1 9 ( 7 2 ' )

9 5 . A . l ; V o g e l . A t e x t b o o k o f p r a c t i c a l o r g a n i c c h e m i s t r y .

5 r d e d . L o n g m a n s , L o n d o n . 1 9 ^ 4 . p . 1 C l .

9 o . H a n d b o o k o i c h e i n i s t i y a n d p h y s i c s . 5 1 s t e d . C h e m i c a l

R u b b e r P u b l i s h i n g " C o . , C l e v e l a n d . 1 9 7 0 . p . H - . 1 0 0 .

7 9 7 . , IV . J . I l a m e r . T h e s t r u c t u r e o f - e l e c t r o l y t i c s o l u t i o n s . J o h n

L i l e v a n d S o n s , I n c . , Nov.- Y o r k . 1 9 5 9 . . p ' ; 1 6 " . ^

9 8 . , 1 . 1 7 . k i n d ' , J r . , J . J . C w o l e n i k , a n d P . M . I l f e s s . J . A m .

C l i e m . S o c . 8 J _ , 1 8 5 7 | 1 9 5 0 ) .

' ' i • . ' s , •

a-

Handbook'of chemistry and physics, 41st ed. Chemical

Rubber Publishing Co., Cleveland. 1959. -p. 2122.

Handbook of chemistiT_aiKLph\:slcs—_4J.-5.t-ed-.—Gheirii ea-l-r-

Rubber lliblishing Co., Cleveland. 1959. p. 627.

Handbook-of chemistry and physics. 41st ed. Chemical

Rubber Publishing Co., Cleveland. 1959. p. 771..

G.H. Jeff erg' < and A. 1 . Yogel., J. Chem. Soc. 166.(1954)'./

'...C. IAier and R.A. Robinson. J. Chem. Soc. B, 2575

(1971). " , - -

P. Laughton .and A. Demayo. Private communication.

b.J. King and J.b. Prue. J. Chem. Soc. 275 (1961).

A. Ostwakl. Z. Physik. Chem. 5, 184 (1889).

T. Shedlovsky, A.S. Brown, and p.A. Midlines. Trans.

Plectrochein. Soc. 66, 165 (1955). *

b. Saxton and T.K. banger.''' .J.' Am. CHem. Soc._55, 3<ij5.S

( 1 9 5 5 ) . • . .

T. Shedlqvsky and R.L. Kay. J. Phys. Chem. (y£, 151' (1956)

D.A. HacInncV, TA Skcdlovsky, and L.C. Longsworth. Chem. '

Rev. 15, 29 I 1 955) . ' "*'' \ .

P . P . Go!ding% M.Sc. Thesis, Memorial University of Newfoundland. 1968. • "/

J.IR Pryor. Pli. •hes!is., Birkbeck College, University

of London. 1954. ' " - "

H.J. Pasto, I). McMillan, and Minphy. J. Org. Chem. 30,

v i • . • • • .

284"

1]4.. R. l.awiierer. her. 4_2, 2282 (1909V, 2212 (1910). MS. _ P. Walker and J. Lci'b.- Can. J. Chein. £0, 1242 (1962). iLLu—IwA^lAVHr^ TV. \ i-iva sulutions A •

2nd ed .''Ruttcruorths, London. 1070. Chap. V IJ 7 . - 11. C. .Reason . Private commun i cal i on.

ILS. O.K. Mesels, P.C. Scholten, and K.J. Myscls. J. Phvs. - • Chem. 74, 1 147' (1970) . ' '

119. ICS. I'catos and D.J.C. Ives.. J. Chem. Soc. 2798 (1956). 120. I •'. S . Pea te.--., D.J .C. Ives, and J.11. Pryor. J. bVctroehcm.

Soc. j_05, 580 (19561 .

121. .tat R.A. Robinson .and R.Î1. Stokes. Clectrolvte solutions 2nd ed. battel "Worths, London. 1970. pp. 92 - 95.

(h) Hyjd. p. 5.

122. D.J.Ç. Ives and 1AC.AA rVselev. J. (Them. Soc, 1',, 1655

125. M,L: KilpatrLck. J. Chem. Rhys. 8, 506 (1 940).

154. (a) D.J.C. Ives and KT Sames. J. Chem. Soc. 511,(1945). (b) kVV. 515 I .1945 1 .

125. D.J.(A Ives and R.D. Marsden. J. Chem'. Soc. 649 (1965). 120. D.J.G. Ives and T.G.N. Moseley. J. Chem. SocVP, 757

. ( 1 966 ) . . :

12'. A. Katchalskv, II. husenbery, and $ hifson. J. Am. Chem.

Soc. 75y, 5889 (1951 ) -, 128. T. Shedlovsky and D.A. Maclnnes. J. An.- Chem. Soc'. 57,

VOS V955) :

2SS

129. E . Saxtori-and 1ER. Meier. ' J. Am. Cher?,. Soc. 56_, 1918 (ÎS54J. . _ .

• A — . —

~v .'.3T" ;u)u M.v.Ki-lpatrickv-;); -Am:':ChemS Hoc.' 56","""

i 483 (1954). =•

151: R.14 Roll and . W . B . T . Miller. 1Vans. Faraday Soc. 59, •

114 7 ( 19(i3) . ' • ' • '

)85. Ci.A. Ropp. J. Am. Chein. Soc. 84, 4352 (1990).

155. J 444V.'Scott. Private communient ion. ^

134: R.A. Robinson and R.l'l. Stokes, electrolyte solutions.

2nd ed. Butterworths, London., 19TO. pp. 118 •- 152.

135. R.A. Moelunn-Hughes, Physical chemistiy. 2nd ed.

Pergamon Press, London. 19(4. pp. 856 - 862.

136. C, Atkinson ;md 44 Mori . 4. Phys. Chesffi. 71 , 5525 (4267);

R. Fernmidez-Prini and G; Atkinson. 9. Rhys. Chem. 75,

T4, Cotlrcll. The .strengths of chemical hoir A. 2nd cd >

Rutterworths, London. 1958. pp. 2"9 : 276'. '

*->H- U.S. flamed and (4P. Oven. .The physical chemistry of

electrolytic solutions. 5rd ed . Re inho Id lYiblishing Co., New York. 1958. p. 251. ' • • •

• 139. P. Las~lo and 2 . Welvart. Bull. Soc. Chim. France, 7, 2412 ( 1 9 e o ) .

140] F.K. Tliointon-and L.R. Thornton. Origin and interpretation J

of isotope effects. In Isotope effects in chemical reactions'. Fdited by C . . J . Collins and N.S. Bowman. Van Nostrand RoinhoId Co., New Jersey. 1970. p. 2Î3.

286

41.' S. Micushima. -Structure of molecules ..nil internal rotation

Academic Press, Inc., Mew York. "loSD; S. Miiuslnnia. Pure'

---—Appl. C) tern.-- '7 ,- - J - (-1 Ado j - " .-•

142. U.S. Outowsky. J. Shorn. Phvs. 377_, 219(2 (19(>2).

BBS. M. RYban. 'Vet rahedron ketters, 2_7_, 31 OS ( 1990)..

144. d.A. I'ople, VA (A Schneider, and 11.(A Bernstein. High

resolution nuclear magnetic resonance. McOrau--11111 P.ook

Co., Inc. ,• New York. 1959. pp. 377. - 383.

143. S. Oae, M. Yokoyama, and M. Rise. Bull . ' Chem. • Soc .*

Japan, .4]_, .1 221 (1908) .

140. M. Oki and II. \lwamura. Tetrahedron ketters, 25., 2917

(.1900) .

147. 11.S. Prank and MAV. I Vans. J. Chem. 1'hys. 1 3 , 507 ( 1945)

148. lAC. Bingham. ,1 7 Phys .• Cheiii, 4j52, 885 (1941 j.

-14o-r— l— Jrshi'0'~an'd" '7A"ltoT'" Cl TT"'VlwnnT'Bvil'ï. V3, U 9 2 (l9t.5). 150. M. NLshio. Chem. Phann. Bull. jAg, 16(A) '(1997).

151. M. Nislno. Chem. Commun. 562 (.1968). A :>>• 152., M. ..ishio. Private communication.

155. (AM. 'Win tes nies, J.J. Crocki, 0. Holt:., 11. Steinberg,

and J.I . Roberts.' J. An. Chem. Soc. 8A, 1058 ( 1965).

134. R. Davies and.), lludec. Chein. Commun. 1 24 (1972).

155. R.F. Watson and J.PA hastham. J. Am. Chem. Soc. 87,

-604 (19(05). • '

156. h. Bullock, J.M.W-. Scott, and P.D. Golding- Chem. Commun. 168 (1967).

L. Bunco 1 . Private communication. . .

,A. Rauk,'R. Bunco], R.Y.-Nfoir, ami S. Wol fe.,-,1. Am. Chcm , Soc. - S7_, • 54 98. (19o5)-~~ " " ] "v -- -----

S. Wolfe and A. Rauk.. -Chem. Commun. ~78 (i960).

S.-Wolfe, A. Rauk, and I.C. Csiumadia. ,J. Am. Chem. Soc.

8 9 , 7w 1 0 (l '9(>?) t • '

S. Wolfe. Accounts Chem. Res. 5, 102 (1072). -

B..J. Hutchinson,, K.K. Andersen, and A.R. KatritAky. .1.

An. Chem. Soc. 7tl_, 3830. (19*09). ' '

S. Wolfe, A. Rauk, and I.C. Cs'izmadia. -J. Am. Chem.

Soc. 9J_, 1 507 (1909) . • . • ,

A. Rank, S. Wolfe, and I.C. Csi zinadia. Can. J. Chem.

•r, 1 13 (1969).

O.k. lkaddwin, R.L. llackler, and P.M. Scott. Chcm.

ConimunT-2k-kV5AC1969)7 ; '"*~ ~ :

S. Volt'e, A. Rr.uk, L.M. Tel, and k.G. Csizmadia. . , 1 . Chem.. Soc. R, 136 ( 1971).. • • ' •

Y.A. kuttringhaAs and A. k'olb. 2 . Naturiorsch. lob » >

7 7 ( 19n) A ' • ' •

b.A. Lchto and R.A. Shirley. .1. Org. Chem. 22, "989 (1957 )

A. Jumar and W. Sehultzc. J.- Rrakt. Chem. [4], 5, 85 (195 A).

A.l. Vogel. A textbook of practical 'organic chemistry.

5rd cJ. Longmans, iLondon. 1964. pp. 591 - 595.

B. Chauncy and 12. Gellert. Aust. J. a\em.'22, 995 (1969).

N.G. Clark,.-J. 12. Cranham, D. Greenwood, J.R. Marshall, ' •••

and li.A. Stevenson. J. Sci. Food Agr. ' 8 , 566 (1957).

' 'n : i ; y. 1970. ' .

L.A. lins. Ph.D. Thesis,NCase Western Reserve University.

1969. - ,

P.S. Dewar, A.R. Forrester, and R.ll. Thomson. J.C.S.

Perkin I , 285" (li!72).

R.W. Rabidcau, Te. C Harvey, and J.B. Stothers . Chcm.,

Commun. 1905 (1969) . X

M. Okd , I R * Iwamura, and N. Jlayakawa. kAill. Chem. Soc.

.Jar m, TA,' 1865 (1964) .

K. Mislow and IRR. Ilopps. d. An. Chcm. Soc. S£,/.5018

01462). A-

A. L ,-Tcrnay-,-.Jr.->~D. W .—Chasai'— and-Mr- Saxr-^J—OrgTrChem.

52_, 2465 (1 967). \. " 7 5

AVR. TFrnay, Jr. and D.W. Chasar. J. Org. Chem. 52, 5814

( 19(A) .

A.R. Tcrnay, Jr. and n . W . Qiasar. J. Org. Chem. 55, 2257

(1968). , , . i

A. R. Temay, Jr. and D.W. Chasar. J. Org. Chem. 33, 5641

(1968).

A.R. Temay, Jr., L. ]:.ns, J. Hermann/ and S. F.vaiis.- J. .

Org.' Chem. 54, 940 (4969). . '

P.T. banslaary, J.P. hcirojr, and A.J. Lâcher-. ' J.' Am. Ahem.7 Soc .' 88, 1482 (1966), and references cited therein. • • . ' ' • <

•te^T*) O'-Swingle, .'. • P. Viau, and YJV. • Wigf iolcl. Can. J. Cliem. 48, •

• 2148 (. 1970J . -<* .. . 3 -

(h) J'. burst, R. Viau, and M.R. Mc.Clory.' J.'Ain. Chcm. ; Soc. 93, 3077 (1971). ,

(el R. Viau and I. Diirst . S. Am. Chein. Soc.. AS-, 134 0 (1975).

M.1A P'Amorc 'and J.I. Rrauman. Chem. Commun : 598 (1973). (a) K. Nishihata and M. Nishio. Chem. Commun. 958 (1 971) (Jo) K. Nishihata and MNishio. J.C.S1'Perkin II, 1750

(1 972).

R..R. Robertson. Can. J. Ahem. 35, J 550 (1955). IA.R.-Murr. 141. P.--Phes-i s-,—1 ndi ana-Un i vers ity-;—-19(.i IT

HRIvVI'A

290

p. 3S, li ne .5. ' • . ' •

l.quat ion [24] is obtained froi.'i a cons t de rat ion of Equations i J _ 3 2 i . , ~ | . 2 J - ) - a i i d — ^ — 1 — * — - — ~

( 1 -et') 1'

dus Equation may, however, be obtained from simpler assumptions

I'ae el ass ici I -equi 1 ibiduii: constant, K., given hv Equation • [29J a

•X ' C

i l - . f )

7

i s d e p e n d e n t o n l y u p o n t h e c o n c e n t r a t i o n s o f t h e v a r i o u s

p r e s e n t , e x p r e s s e d i n t h e f o r m o f a g e n e r a ] e q u i l i b r i u m I

cm**h^xyl i c a c i d s m a q u e o u s m e d i a , i . e . ,

s p e c i e :

o r w x x i l

u i c h t h a t

liA + 100 OP t+E

00'' '][,

M o w c v e i , s i n c e a c t i v i t i e s » a i r a t h e r t h a n c o n c e n t r â t i o n s

a p p r o p r i a t e t o " t h e n i i o d y n a m i c e q u i l i b r i a , t h ' e e x p r e s s i o n n

r e w r i t t e n a s

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Siiico the respective activities arc equal uv the products of the concentrât ions of tlie species and- their appropriate activity coell uMcnts, -the expt'^g-uaaJJ^ ,—•—_-

AdAedi \< Puliation [ c l ] as stated.

i t s h v u l d h e n o t e d t h a t P e s i v i e s t h e e k - i t r o n l j o r e t i c a n d

\- - ' - i r e l a x a t i o n e j f e c t s , t h e o r i g i n a l O n s a p e r 1 o n n u l a t i o n a l s o i n -

i \ I

e t u d e s a " v i s c o u s d r a p ' e f f e c t " w h i c h a r i s e s f r o m a c o n s n l e r a t h a i

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e x p r e s s i o n f o i j t h e c a s e o f w e a k e l - c e t r o l v t e s n n l v . A d i s c u s s i o n

e l ' t h i s p o i n t a s p r e s e n t e d m o r e ' f i i l î v i n r e f e i c n c e l i é •/

/

r-. 1 i n e ' s o J o . , _ ".

l A A o r e n c b ' s t o s u p p o r t t h e s t a t e m e n t i d u c l " r e a d s y j f > n d e e d ,

D i e v a l i d i t y o f ; ' t h e i r a p p l i c a t i o n t e a r i d s o l v i t i o n - A h i i s / b e e n

q u e s t i o n e d , u i a;^ m u c h a s t h e s e t r e a t m e n t s c o n s i d e r j ' o n i / c m i i > r a ­

i l " , \ . '

t i e n a s ' s u h i i i n y t û p e - l i b e " m o t i o n , w h e r e a s . " p r o f o n l u m p s ' ' i i A p . b t

he v ' H i t i c i p a t e d fry t l i o m e n t a t i o n o f n v d r o n i u m P a n , \are

p r o v i d e d ' h y - j f h e f o l l o w i n g : • ', - < ? ' . . -

( a ) R . J . K i n g . _ A c i l l - b a s e e q u i l i b r i a . In The i n t e r n a t l o n ' a .

c n c v c l o p e d i a . . o J J _ p h . y ^ i ^

V o l . - 1 . bel i t e d - b y R . A . R o b i n s o n . P e r g a m o n P r e s s , -

' L o n d o n . 1% 5 . p . . ' 248 .' '' , •

( b ) ' R . A . R o b i n s o n a n d R . l l . S t o i c s . L l e c t r o l V t e s o l u t i o n s .

2nd e d . B u t t c n w o r t h s , L o n d o n . , l . C O . - p . 121.

. p . - V d , l i n e P . ' • '

I q u a t i o n [ 8 1 | , c h i e f ) i s g i v e n a s

il 31 ) RU) = -1 - c{ 1 -c i 1 -cCctc. ) "'21

i s s u p p o r t e d b y t h e l o i l o w i n g r e f e r e n c e ^ : ! _ , „

K . J . K i n g . A c i d - b a s e e q u i l i b r i a . iRn T h e i n t e r n a t i o n a l ,

e n c y c l o p e d i a o f p h y s i c a l c h e m i s t r y a n d c h e m i c a l p h y s i c s ,

v o l . 4 . P.d i t e d h y 1 L - A . R o b i n s o n . P e r g a m o n P r e s s , L o n d o n .

l o f S . p . 4 L .

S - t . P .

T h e 1 d i a l s t e p - in t h e p r e p a r a t i o n o f t h e c e l l s f o r c o n d u c ­

t a n c e m e a s u r e m e n t s , p r i o r t o t h e d e t e r m i n a t i o n o f t h e v a r i o u s

c e l l c o n s t a n t s , w a s t h e s e a s o n i n g o f t h e c e l l s w i t h a s o l u t i o n

o f p u r i f i e d p h o n e L a c e t i c a c i d . I t s h o u l d b e n o t e d t h a t t h e

c e l l s c e r e s u b s e q u e n t l y R e a s o n e d ^ w i t h We 1 u t i o n s / o f , t h e ' o t h e r

. a c i d s e x a m i n e d m t h e s t u d y p r i o r t o t l\e - r e d e t ç m n i n a t i o n o f t h e

c e l l c o n s t a n t s a n d - t h e i n v e s t i c a t i o n o f \ t h c ' c c / n d u e t 1 v i t y o l V

solutions of these acidsl

\

I t i s a l s o ' n o t e w o r t h y . t h a t f o l l o w i m ' t b / e c . e 4 4 c l e a n i n g

p r o c e s s ' , t h e o b s e r v e d r e b i s t a n c e s d J t h e , . s o l u t : i o n . . , o t . . . p . u . i 4 1 , i e d

p h e n v l a c e t i c a c i d u s e d A ; o s c a ' s o n ' t h e c e l l s w e r e s i g n i f i c a n t l y

' . / •" ' ' 4 \ \ . • . 1 a r g e r t h a n t h e a n t i c i p a t e d r e s i s t a n c e s . 1 b e s t .d i f I e r e n c e s

. / • / } ''''

i n r e s i s t a n c e c o i n c , i d l e d w i t h a l o s s i n \on'js c o n c e n t i ' a t i o n

w h i c h a p p r o x i m a t e l y c o r r e s p o n d e d t o a m o n o l x i y é r d e p o s i t o f

t l x - a c i d o n t h e c l e a n s u r f a c e s o f t h e ' s o l u t i o n f l a s k a n d c e l l s .

p . 1 2 0 , 1 m e s 1 - 0 /

T h e f r e q u e n c y d e p e n d e n c e o f ' t h e r e s i s t a n c e s o l s o l u t i o n s

o l p h e n o x v a c e t i c a n d p h e n o x y a c e t i c - 2 , 2 - d - : a c i d s v a i s e x a m i n e d .

U s i n g f h e G . R . I A'., r e s i s t a n c e s o f c a - 5 0 ( H ) s w e r e r e c o r d e d f d r

4 l i e m o s t d i l u t e s o l u t i o n s ô f t h e s e a c i d s ( h e n c e , t h e m o s t

J

. s u s c e p t i b l e t o f r e q u e n c y d e p e n d e n c e ) , a n d ' t h e . r e s i s t a n c e s r e . -

. c o r d e d a t 1 0 0 c p s d i f f e r e d b y n o t m o r e t h a n 0 . 0 s: f r o m t h o s e

r e c o r d e d a t 1 0 0 0 c p s . . .

/ "

- . " / i

p p . 1 8 2 - 1 8 . 3 . / \

T h e i n i t i a l s t e p s i n t h e s y n t h e s i s o f 9-tin a - 0 , 1 0 - c l i h v d r o -

/ ' ' 1 p h c n a n t h r c n e - f J r o x i d e a r e d e s c r i b e d a n d ; t h e i s o l a t i o n o f p u r e

ooiitr'obeniyl phenyl sulfide and. o--aminohency 1 ipheny 1 ' suffk'.e is claimed, p?ven though in eaclg.react i on step mixtures of the res-

- ' — i , , .... i Sfa , .j.:..},™™ ••• - ' • " , —

' _ . - _ . - - t - - - / ' ' f

'• pectivc io-'and p- isomers were used. 'This apparent anomaly is explained by the'fact that the réaction steps were carried out

' using the mix tyre s a? .-stated, but 'small samples were set aside tùr analyses., These samples; gave reasonably sharp melting

•points and yielded spectra fi.r., n.m.r. and m.s.i from which it/was extî-cmely difficult to'discern the'fact that they were • .impure. • Investigation of'the integrity of the;starting material was not .initiated' until .after the Pschorr reaction products .were' examined. In the cyiirse ot the investigation, pure samples of tlie respective o--yind p;r isomers of nitrobcntyl phenyl sulfide and aimnohency 1 phenyl'sulfide were isolated. Consequently, although the initial reactions wore carried out on material, the bulk oi which proved to bo a mixture, the pure o- isomers were- isolated and their properties appropriately recorded.

PP. iKbbb. ;

The notation " ( 1 h-S"-Sn the Thesis is used to represent ' the -vibrational stretching modes of hydrogen atoms attached to carbon in methylene groups, adjacent to unoxiJised sulfur atoms. Tims -follows the notation used in

.'N.i'C Colthup, L.il. Paly, and S.k. Vuborlev. Introduction to inirared and ranan spectroscopy. Academic Id-ess, Inc., New York. 196-4 .' p. 596.

29 S

This notation may he misleading and -these vibrational modes are

perhaps better represented by "P-Ibof Ol.-S' . 1'he ' erroneous

notât ioip| o c c u r s on the Toi lowing pages in the t e x t s

p. 184

p . 187

p . 18,5

p . 189

p . 191

n ICS

1 i ne 9g

1 me J b ;

1 me r ; 1 m e 1 (4 ;

l i n e 19g

1 me 2 0 .