69-4833 AMBURN II, Hershel W alter, 1941 - OhioLINK ETD ...
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This dissertation has been microfilmed exactly as received 69-4833 AMBURN II, Hershel Walter, 1941- RATES OF NEUTRALIZATION AND IONIZATION CONSTANTS OF HOMOLOGOUS NITROCYCLO- ALKANES. The Ohio State University, Ph.D., 1968 Chemistry, organic University Microfilms, Inc., Ann Arbor, Michigan
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Transcript of 69-4833 AMBURN II, Hershel W alter, 1941 - OhioLINK ETD ...
This dissertation h a s b e e n microfilm ed exactly as rece iv ed 69-4833
AMBURN II, H ershel W alter, 1941- RATES OF NEUTRALIZATION AND IONIZATION CONSTANTS OF HOMOLOGOUS NITROCYCLO- ALKANES.
The Ohio State U niversity , Ph.D ., 1968 C hem istry , organic
University Microfilms, Inc., Ann Arbor, Michigan
RATES OF NEUTRALIZATION AMD IONIZATION CONSTANTS OF HOMOLOGOUS NITROCYCLOALILANES
DISSERTATION
P r e s e n t e d i n P a r t i a l F u l f i l l m e n t o f t h e R e q u i r e m e n t s f o r t h e D e g re e D o c to r o f P l i i l o s o p l iy i n t h e G r a d u a t e S ch o o l o f
The Ohio S t a t e U n i v e r s i t y
By
H e r s h e l W a l t e r AiTourn I I , B.S ,
* * * ÿ: A
The Ohio S t a t e U n i v e r s i t y 1968
Approved by
j .Ativ iser
D e p a r t m e n t o f C h e m i s t r y
D e d i c a t e d t o my m o t h e r and f a t h e r an d t o J u d i t h
11
ACKNOWLEDGMENTS
I wou ld l i k e t o e x p r e s s my g r a t i t u d e t o D o c t o r H a r o l d
S h e c h t e r f o r s u g g e s t i n g t h i s p r o b l e m and f o r t h e many c o n t r i
b u t i o n s h e made t o me i n a l l a r e a s d u r i n g o u r a s s o c i a t i o n .
I wou ld l i k e t o t h a n k my f e l l o w g r a d u a t e s t u d e n t s and
t h e s t a f f o f t h e D e p a r t m e n t o f C h e m i s t r y whose t i m e and c o u n s e l
h a v e c o n t r i b u t e d t o t h e c o m p l e t i o n o f t h i s w o rk .
I wou ld f i n a l l y l i k e t o e x p r e s s my a p p r e c i a t i o n f o r t h e
o p p o r t u n i t i e s a f f o r d e d me by t h e D e p a r t m e n t o f C h e m i s t r y , w h ich
I s e r v e d as a T e a c h i n g A s s i s t a n t ; t h e N a t i o n a l I n s t i t u t e o f
H e a l t h , w h ich I s e r v e d a s a R e s e a r c h F e l l o w ; t h e Ohio S t a t e
U n i v e r s i t y R e s e a r c h F o u n d a t i o n , w h ich I s e r v e d a s a G r a d u a t e
R e s e a r c h A s s i s t a n t , and t h e Du P o n t Company f o r whom I worked
d u r i n g t h e summer o f 1964 .
ill
VITA
S e p t e m b e r 28 , 1941 . . . . . . . . . Born - A k r o n , Ohio
1 963 ............................................................................ B . S . , D e n i s o n U n i v e r s i t y ,G r a n v i l l e , Ohio
1 9 6 3 - 1 9 6 5 . . . ..................... .......................... T e a c h i n g A s s i s t a n t , D e p a r t ment o f C h e m i s t r y , The Ohio S t a t e U n i v e r s i t y , Columbus, Ohio
1 9 6 5 - 1 9 6 8 ..................................................................N a t i o n a l I n s t i t u t e o f H e a l t hP r e d o c t o r a l F e l l o w
1 963 ............................................................................ G r a d u a t e R e s e a r c h A s s i s t a n t ,D e p a r t m e n t o f C h e m i s t r y , The Ohio S t a t e U n i v e r s i t y , Columbus , O hio
I V
CONTENTS
Page
ACKNOWLEDGMENTS ................................................................................................ i i i
VITA............................................................................................................................... i v
TABLES.......................................................................................................................... v i i i
FIGURES .................................................................................................................... X
I . INTRODUCTION...................................................................................... 1
I I . i; IS TORY AND THEORY....................................................................... 5
S t r u c t u r e and R e a c t i v i t y o f A c i d i cN i t r o C o n . p o u n d s ............................................................................ 5
I n t r o d u c t i o n ............................................................................ 5
’ 'ecHanistr; o f N e u t r a l i z a t i o n -De vel opmen t o f T heory ................................................... 7
R a te o f N e u t r a l i z a t i o n - E f f e c t o f S t r u c t u r e , S o l v e n t andD e u te r i u m I s o t o p e ................................................................... 11
A c i d i c N i t r o Compounds as R e f e r e n c e A c id s . 20
I o n i z a t i o n C o n s t a n t s and B r o n s t e dC o r r e l a t i o n s f o r N i t r o Compounds .......................... 21
F a c t o r s A f f e c t i n g R e a c t i v i t i e s i n C y c l i cS y s t e m s ................................................................................................ 36
I - S t r a i n T h e o ry .................................................................. 36
R e a c t i o n S e r i e s C o r r e l a t e d byI - S t r a i n T h e o r y .................................................................. 40
Two O t h e r R e a c t i o n S e r i e s C o r r e l a t i n gI - S t r a i n T h e o r y .................................................................. 44
CONTENTS (Continued)
Page
I I I . RESULTS AND DISCUSSION............................................................. 53
IV, EXPERIMENTAL.................................................................................. 92
G e n e r a l P r o c e d u r e s and T e c h n i q u e s .............................. 92
Gas C h r o m a t o g r a p h i c A n a l y s i s ................................... 92
P r e c i s i o n R e c t i f i c a t i o n T e c h n i q u e s .................... 92
P r e p a r a t i o n and P u r i f i c a t i o n o f N i t r oC o m p o u n d s ........................................................................................... 93
2 - - K i t r o p r o p a n e ....................................................................... 93
X i t r o c y c l o b u t a n e .................................................................. 94
N i t r o c y c l o p c n t a n e ............................................................ 95
N i t r o c y c l o h e x a n e ................................................................. 95
N i t r c ' C y c l o h e p t a n e ............................................................. 96
N i t r o c y c l o o c t a n e ................................................................. 96
Equipment f o r D e t e r m i n a t i o n o f R a t e s o fN e u t r a l i z a t i o n and I o n i z a t i o n C o n s t a n t s . . . . 97
C o n s t a n t T e m p e r a t u r e C o n t r o l ................................... 9 7
C o n d u c t i v i t y B r i d g e ........................................................ 98
C o n d u c t i v i t y C e l l s ............................................................. 98
S y r i n g e s ...................................................................................... 102
P o t e n t i o m e t e r ....................................................................... 102
pH C e l l s ...................................................................................... 102
P r e p a r a t i o n o f R e a g e n t s and S o l u t i o n s .................... 103
H y d r o x i d e I o n C a t a l y s i s .............................................. 103
vi
CONTENTS (Continued)
Page
M e t h o x i d e I o n C a t a l y s i s ............................................... 104
E t h o x i d e I o n C a t a l y s i s .................................................... 105
G l y c o l a t e I o n C a t a l y s i s ............................................... 106
T r i e t h y l a m i n e C a t a l y s i s . 108
D e t e r m i n a t i o n o f A p p a r en tI o n i z a t i o n C o n s t a n t s ......................................................... 109
P h y s i c a l M e a s u r e m e n t s ............................................................. I l l
h y d r o x i d e I o n C a t a l y s i s ................................................ I l l
M e t h o x i d e I o n C a t a l y s i s ................................................ 113
E t h o x i d e I o n C a t a l y s i s .................................................... 113
G l y c o l a t e I o n C a t a l y s i s ................................................ 114
D e u t e r i u m E x c h a n g e ............................................................ 115
T r i e t h y l a m i n e C a t a l y s i s .............................................. 118
D e t e r m i n a t i o n o f A p p a r e n tI o n i z a t i o n C o n s t a n t s ......................................................... 119
D e t e r m i n a t i o n o f t h e I o n i z a t i o nC o n s t a n t o f T r i e t h y l a m i n e ......................................... 121
M a t h e m a t i c a l A n a l y s i s o f K i n e t i c S y s te m . . . . 122
N e u t r a l i z a t i o n o f A c i d i c N i t r o Compounds . . 122
A c t i v a t i o n P a r a m e t e r s f o r Amine C a t a l y s i s . 125
Time I n f i n i t y f o r K i n e t i c E x p e r i m e n t s . . . 126
V. APPENDIX 1 ............................................................................................ 128
vii
TABLES
Table Page
1 0 .
11.
R a t e C o n s t a n t s f o r N e u t r a l i z a t i o n o fN i t r c a l k . m e s by Sodium H y d ro x i d e i n W a te r . . . . 13
R a t e C o n s t a n t s f o r N e u t r a l i z a t i o n o f N i t r o a l k a n e s by Sodium H y d r o x id e i n 50%by Volume 1 , 4-Dloxane-V.’a t e r a t 0 ° ............... 13
R a t e C o n s t a n t s f o r N e u t r a l i z a t i o n o f 2 - N i t r o p r o p a n e by Sodium H y d r o x id e a t0° as a F u n c t i o n o f S o l v e n t C o m p o s i t i o n . 15
A p p r o x i m a t e maximum V a l u e s f o r K i n e t i cI s o t o p e E f f e c t s .................................................................................. 18
D e u te r i u m I s o t o p e E f f e c t s i n N e u t r a l i z a t i o n o f N i t r o c y c l o a l k a n e s by Sodium H y d r o x i d e .................... 18
I o n i z a t i o n C o n s t a n t s o f N i t r o a l k a n e s andNi t r e n t e A c id s i n W a te r a t 2 5 ° .............................................. 23
I o n i z a t i o n C o n s t a n t s o f N i t r o a l k a n e s i n50% Aqueous E t h a n o l .................................................. 23
R a t e C o n s t a n t s f o r N e u t r a l i z a t i o n and I o n i z a t i o n C o n s t a n t s o f N e t a - and P a r a - S u b s t i t u t e d l - ? h e n y l n i t r o e t h a n e s i n50% by Volume 1 , 4 - D i o x a n e - W a t e r ......................................... 24
The E f f e c t " , o f R in g S i z e on t h e R e l a t i v eR e a c t i v i t i e s o f Homologous C y c l i c Compounds . . . 41
R a t e C o n s t a n t s f o r N e u t r a l i z a t i o n o f2 - N i t r o p r o p a n e and t l ie Homologous N i t r o c y c l o a l k a n e sw i t h th e Sodium C o n j u g a t e Base o f t h e S o l v e n ta t 0 . 0 0 ° ................................................................................ 60
A c i d D i s s o c i a t i o n C o n s t a n t s o f N i t r o c y c l o a l k a n e si n 33.3% by W e ig h t M et h . ano l -W ate r a t 2 5 . 0 ° . . . . 64
V l l l
TABLES (Continued)
Table Page
12 . R e l a t i v e Rate C o n s t a n t s f o r N e u t r a l i z a t i o n o f N i t r o c y c l o a l k a n e s w i t h t h e Sodium C o n j u g a t e Base o f t h e S o l v e n t a t 0 . 0 0 ° . . . 71
13. R a t e C o n s t a n t s f o r N e u t r a l i z a t i o n o f2 - N i t r o p r o p a n e and t h e Homologous N i t r o c y c l o a l k a n e s w i t h T r i e t h y l a m i n e i n 50% b y Volume 1 , 2 - D i m e t h o x y e t h a n e - U a t e r ....................
1 4 - 3 9 R a t e C o n s t a n t s f rom t h e K i n e t i c E x p e r i m e n t s f o r N e u t r a l i z a t i o n o f 2 - N i t r o p r o p a n e and t h e Homologous N i t r o c y c l o a l k a n e s by th e Sodium C o n j u g a t e Base o f t h e S o l v e n t a t 0 . 0 0 ° . . . ,
4 0 - 4 7 R e p r e s e n t a t i v e K i n e t i c D a t a f o r N e u t r a l i z a t i o n o f 2 - N i t r o p r o p a n e and t h e Homologous N i t r o c y c l o a l k a n e s by t h e Sodium C o n j u g a t e B as e o f t h e S o l v e n t a t 0 . 0 0 ° ..................................................................
4 8 - 5 2 R e p r e s e n t a t i v e D a t a f o r D e t e r m i n a t i o n o ft h e D i s s o c i a t i o n C o n s t a n t s o f t ’ne Homologous N i t r o c y c l o a l k a n e s i n 33.3% by Weight N e t h a n o l - W a t e r a t 2 5 . 0 ° .............................................. ,
89
1 2 9 -1 4 2
1 4 3 , 1 4 51 4 7 , 1 4 91 5 1 , 1 5 31 5 5 , 1 5 7
159 -1 7 4
5 3 . R e p r e s e n t a t i v e D a ta f o r D e u t e r a t i o n o f2 - N i t r o p r o p a n e C a t a l y z e d by T r i e t h y l a m i n e i n D e u te r i u m O x i d e - D i m e t h v l f o r m a m i d e a t 3 8 ' 175
5 4 - 5 9 R a t e C o n s t a n t s f rom Che K i n e t i c E x p e r i m e n t s f o r N e u t r a l i z a t i o n o f 2 - N i t r o p r o p a n e and t h e Homologous N i t r o c y c l o a l k a n e s by T r i e t h y l a m in e i n 50% by Volume 1 , 2 - D i m e t h o x y e t h a n e - W a te r ................................................................................................ 1 77-182
6 0 . R e p r e s e n t a t i v e K i n e t i c D a t a f o r N e u t r a l i z a t i o n o f N i t r o c y c l o h e x a n e by T r i e t h y l a m i n e i n 50% by Volume 1 , 2 - D i m c t h o x y e t h a n e - W a t e r a t 0 . 0 0 ° . , 183
IX
FIGURES
Figure Page
1 . P l o t o f Log k V e r s u s Log k^ a s aF u n c t i o n o f tRe B a s e ......................... 73
2 . P l o t o f Log k^ V e r s u s Log ................................................ 75
3 . P l o t o f Log k^ V e r s u s Log ................................................ 76
4 . C i r c u i t D iag ram o f I n d u s t r i a l I n s t r u m e n t s ,I n c . Model RC-18 C o n d u c t i v i t y B r i d g e ..................................... 99
5 . D iag ram of C o n d u c t i v i t y C e l l Used t o M easu re R e s i s t a n c e o f S o l u t i o n s w i t hLow I m p e d a n c e ................................................................................................ 100
6 . D iag ram o f C o n d u c t i v i t y C e l l Used t o M ea su re R e s i s t a n c e o f S o l u t i o n s w i t hHigh I m p e d a n c e ........................................................................................... 101
7 . P l o t o f K i n e t i c Run 6 0 - I V .......................................................... 144
8 . P l o t o f K i n e t i c Run 6 1 - I V .......................................................... 146
9 . P l o t o f K i n e t i c Run 2 8 - I V ..............................................................' 148
1 0 . P l o t o f K i n e t i c Run 8 2 - I V .......................................................... 150
1 1 . P l o t o f K i n e t i c Run 107 -I V ...................................... 152
1 2 . P l o t o f K i n e t i c Run 1 4 1 - I V ..................................................... 154
1 3 . P l o t o f K i n e t i c Run 14 4-I V . . ...................................... 156
1 4 . P l o t o f K i n e t i c Run 1 9 - I V .......................................................... 158
15 . P l o t o f K i n e t i c Run 5 3 -1 ...................................... 176
1 6 . P l o t o f K i n e t i c Run 2 1 7 - 1 1 ........................... 183
1 7 . P l o t o f t h e Thermod yn amic R e l a t i o nLog k ^ / T V e r s u s 1 / T .............................................................................. 185
X
INTRODUCTION
P r i m a r y and s e c o n d a r y m o n o n i t r o compounds (R^CllNO^) e x i s t
i n t a u t o m e r i c e q u i l i b r i a u i t h t h e i r a c i - n i t r o i s o m e r s , known a s
n i t r o n i c a c i d s (h^C=N00u) . N i t r o compounds a r e p s e u d o - a c i d s
b e c a u s e t h e y r e a c t s l o w l y w i t h s t r o n g b a s e s t o form n i t r o n a t e
a n i o n s (R2C=N02 ) . N i t r o n i c a c i d s a r e much s t r o n g e r a c i d s t h a n
a r e n i t r o compounds and a r e c o n v e r t e d r a p i d l y to n i t r o n a t e s e v e n
by weak b a s e s .
R e a c t i o n o f an a c i d i c m o n o n i t r o compound w i t h a b a s e o c c u r s
by a b i r a o l e c u l a r p r o c e s s s u b j e c t t o g e n e r a l b a s e c a t a l y s i s w h i c h i s
f i r s t o r d e r b o t h i n n i t r o compound and i n b a s e . The r a t e o f n e u t r a l
i z a t i o n o f a n i t r o compound a t a g i v e n t e m p e r a t u r e t h u s d e p e n d s on
i t s s t r u c t u r e , t h e s t r u c t u r e o f t h e b a s e and th e s o l v e n t . The a c i d
s t r e n g t h s o f s im p le n i t r o compounds and t h e i r r a t e s o f n e u t r a l i z a t i o n
a r e n o t c o r r e l a t e d by r e l a t i o n s h i p s o f t h e B r o n s t e d t y p e , a l t h o u g h
t h e i o n i z a t i o n c o n s t a n t s o f s i m p l e n i t r o n i c a c i d s a r e i n t e r p r e t a b l e
on t h e b a s i s of s i m p l e i n d u c t i v e e f f e c t s .
Of p r im e i n t e r e s t t o t h e p r e s e n t r e s e a r c h i s t h e f a c t t h a t
t h e r a t e s o f r e a c t i o n s o f many c a r b o c y c l i c r i n g s y s t e m s may b e
c o r r e l a t e d i n te rm s o f i n t e r n a l s t r a i n a c com pany ing t h e c h a n g e i n
b o n d o r d e r o f a r i n g a t o m . N e u t r a l i z a t i o n o f n i t r o c y c l o a l k a n e s i s
y e t a n o t h e r r e a c t i o n o f t h i s g e n e r a l t y p e . P r e v i o u s work i n t h i s
l a b o r a t o r y h a s e s t a b l i s h e d t h e r e l a t i v e o r d e r f o r n e u t r a l i z a t i o n o f
t h e 4 - t h r o u g h 8 -n e m b e re d n i t r o c y c l o a l k a n e s by h y d r o x i d e i o n
a c c o r d i n g t o E q u a t i o n 1 t o be 4 > > 5 > 1 > 8 ? 6 > > 3 w he re
(CH ) CHNO r e p r e s e n t s a c y c l i c n i t r o compound and (Cil ) C=h’0,2 n / 2 . 2 n ^
(CH ) CH-h'O + Oil (CH ) C=h'0^" + (1 )\ 2 n / 2 \ 2 n
t h e c o r r e s p o n d i n g c y c l o a l k a n e n i t r o n a t e i o n . The r e l a t i v e l y r a p i d
r a t e o f n e u t r a l i z a t i o n o f n i t r o c y c l o b u t a n e i s n o t i n a g r e e m e n t w i t h
p r e s e n t r i n g s t r a i n t h e o r y ; t h e r e a c t i v i t i e s o f t h e h i g h e r n i t r o -
c y c l o a l k a n e homologs do a g r e e i n g e n e r a l w i t h t h a t o f o t h e r s y s t e m s .
The v e r y r a p i d r a t e o f n e u t r a l i z a t i o n o f n i t r o c y c l o b u t a n e h a s b e e n
a t t r i b u t e d t o s o l v a t i o n and bond o p p o s i t i o n e f f e c t s .
N e u t r a l i z a t i o n s o f n i t r o c y c l o a l k a n e s a r e v e r y f a s t r e a c t i o n s
a n d , e v e n u s i n g r a p i d c o n d u c t o m e t r i c t e c h n i q u e s , p r e v i o u s w o r k e r s
h a v e d i s a g r e e d on t h e a b s o l u t e v a l u e s f o r t h e r a t e c o n s t a n t s o f
t h e s e r e a c t i o n s . The m o s t s e r i o u s d i s a g r e e m e n t c o n c e r n s t h e r a t e
c o n s t a n t f o r r e a c t i o n o f n i t r o c y c l o b u t a n e w i t h h y d r o x i d e i o n . I n
g e n e r a l a l l o f t h e p r e v i o u s i n v e s t i g a t o r s do a g r e e t h a t n i t r o c y c l o
b u t a n e i s n e u t r a l i z e d t h e m o s t r a p i d l y b u t t h e v a l u e s o b t a i n e d f o r
t h e r a t e c o n s t a n t a t 0° a r e 2 4 7 , 204 and 165 l . / m . - m i n . The s o u r c e s
o f t h e s e d i f f e r e n c e s seem t o l i e i n t h e m e c h a n i c s o f i n d i v i d u a l
m e t h o d s .
Of f u r t h e r c o n c e r n i s t h e f a c t t h a t n i t r o c y c l o p r o p a n e d o es n o t
u n d e r g o c o n d u c t i v i t y c h a n g e upon e x p o s u r e t o h y d r o x i d e i o n un d e r
c o n d i t i o n s i n which n i t r o c y c l o b u t a n e i s r a p i d l y n e u t r a l i z e d . I t i s
n o t c l e a r w h e t h e r t h e l a c k o f c o n d u c t i v i t y c h a n g e o f t h e n i t r o c y c l o -
p r o p a n e - h y d r o x i d e i o n s y s t c i n i s due t o k i n e t i c o r thermody namic e f f e c t s .
An swer t o t h i s q u e s t i o n w i l l have i m p o r t a n t b e a r i n g on r i n g s t r a i n
t h e o r y a s a p p l i e d t o c y c l o p r o p a n e s wh ich a r e e l c c t r o n e g a t i v e l y s u b
s t i t u t e d .
P r i o r t o t h i s i n v e s t i g a t i o n , t h e i o n i z a t i o n c o n s t a n t s o f t h e
ho m o lo g o u s n i t r o c y c l o a l k a n e s have n o t b e e n d e t e r m i n e d . S i n c e t rie
r a t e s o f n e u t r a l i z a t i o n o f n i t r o m e t l i a n e , n i t r o e t h a n e and 2 - n i t r o -
p r o p a n e do n o t c o r r e l a t e w i t h t h e i r i o n i z a t i o n c o n s t a n t s , i t i s o f
i n t e r e s t t o e x t e n d s u c h s t u d i e s .
T h e r e f o r e , t h e o b j e c t i v e s o f t h e p r e s e n t i n v e s t i g a t i o n a r e t o :
1 . D evelop new t e c h n i q u e s and m e th o d s w h ic h w i l l
e n a b l e a c c u r a t e d e t e r m i n a t i o n o f t h e r a t e
c o n s t a n t s f o r n e u t r a l i z a t i o n o f C^- t h r o u g h C^-
n i t r o c y c l o a l k a n e s .
2 . D e te r m i n e t h e r e l a t i v e r a t e c o n s t a n t s f o r
n e u t r a l i z a t i o n o f r e p r e s e n t a t i v e n i t r o c y c l o -
p r o p a n e s .
3 . S tu d y t h e r a t e s o f n e u t r a l i z a t i o n o f t h e
homologous n i t r o c y c l o a l k a n e s by b a s e s o f
d i f f e r e n t s t r e n g t h s .
4 . D e f i n e more c l e a r l y t h e r o l e o f s o l v e n t i n t h e
n e u t r a l i z a t i o n p r o c e s s e s .
5 . D e t e r m i n e t h e i o n i z a t i o n c o n s t a n t s o f t h e s e n i t r o
com pounds .
6 . A s s e s s t h e e f f e c t o f s t r u c t u r e on t h e r a t e s o f
n e u t r a l i z a t i o n and t h e i o n i z a t i o n c o n s t a n t s o f
t h e 3 - t h r o u g h 8-membered c y c l i c n i t r o compounds ,
7. R e l a t e t h e p r e s e n t r e s u l t s t o t h e g e n e r a l s u b j e c t
o f t h e e f f e c t s of r i n g s i z e and r e a c t i v i t y of
m o n o c y c l i c d e r i v a t i v e s .
HISTORY AI.'D THEORY
S t r u c t u r e a n d R e a c t i v i t y o f A c i d i c N i t r o Compounds
I n t r o d u c t i o n . — N i t r o compounds a r e d e r i v a t i v e s o f h y d r o
c a r b o n s i n w h i c h a n e l e c t r o n e g a t i v e -NO^ g ro u p h a s r e p l a c e d h y d r o g e n
a nd i s b o n d ed t o c a r b o n t h r o u g h n i t r o g e n . N i t r o compounds a r e
r e s o n a n c e h y b r i d s o f t h e f o l l o w i n g , e q u a l l y c o n t r i b u t i n g s t r u c t u r e s :
*1*2*3^-^^ -------- > (2)0 0 -
w h e re R , R and may b e t h e same o r d i f f e r e n t g r o u p s o r h y d r o g e n .
A c i d i c n i t r o compounds ( p r i m a r y and s e c o n d a r y ) e x i s t i n
e q u i l i b r i u m w i t h t h e i r i s o m e r i c f o r m , t h e n i t r o n i c a c i d ( a c i - n i t r o
tcompound) , R^C=N-OH. M o n o n i t r o compounds a r e n o n e l e c t r o l y t e s . They
a r e u s u a l l y d e s c r i b e d a s p s e u d o - a c i d s b e c a u s e t h e y r e a c t s l o w l y and
a t m e a s u r a b l e r a t e s w i t h b a s e s t o fo rm s a l t s w h ic h a r e s t r o n g
e l e c t r o l y t e s . N i t r o n i c a c i d s a r e g e n e r a t e d by a c i d i f i c a t i o n o f
s o l u t i o n s o f s a l t s o f n i t r o compounds a t low t e m p e r a t u r e s . N i t r o n i c
a c i d s a r e g e n e r a l l y u n s t a b l e and r e a r r a n g e t o t h e n i t r o compound.
R e l a t i v e t o n i t r o co m pounds , a c i - n i t r o compounds a r e s t r o n g a c i d s
a n d t h e y a r e n e u t r a l i z e d r a p i d l y by weak b a s e s . U n l i k e t h e i r
i s o m e r i c a n a l o g s , t h e y r e a c t i m m e d i a t e l y , a s do t h e i r s a l t s , w i t h
b r o m i n e o r c h l o r i n e t o y i e l d gem-h a l o n i t r o compounds . N i t r o n i c a c i d s
g i v e t y p i c a l e n o l r e a c t i o n s w i t h f e r r i c c h l o r i d e .
I n t e r m s o f p r e s e n t c o n c e p t s o f b o n d i n g and a c i d - b a s e t h e o r y ,
t h e i n t e r c o n v e r s i o n o f n i t r o compounds and n i t r o n i c a c i d s ca n b e
r e p r e s e n t e d i n t h e e x p r e s s i o n s :
^1 - +R CHNO^ + B ^ . + BH (3 )
^2( N i t r o Compound) ( N i t r o n a t e An ion)
R C=N02 + BH ( = • R^C^NOOH + B (4 )
^ 4 ( N i t r o n i c A c id )
The f i r s t m o n o n i t r o p a r a f f i n s w ere s y n t h e s i z e d f r o m a l k y l
i o d i d e s and s i l v e r n i t r i t e ( 1 ) . E a r l y i n v e s t i g a t i o n s fo und t h a t
( 1 ) V. Meyer a n d 0 . S t u b e r , B e r . , 203 ( 1 8 7 2 ) .
p r i m a r y and s e c o n d a r y n i t r o compounds b e h a v e l i k e weak a c i d s a n d
r e a c t s l o w l y w i t h a q u e o u s a l k a l i t o form s a l t s . I t was s u g g e s t e d (2)
(2 ) A. M i c h a e l , J . p r a k t . Chem. , [ 2 ] , 3]_, 507 ( 1 8 8 8 ) .
s a l t s o f n i t r o com pounds , a n a l o g o u s t o s a l t s o f m a l o n i c and a c e t o -
a c e t i c e s t e r s , w e r e p r o b a b l y p ro d u c e d by c o m b i n a t i o n o f a m e t a l l i c i o n ,
M+, w i t h a n e g a t i v e o x y g e n a tom o f t h e o r g a n i c n i t r o r a d i c a l a c c o r d i n g
to the general structure, R C='IOOM. Observation that salts of nitro2
compounds e x h i b i t p r o p e r t i e s s i m i l a r to s a l t s d e r i v e d f rom s t r o n g
a c i d s , l e d t o t h e p r o p o s a l (3 ) t h a t n i t r o n a t e s a l t s a r e d e r i v e d f rom
(3 ) J . U. N e f , A n n . , 2 7 0 , 330 ( 1 8 9 2 ) .
a t a u t o m e r i c fo rm o f t h e n i t r o compound, R^C=h’OOh, I n d e p e n d e n t
e v i d e n c e was o b t a i n e d ( 4 , 5 , 6 ) t h a t a r y l a l k y l n i t r o m e t h a n e s e x i s t i n
(4 ) A. F . H o l l e n a n , R ec . t r a v . c h i m . , _1^, 356 ( 1 8 9 6 ) .
(5) A. H a n t c s c h and 0 . U. S c h u l t z e , i b i d . , 1 5 , 699 ( 1 8 9 6 ) .
(6) M. K o n o v a l o f f , i b i d . , 1 5 , 2193 ( 1 8 9 6 ) .
two i s o m e r i c m o d i f i c a t i o n s . K o l l e n a n p r o p o s e d the" e x i s t e n c e o f an
a c i - n i t r o t a u t o i n e r , R2C=R00H ( i d e n t i c a l t o t h a t p o s t u l a t e d by K e f ) ,
w h i c h i s o m e r i z e s a t a m e a s u r a b l e r a t e t o t h e n i t r o s t r u c t u r e .
I t i s now w e l l e s t a b l i s h e d t h a t p r i m a r y and s e c o n d a r y n i t r o
compounds (R^CHXO^) e x i s t i n e q u i l i b r i u m w i t h a t a u t o m e r i c fo r m ,* T
t h e i s o m e r i c n i t r o n i c a c i d (R C=N-0[I).2
Mechan ism of N e u t r a l i z a t i o n - D e v e lo p m e n t o f The o r y . — Sem i-
q u a n t i t a t i v e k i n e t i c m e a s u r e m e n t s (7) o f t h e h y d r o x i d e i o n c a t a l y z e d
(7) A. H a n t z s c h , B e r . , 32 , 575 ( 1 8 9 9 ) .
t a u t o m e r i z a t i o n ( o r n e u t r a l i z a t i o n ) o f n i t r o e t h a n e ( f o r w a r d p r o c e s s
o f E q u a t i o n 3) u s i n g c o n d u c t o m e t r i c t e c h n i q u e s (8) d e m o n s t r a t e d t h e
( 8 ) Hol lem an had o b s e r v e d e a r l i e r t h a t t h e c h a n g e s f rom n i t r o compound to n i t r o n a t e i o n ( a c i - a n i o n ) o r f rom n i t r o n i c a c i d ( a c i - n i t r o compound) t o n i t r o compound c o u l d b e f o l l o w e d by t h e c h a n g e i n e l e c t r i c a l c o n d u c t i v i t i e s o f the. r e a c t i n g s o l u t i o n s ;A. F . H o l l e m a n , Rec . t r a v . c h i m . , 14 , 121 ( 1 8 9 5 ) .
r e a c t i o n was t im e d e p e n d e n t . On t h i s b a s i s , n i t r o e t h a n e was
c l a s s i f i e d as a " p se u d o a c i d " . I t was b e l i e v e d t h a t t h e s e " p s e u d o
a c i d s " f i r s t u n d e r g o i n t e r n a l r e a r r a n g e m e n t t o t h e i r " t r u e a c i d "
fo r m s b e f o r e r e a c t i n g w i t h a b a s e . U s in g mod ern s t r u c t u r e , t h i s
i d e a i s e x p r e s s e d a s ;
R c i i n o ------------) R c=:;oou s l o w (5)2 2 2
+R^C^NOOH + B > + BH f a s t (6)
The r a t e s o f b r o m i n a t i o n o f 2 - n i t r o p r o p a n e , n i t r o m e t h a n e ,
b r o m o n i t r o m e t h a n e , and d i b r o i n o n i t r o i n e t h a n e w e r e d e t e r m i n e d (9) i n
( 9 ) R. J u n e l l , Z. p h y s i k . Chem. , A 141 , 71 (1 9 2 0 ) .
a q u e o u s h y d r o b r o m i c and h y d r o c h l o r i c a c i d s . I t was fo u n d t h a t r a t e s
o f b r o m i n a t i o n a r e i n d e p e n d e n t o f t h e c o n c e n t r a t i o n s o f h a l o g e n b u t
a r e f i r s t o r d e r w i t h r e s p e c t t o c o n c e n t r a t i o n o f n l t r o p a r a f f i n .
The s t u d i e s o f J u n e l l w e r e e x t e n d e d (10 ) by d e t e r m i n i n g t h e
( 1 0 ) K. J . P e d e r s o n , K g l . Danske V i d e n s k a b . S e l s k a b , M a t h . - f y s . M ed d . , 1 2 , No. 1 ( 1 9 3 2 ) .
r a t e s o f b r o m i n a t i o n of n i t r o m e t h a n e i n w a t e r and i n b u f f e r e d
s o l u t i o n s c o n t a i n i n g v a r i o u s b a s i c a n i o n s . T h i s s t u d y c o n t r i b u t e d
some i m p o r t a n t new i d e a s f o r t h a t t i m e : ' t h e r a t e s o f b r o m i n a t i o n
a r e t h e same i n w a t e r a s i n h y d r o b r o m i c a c i d ( t h i s s t r o n g l y s u g g e s t s
t h a t a c i d c a t a l y z e d t a u t o m e r i s m d o e s n o t o c c u r ) ; t h e r a t e s a r e f i r s t
o r d e f ^ i n b a s e and f i r s t o r d e r i n n i t r o compound; u n d i s s o c i a t e d a c i d s
h a v e no e f f e c t ; t h e r a t e s a r e d e p e n d e n t on t h e s t r e n g t h of t h e b a s e
a c c o r d i n g t o t h e manner o u t l i n e d i n t h e r e c e n t l y d e v e l o p e d t h e o r y
o f c a t a l y s i s ( 1 1 ) .
( 1 1 ) J . N. B r o n s t e d , Chem. R e v . , _5, 231 ( 1 9 2 8 ) .
The mecha n i sm a d v a n c e d by P e d e r s o n i s :
^1 - +RgCHNOg + B ^RgCNO + BH s lo w (7)
k _RgCNOg ^ RgC = NOg f a s t (8)
i n w h i c h k 2 > > k ^ . T h i s m ech a n i sm r e q u i r e s o n l y i n c o r p o r a t i o n o f
m odern c o n c e p t s o f r e s o n a n c e t h e o r y t o be e q u i v a l e n t t o t h e f o r w a r d
p r o c e s s o f E q u a t i o n 3 . As a r e s u l t of t h i s w o rk , t h e t h e o r y t h a t
10
n e u t r a l i z a t i o n o f a n i t r o compound o c c u r s by a t t a c k o f t h e b a s e on
t h e t r u e n i t r o compound was p l a c e d on a f i r m e x p e r i m e n t a l b a s i s .
S h o r t l y a f t e r w a r d , t h e k i n e t i c s o f r e a c t i o n o f n i t r o e t h a n e i n
h y d r o b r o m i c a c i d we re s t u d i e d ( 1 2 ) . I t h a d b e e n shown ( 1 3 , 1 4 ) t h a t
(1 2) R. J u n e l l , A r k i v Kemi, No. 27 ( 1 9 3 4 ) .
(1 3) V. Meyer and J . L o c h e r , A n n . , 1 8 0 , 163 (1 3 7 6 ) .
(14) E. B am b erg e r and E. R u s t , i b i d . , 3 5 , 45 (1 9 0 2 ) .
p r i m a r y n i t r o a l k a n e s a r e i s o m e r i z e d by m i n e r a l a c i d s t o h y d r o x a m i c
a c i d s and t h e n h y d r o l y z e d t o h y d r o x y l a m i n e and c a r b o x y l i c a c i d s ,
p r o b a b l y a c c o r d i n g t o t h e mechani sm p r o p o s e d i n E q u a t i o n 9 ( 1 5 , 1 6 ) .
HCl H + O" " 2 ° HRCH NO --------> RClI=NO^Ii > R-C-N > R-C-N=0
2 2 2 - I -0 1 1 Oil ClH
+H 0 2
R-C=NOH ------------> R-C=MOH--------> ROD H + H NOHCl on 2
( h y d r o x a m ic a c i d ) (9)
(15) C. D. N e n i t z e s c u and ü . A. I s a c e s c u , B u l l . Soc . Chim. R o m an ia , 1 4 , 53 ( 1 9 3 2 ) .
(16) II. B. H a ss and E. F. R i l e y , Chem. R e v . , 32, 373 ( 1 9 4 3 ) .
11
S i n c e t h e c o n d i t i o n s f o r i s o m e r i z a t i o n and h y d r o l y s i s o f n i t r o e t h a n e
a r e s i m i l a r t o t h o s e f o r n e u t r a l i z a t i o n , i t was p o s s i b l e t o d e t e r m i n e
( 1 7 ) t h e r a t e o f f o r m a t i o n o f e th a n e h y d r o x a m i c a c i d o r h y d r o x y l a m i n e
(17) R. J u n e l l , A r k i v . Kemi, I I G , No. 30 ( 1 9 3 4 ) .
f r o m n i t r o e t h a n e i n h y d r o c h l o r i c a c i d . • The r a t e c o n s t a n t found f o r
i s o m e r i z a t i o n and h y d r o l y s i s o f n i t r o e t h a n e i s a l m o s t i d e n t i c a l to
t h a t o f b r o m i n a t i o n o f n i t r o e t h a n e . Q u a n t i t a t i v e b r o m i n a t i o n e x p e r i
m e n t s showed t h a t no e t h a n e h y d r o x a m i c a c i d i s f o r m e d i n t h e p r e s e n c e
o f b r o m i n e . The r e s u l t s d e f i n i t e l y i n d i c a t e t h a t b r o m i n a t i o n of
n i t r o e t h a n e and f o r m a t i o n o f e t h a n e h y d r o x a m i c a c i d f r om n i t r o e t h a n e
p r o c e e d f rom t h e same i n t e r m e d i a t e , t h e n i t r o n a t e a n i o n ( a c i an io n )
o f t h e n i t r o n i c a c i d .
The e a r l y d e v e l o p m e n t o f ou r p r e s e n t i d e a s a b o u t t h e s t r u c t u r e
o f n i t r o compounds , t h e i r t a u t o m e r i c forms and t h e i r a c i d - b a s e -
c a t a l y z e d t a u t o m e r i z a t i o n h a s been r e v ie w e d i n more d e t a i l ( 1 6 , 1 8 , 1 9 ) .
(18) H. S t o n e , P h . D . d i s s e r t a t i o n . The Ohio S t a t e U n i v e r s i t y ,1 9 5 0 .
(19) P . W. K. F l a n a g a n , i b i d . , 1957.
R a t e s o f N e u t r a l i z a t i o n - E f f e c t s o f S t r u c t u r e , S o l v e n t and
D e u t e r i u m I s o t o p e . — R a t e s o f n e u t r a l i z a t i o n o f s i m p l e a c y c l i c n i t r o
12
com pounds by h y d r o x i d e i o n h a v e b een s t u d i e d b y s e v e r a l i n v e s t i g a t o r s
( 2 0 , 2 1 , 2 2 , 2 3 , 2 4 ) . The r e s u l t s o f t h e s e i n v e s t i g a t i o n s a r e co m p i l ed
(2 0 ) R. J u n e l l , A r k i v . Kemi, I I B , No. 34 ( 1 9 3 4 ) .
(21 ) R. J u n e l l , d i s s e r t a t i o n , U p p s a l a , 1 9 3 5 .
(2 2) S. 11. H a ro n an d V. K. La H er , J . Am. Chem. S o c . , 6 0 ,2588 (1938) .
(2 3 ) P . J . L i v i n g a n d J . L a k r i t z , i b i d . , 11_, 3217 (1 9 5 5 ) .
(24) J . G. Trayn l ia m, u n p u b l i s h e d r e s e a r c h , Tiie Ohio S t a t eU n i v e r s i t y , 1952.
i n T a b l e s 1 and 2 . The d a t a a r e c o r r e l a t e d on t h e b a s i s o f i n d u c t i v e
an d s t e r i c f a c t o r s o p e r a t i v e i n t h e n i t r o co m p o u n d s . R a t e s o f
n e u t r a l i z a t i o n o f s u b s t i t u t e d 1 - p h c n y l n i t r o e t h a n e s h a v e a l s o been
i n v e s t i g a t e d ( 2 5 ) . R e s u l t s o f t h i s s t u d y a r c c o m p i l e d i n T a b l e 8
(2 5 ) M. Fukuyama, u n p u b l i s h e d r e s e a r c h . Th e Oh io S t a t e U n i v e r s i t y , 1962.
an d w i l l b e d i s c u s s e d i n t h e s e c t i o n , I o n i z a t i o n C o n s t a n t s and
B r o n s t e d C o r r e l a t i o n s f o r N i t r o Compounds. The k i n e t i c s o f r e a c t i o n s
o f h y d r o x i d e i o n and n i t r o c y c l o a l k a n e s h ave b e e n d e t e r m i n e d i n t h i s
l a b o r a t o r y ( 1 8 , 1 9 , 2 4 ) . Th e r e s u l t s o f t h e s e s t u d i e s a r e c o m p i l e d i n
T a b l e 9 and w i l l b e d i s c u s s e d i n the s e c t i o n . F a c t o r s A f f e c t i n g
R e a c t i v i t i e s i n C y c l i c S y s t e m s .
13
TABLE 1
RATE CONSTANTS FOR NEUTRALIZATION OF NITROALKANES BY SODIUM HYDROXIDE IN WATER
( l . / m . - m i n .
Compound 0 * ( 2 0 , 2 1 ) 0° (22)
)
2 5 ° ( 2 3 )
N i t r o m e t h a n e 173 238 1026N i t r o e t h a n e 3 5 . 2 39 .1 2361 - N i t r o p r o p a n e 2 9 . 2 1952 - N i t r o p r o p a n e 1 . 9 4 2 .0 8 1 6 . 41 - N i t r o b u t a n e 1922 - N i t r o b u t a n e 8 . 8
TABLE 2
RATE CONSTANTS FOR NEUTRALIZATION OFNITROALKANES BY SODIUM HYDROXIDE IN
50% BY VOLUME 1,4-DIOXANE-WATER AT 0 ° ( 2 4 )
Compound ( 1 . / m . - m i n . )
2 - N i t r o p r o p a n e 8 . 0 32 - N i t r o b u t a n e 3 . 8 22 - N i t r o p e n t a n e 2 . 7 83 - N i t r o p e n t a n e 1 . 6 94 - N i t r o h e p t a n e 0 . 7 1 32 , 2 - D i m e t h y 1 - 3 - n i t r o b u t a n e 0 . 0
14
The r a t e o f n e u t r a l i z a t i o n o f n i t r o e t h a n e by so d iu m h y d r o x i d e
i n m i x t u r e s o f m e t h a n o l - w a t e r (22.77% by w e i g h t w a t e r ) , (26) i s much
(26) R, P. B e l l and A. D. N o r r i s , J . Chem. S o c . , 854 ( 1 9 4 1 ) .
g r e a t e r t h a n t h e c o r r e s p o n d i n g r a t e i n p u r e w a t e r ( 2 2 ) . The e f f e c t
o f s o l v e n t c o m p o s i t i o n on t h e r a t e o f r e a c t i o n o f 2 - n i t r o p r o p a n e
w i t h h y d r o x i d e i o n ( i n m i x t u r e s o f 1 , 4 - d i o x a n e - w a t e r ) h a s b e e n
i n v e s t i g a t e d (T a b le 3) by Trayn'narn (2 4 ) . I n g e n e r a l , a d e c r e a s e i n
t h e i o n - s o l v a t i n g power o f t l i e medium i n c r e a s e s t h e r a t e o f n e u t r a l
i z a t i o n o f 2 - n i t r o p r o p a n c . T h i s r e s u l t i s i n a g r e e m e n t w i t h q u a l i
t a t i v e t h e o r y o f s o l v e n t e f f e c t s ( 2 7 ) . A c c o r d i n g t o t h i s t h e o r y .
(27 ) E. Ü. Hughes and C. K. I n g o l d , J . Chem. S o c . , 244( 1 9 3 5 ) .
a n i n c r e a s e i n t h e i o n - s o l v a t i n g power o f t h e medium w i l l a c c e l e r a t e
t h e c r e a t i o n and c o n c e n t r a t i o n o f c h a r g e and i n h i b i t i t s d e s t r u c t i o n
a n d d i f f u s i o n .
I o n - s o l v a t i n g po wer i s d e f i n e d (27) a s t h e i o n i z i n g power o f
t h e s o l v e n t and as (28) t h e s p e c i f i c i n t e r a c t i o n b e t w e e n s o l v e n t
(2 8 ) J . H ine , " P h y s i c a l O r g a n i c C h e m i s t r y " , M cG raw -H i l l Book C o . , I n c . , New Y o rk , N . Y . , 1962 , pp . 3 9 -4 0 .
15
TABLE 3
RATE CONSTANTS FOR NEUTRALIZATION OF2-NITR0PR0PA1Œ BY SODIUll HYDROXIDE AT 0 “ AS A FUNCTION OF SOLVENT COMPOSITION (24)
S o l v e n t k g , 0 °^b
AH*c
AS*
W a te r 2 .3 1 4 . 6 - 1 1 . 5
90 W a t e r / 1 0 d i o x a n e 2 .8 6 1 4 . 1 - 1 2 . 9
70 W a te r / 3 0 d i o x a n e 5 .0 6 1 3 . 0 - 1 5 . 5
50 W a te r / 5 0 d i o x a n e 8 .0 3 1 3 . 1 - 1 4 . 4
30 W a te r / 7 0 d i o x a n e 1 1 . 4 1 2 . 4 - 1 6 . 4
( 1 . / m . - n i i n . )
^ A H * ( k c a l . / m o l e )
^ A S * ( c a l . / m o l e - d e g . )
16
i n t e r a c t i o n b e t w e e n s o l v e n t m o l e c u l e s and t h e d i s s o l v e d i o n s . The
a t t r a c t i o n o f a c h a r g e f o r a d i p o l e m us t a c c o u n t f o r p a r t o f t h i s
i n t e r a c t i o n . T h e r e f o r e , a n h y d r o x i d e i o n w o u ld b e e x p e c t e d t o a t t r a c t
t h e p o s i t i v e end o f a p o l a r s o l v e n t m o l e c u l e . I n aq u e o u s med ia t h i s
s o l v a t i o n i n t e r a c t i o n i s a t y p e o f h y d r o g e n b o n d i n g .
I n t h e r e a t i o n s e q u e n c e s t u d i e d by T ra y n h am , t h e c h a r g e ,
l o c a l i z e d on t h e h y d r o x i d e i o n i n t h e g r o u n d s t a t e , becomes d i s p e r s e d
o v e r a somewhat l a r g e r vo lum e i n t h e t r a n s i t i o n s t a t e . I f t h e c h a r g e
d e n s i t y d i m i n i s h e s i n t h e t r a n s i t i o n s t a t e , t h e d e g r e e o f s o l v a t i o n
d e c r e a s e s . T h i s p i c t u r e i s c o n s i s t e n t w i t h t h e t r e n d o f t h e a c t i v a t i o n
p a r a m e t e r s ( T a b l e 3) w h i c h s u g g e s t t h a t t h e r e a c t a n t s a r e more s o l v a t e d
t h a n t h e t r a n s i t i o n s t a t e . The d e c r e a s e i n t h e e n t h a l p y o f a c t i v a t i o n
w i t h a d e c r e a s e i n t h e i o n - s o l v a t i n g a b i l i t y o f t h e medium ( i n c r e a s e
i n p e r c e n t 1 , 4 - d i o x a n e ) , i n d i c a t e s t h a t t h e h y d r o x i d e i o n i s l e s s
s o l v a t e d i n t h e g ro u n d s t a t e t h u s i n c r e a s i n g t h e e n e r g y o f t h e g r o u n d
s t a t e and l o w e r i n g t h e e n t h a l p y o f a c t i v a t i o n . The d e c r e a s e i n t h e
a c t i v a t i o n e n t r o p y (becom es more n e g a t i v e ) a s t h e s o l v e n t p o l a r i t y
d e c r e a s e s may b e i n t e r p r e t e d to i n d i c a t e t h a t t h e s y s t e m a c q u i r e s a
g r e a t e r d e g r e e o f o r i e n t a t i o n i n t h e t r a n s i t i o n s t a t e r e l a t i v e t o a
g r o u n d s t a t e i n w h ich t h e h y d r o x i d e i o n i s l e s s s o l v a t e d .
Some i n s i g h t i n t o t h e n a t u r e o f t h e t r a n s i t i o n s t a t e f o r
n e u t r a l i z a t i o n o f n i t r o compounds h a s b e e n o b t a i n e d f rom s t u d i e s o f
17
d e u t e r i u m i s o t o p e e f f e c t s . R a t e c o n s t a n t s h a v e b e e n d e t e r m i n e d f o r
n e u t r a l i z a t i o n o f n i t r o m e t h a n e and t r i d e u t e r o n i t r o m e t h a n e by a c e t a t e
a n d by c h l o r o a c e t a t e i o n s ( 2 8 , 2 9 ) and f o r n e u t r a l i z a t i o n o f n i t r o -
(28) 0 . R e i t z , Z. p h y s i k . Chem. , A 176 , 363 ( 1 9 3 6 ) .
(29) Û. R e i t z , Z. b l e k t r o c l i e m . , 582 ( 1 9 3 6 ) .
c y c l o b u t a n e , 1 - d - n i t r o c y c l o b u t a n e , n i t r o c y c l o p e n t a n e , 1 - d - n i t r o c y c l o -
p e n t a n e , n i t r o c y c l o h e x a n e and 1 - d - n i t r o c y c l o h e x a n e by h y d r o x i d e i o n
( 1 9 , T a b l e 5 ) . The r a t i o o f t h e r a t e c o n s t a n t f o r n e u t r a l i z a t i o n o f
t h e u n d e u t e r a t e d n i t r o c y c l o a l k a n e , k , t o t h e r a t e c o n s t a n t f o r i t s
d e u t e r a t e d a n a l o g , l y , i s c l o s e t o t h e a p p r o x i m a t e maximum v a l u e s
( T a b l e 4) f o r k i n e t i c i s o t o p e e f f e c t s ( 3 0 ) . I t was p r o p o s e d (19)
(30) H i n e , p . 72.
t h a t , i n t h e t r a n s i t i o n s t a t e f o r n e u t r a l i z a t i o n of n i t r o c y c l o -
a l k a n e s , t h e c a r b o n - h y d r o g e n bond i s p r o b a b l y h i g h l y b r o k e n a nd t h e
b o n d b e t w e e n t h e p r o t o n and t h e h y d r o x i d e i o n i s i n t h e v e r y e a r l y
s t a g e s o f f o r m a t i o n .
OU
^ 2
18
TABLE 4
APPROXIMATE îL'vXIMUM VALUES FOR K IN ETIC ISOTOPE EFFECTS
T°CV - o
R e f e r e n c e
0 8 .2 3010 7 . 7 1925 6 . 9 3 0 , 3 170 5 . 4 19
100 4 . 6 30200 3 . 4 31500 2 . 1 3 0 , 3 1
TABLE 5
DEUTERIUM ISOTOPE EFFECTS IN NEUTRALIZATION OF NITROCYCLOALKANES
BY SODIUM HYDROXIDE (19)
0° 10° 28°
E f f e c t o f i s o t o p i c chang e on t h e a c t i v a t i o n
p a r a m e t e r s
(AH*) (AS*)
N i t r o c y c l o b u t a n e 8.5 8.3 7 .3 0 . 8 - 1 . 3N i t r o c y c l o p e n t a n e 8 .3 7 .6 6.8 1 . 1 - 0 . 1N i t r o c y c l o h e x a n e 8 .9 8 . 0 6 .7 1 . 5 + 1 . 2A p p r o x i m a t e
maximum v a l u e s 8 .2 7 .7 6 .9 1 . 1 5 0
R e f e r e n c e s (30) (19 ) (30)
19
The i n t e r p r e t a t i o n o f t h e "maximum" i s o t o p e e f f e c t h a s b e e n
s u b j e c t t o some a l t e r a t i o n s i n c e i t was f i r s t p r o p o s e d ( 3 1 ) . More
r e c e n t c o n s i d e r a t i o n s (32) p o i n t o u t t h a t t h e o r i g i n a l p r o p o s a l c o n
f l i c t s w i t h t h e t h e o r y o f a b s o l u t e r e a c t i o n r a t e s ( 3 3 ) . I t a l s o
(31) K. B. U i b e r g , Chem. R e v . , 713 ( 1 9 5 5 ) .
(32) F. H. V /e s th e im er , i b i d . . 6_1, 265 ( 1 9 6 1 ) .
(33) S. G l a d s t o n e , K. J . L a i d l e r , and H. F y r i n g , "TheT h e o r y o f R a t e P r o c e s s e s " , McG raw -Hil l Book C o . , I n c . , Hew York ,New York , 1941 .
s u f f e r s t h e i n a b i l i t y t o , a t l e a s t , q u a l i t a t i v e l y a c c o u n t f o r k / k ^
v a l u e s g r e a t e r t h a n t h e p r e d i c t e d maximum o r t o a c c o u n t f o r low
v a l u e s o f k / k .II D
P r e v i o u s l y , t h e o b s e r v e d v a l u e o f k^^/k^ was c o n s i d e r e d (31)
t o dep end on t h e d i f f e r e n c e i n z e r o - p o i n t e n e r g i e s o f t h e r e a c t a n t s ,
(C -H ,C -U ), and t h e d e g r e e o f bond b r e a k i n g i n t h e t r a n s i t i o n s t a t e .
I t i s now r e c o g n i z e d ( 3 0 , 3 2 ) , k / k d ep e n d s on t h e d i f f e r e n c e s i nH D
z e r o - p o i n t e n e r g i e s o f t h e r e a c t a n t s and t h e t r a n s i t i o n s t a t e s .
T h u s , a p p r o x i m a t e maximum i s o t o p e e f f e c t s s h o u l d b e o b s e r v e d when,
i n t h e t r a n s i t i o n s t a t e f o r n e u t r a l i z a t i o n , t h e p r o t o n o r d e u t e r o n
i s b onded w i t h e q u a l s t r e n g t h t o t h e c a r b o n and t o t h e b a s e . I n
s u c h a c a s e , t h e z e r o - p o i n t e n e r g i e s o f t h e two a c t i v a t e d com plexes
a r e e q u a l and t h e a p p r o x i m a t e maximum v a l u e o f k ^ / k ^ a r i s e s t h r o u g h
d i f f e r e n c e s i n z e r o - p o i n t e n e r g i e s o f t h e r e a c t a n t s .
20
A c i d i c N i t r o Compounds a s R e f e r e n c e A c i d s . — M i t r o e t h a a e h a s
b e e n u s e d a s a model i n a c i d - b a s e r e a c t i o n s b e c a u s e i t i s n e u t r a l i z e d
a t c o n v e n i e n t r a t e s by v a r i o u s b a s e s t o fo r m t h e s t a b l e e t h a n e -
n i t r o n a t e a n i o n . The r a t e s o f r e a c t i o n b e t w e e n n i t r o e t h a n e and a
s e r i e s o f amine and p y r i d i n e b a s e s have b e e n i n v e s t i g a t e d ( 3 4 , 3 5 , 3 6 ) .
(34) R. G. P e a r s o n , J . Ar.i. Chem. S o c . , 10, 204 ( 1 9 4 8 ) .
(35) R. G. P e a r s o n and F. V. W i l l i a m s , i b i d . , 7 5 , 3073 ( 1 9 5 3 ) .
(35) R, G. P e a r s o n and F. V. W i l l i a m s , i b i d . , 7 6 , 253 ( 1 9 5 4 ) .
I t was found t h a t D r o n s t e d r e l a t i o n s h i p s b e t w e e n t h e r a t e s o f
n e u t r a l i z a t i o n and t h e i o n i z a t i o n c o n s t a n t o f t h e b a s e h o l d e x c e p t
f o r s t e r i c a l l y h i n d e r e d b a s e s . I n t h e s e c a s e s s i g n i f i c a n t d e v i a t i o n s
o c c u r .
C o n v e r s i o n o f n i t r o e t h a n e t o i t s i o n by v a r i o u s am ines an d t h e
r e t r o g r a d e a c i d c a t a l y z e d n e u t r a l i z a t i o n o f t h e a n i o n h a s b e e n
s t u d i e d ( 3 7 ) . Both t h e b a s e - c a t a l y z e d and t h e a c i d - c a t a l y z e d p r o c e s s e s
(37) li . J . G r e g o r y and I . C. B r u i c e , i b i d . , 8 9 , 2327 ( 1 9 6 7 ) .
a r e c o r r e l a t e d by B r o n s t e d e q u a t i o n s f o r g e n e r a l - a c i d and b a s e
c a t a l y s i s . Hoi /ever , t h e l o g s o f t h e r a t e c o n s t a n t s f o r r e a c t i o n s o f
t h e t e r t i a r y , s e c o n d a r y , a n d p r i m a r y am ines l i e on s e p a r a t e B r o n s t e d
p l o t s o f p a r a l l e l s l o p e . The s e p a r a t e p l o t s a r e p r e s u m a b ly du e t o
d i f f e r e n c e s o f s o l v a t i o n ( 3 7 ) .
21
N i t r o c y c l o h c x a n e s h a v e a l s o s e r v e d a s r e f e r e n c e a c i d s t o
s t u d y v a r i o u s e f f e c t s . F o r e x a m p le , B o r d w e l l an d V e s t l i n g (38)
(38) F . G. B o r d w e l l and M. H. V e s t l i n g , J . Am. Chem. S o c . , 89, 3906 (1967).
h a v e u s e d s u b s t i t u t e d n i t r o c y c l o h e x a n e s t o d e m o n s t r a t e s t e r i c
h i n d r a n c e t o t h e f o r m a t i o n o f and p r o t o n a t i o n o f t h e n i t r o n a t e i o n
o f 2 - a r y l - l - n i t r o c y c l o h e x a n e s . t r a n s - 2 - A r y l - l - n i t r o c y c l o h e x o n e s
w e r e f o u n d to r e a c t 22 t o 44 t i m e s s l o w e r w i t h so d iu m m e th o x id e i n
m e t h a n o l a t 25° t h a n do t h e c i s i s o m e r s .
l o n i z a t i o n C o n s t a n t s a nd Bro n s t e d Cor r e ] a t i o n s f o r A c i d i c
Ni t r o Compound s . — The e q u i l i b r i a i n v o l v i n g n i t r o a l k a n e s , a l k a n o -
n i t r o n a t c s , and n i t r o n i c a c i d s a r e su m m ari zed by t h e f o l l o w i n g
e x p r e s s i o n ( E q u a t i o n 3 p l u s E q u a t i o n 4) :
k l k_R„ CHNO + B R C=NO„ + Bl I — R C=NOOH + B
2 2 ^ 2 2 ^ 2 kg k
( 10)
w h e r e t h e i o n i z a t i o n c o n s t a n t o f t h e n i t r o compound i s K = k / k ,N 1 2
an d t h e i o n i z a t i o n c o n s t a n t o f t h e n i t r o n i c a c i d i s K = k ^ / k .a c i 3 4
E q u a t i o n 10 i s b a s e d on t h e c o n c e p t o f m i c r o s c o p i c r e v e r s i b i l i t y .
I f b a s e - c a t a l y z e d t a u t o r a e r i z a t i o n of n i t r o compounds i s s u b j e c t to
g e n e r a l - b a s e c a t a l y s i s t h e n , i n p r i n c i p l e , t h e c o n v e r s i o n o f a
n i t r o n a t e a n i o n t o a n i t r o compound w i l l e x h i b i t g e n e r a l - a c i d
c a t a l v s i s .
22
E a r l y i n t h e s t u d i e s o f a c i d and b a s e r e a c t i o n s o f n i t r o
c o m p o u n d s , e x p e r i m e n t a l v a l i d i t y o f t h i s p r i n c i p l e w as d e m o n s t r a t e d
by J u n e l l ( 3 9 ) . The r e c o m b i n a t i o n o f a l k a n e n i t r o n a t c i o n s w i th
p r o t o n d o n o r s has a l s o b e e n i n v e s t i g a t e d by Maron and La Her (40)
a n d b y P e a r s o n and D i l l o n ( 4 1 ) .
(3 9) R. J u n e l l , S v e n s k Kara. T i d , , 125 ( 1 9 3 4 ) .
(4 0) S. H. M ar on and V. K. La Mer , J . Am. Chem. S o c . , 6nL, 692 ( 1 9 3 9 ) .
(41 ) R. G. P e a r s o n an d R. L. D i l l o n , i b i d . , 72 , 3574( 1 9 5 0 ) .
The i o n i z a t i o n c o n s t a n t s , K , o f a nu m b er o f n i t r o a l k a n e sN
a n d a c i - n i t r o a l k a n e s , h a v e bee n d e t e r m i n e d ( 2 5 , 4 2 , 4 3 , 4 4 ) .
(42) D. T u r n b u l l a n d S. H. Maron, i b i d . , 6 ^ , 212 (19 43 ) .
( 43 ) G. W. Ell e l a n d a n d J . F a r r , i b i d . , 6 5 , 1433 (1943) .
(44) N. K orn b lu ra , R. Blackwood and J . P o w e r s , i b i d . ,79_, 2508 ( 1 9 5 7 ) .
T h e s e d a t a a r e s u m m a r i z e d i n T a b l e s 6 , 7 and 8 . I t i s o f i n t e r e s t
t h a t t h e r a t i o o f n i t r o compound to n i t r o n i c a c i d i s g i v e n by
( f ro m E q u a t i o n 1 0 ) a n d , t h e r e f o r e , i s i n d e p e n d e n t o f t h e pH
o f t h e s y s t e m . From t h e v a l u e s f o r K . and K i n T a b l e 6 , t h ea c i N
r a t i o i s a b o u t 4 0 0 /1 an d 1 0 , 0 0 0 / 1 f o r 2 - n i t r o p r o p a n e and n i t r o e t h a n e ,
r e s p e c t i v e l y . T h e r e f o r e , i n d e t e r m i n i n g t h e r a t e s o f n e u t r a l i z a t i o n
23
TABLE 6
IONIZATION CONSTANTS OF NITROALKANES AND NITRONIC ACIDS IN WATER AT 25 °
Compound (4 2 ) (43)
P * a c i
(2 1 ) (42)
N i t r o m e t h a n e 1 0 . 2 1 1 0 . 2 4 3 . 2 5 3 .6 4N i t r o e t h a n e 8 . 4 6 8 .6 0 4 . 4 11 - N i t r o p r o p a n e 8 . 9 82 - N i t r o p r o p a n e 7 . 6 8 7 . 7 - 7 . 8 5 . 1 1
TABLE 7
IONIZATION CONSTANTS OF NITROALKAIŒS IN 50% AQUEOUS ETUA1\0L (44 )
Compoundp " n
1 - N i t r o b u t a n e 102 - N i t r o b u t a n e 9 . 4Pheny I n i t ro ine t h a n e 8 . 2
24
TABLE 8a
RATE CONSTANTS FOR NEUTRALIZATION AID IONIZATION CONSTANTS OF META- AND PARA-SUBSTITUTEU 1-PHENYLNITRUETlLANES IN
50% BY VOLUME 1 , 4-ÜIONANE-WATER (25)
S u b s t i t u e n t k , 0 ° ( l . / m , - m i n . ) pK (3 0° )2 N
p-Cil 5 4 .2 • 1 0 .4 7 J
m-CH„ 60 .6 1 0 . 5 3— J
H 84.2 1 0 .1 5
n-CH^O 9 1 .2 1 0 . 3 3
p - C l 307 9 . 8 1
p - B r 307 1 0 .0 0
m-Br 386 9 . 9 3
m-NO„ 1873 ' 9 . 1 8— 2
p-NOg 3150 9 .0 6
aB a s e : Sodium h y d r o x i d e
25
o f m o s t n i t r o compounds i n w a t e r t h e c o n c e n t r a t i o n o f n i t r o n i c a c i d
may b e n e g l e c t e d .
The i o n i z a t i o n c o n s t a n t s f o r n i t r o n i c a c i d s e> :h ib i t t h e
e x p e c t e d a c i d - w e a k e n i n g , e l e c t r o n - d o n a t i n g i n d u c t i v e e f f e c t s o f
m e t h y l g r o u p s as o b s e r v e d i n s u b s t i t u t i o n o f m e t h y l g ro u p s i n t h e
a l p h a - p o s i t i o n o f c a r b o x y l i c a c i d s ( 4 2 ) . However , i n n i t r o n i c a c i d s ,
t h e e f f e c t i f much more p r o n o u n c e d . F o r e x a m p l e , a c i - n i t r o e t h a n c
i s a 5 - f o l d s t r o n g e r a c i d t h a n a c i - 2 - n i t r o p r o p a n e . S u b s t i t u t i o n o f
a m e t h y l gro up i n a c e t i c a c i d t o y i e l d p r o p i o n i c a c i d l o w e r s t h e
i o n i z a t i o n c o n s t a n t by o n ly a f a c t o r o f 1 . 3 . I n g e n e r a l , s u b s t i t u t i o n
s h i f t s t h e n i t r o n i c a c i d c o n s t a n t s i n t h e d i r e c t i o n which would b e
p r e d i c t e d on t h e b a s i s of t h e i n d u c t i v e e f f e c t o f m e th y l g r o u p s a s
c o n t r a s t e d t o h y d r o g e n ( 4 2 ) .
S t e r i c e f f e c t s a r e p r o b a b l y u n i m p o r t a n t i n d i s s o c i a t i o n o f
n i t r o n i c a c i d s s i n c e , a p p a r e n t l y , t h e r e i s e s s e n t i a l l y no c h a n g e i n
g e o m e t r y o f t h e a n i o n r e l a t i v e t o i t s n i t r o n i c a c i d ( 4 5 ) .
(45) M. S. Nei-niian, " S t e r i c E f f e c t s i n O r g a n i c C h e m i s t r y " , J o h n W i ley and S o n s , I n c . , New York , 1 9 6 3 , p . 4 4 0 - 4 1 .
The e x i s t e n c e o f two i s o e l e c t r o n i c a c i - a n i o n s (A and B,
E q u a t i o n 11) has b e e n p o s t u l a t e d by T u r n b u l l and Maron (42) t o
e x p l a i n t h e o b s e r v e d o r d e r f o r t h e i o n i z a t i o n c o n s t a n t s of s i m p l e
n i t r o compounds ( 2 - n i t r o p r o p a n e > n i t r o e t h a n e > n i t r o m e t h a n e ) . T h i s
c o n c e p t was f i r s t p o s t u l a t e d by P e d e r s o n (10) an d J u n e l l ( 1 7 ) . I t
26
i s i n c o n f l i c t w i t h t h e p r o p o s a l o f Hammett (4 6 ) t h a t t h e a c i - a n i o n
(4 6 ) L. P. H am m et t , " P h y s i c a l O r g a n i c C h e m i s t r y " , McGraw- H i l l Book C o . , I n c . , Mew Y o r k , 1940 , p . 67 .
i s a r e s o n a n c e h y b r i d w i t h t h e n e g a t i v e c h a r g e s p r e a d o v e r t h e
c a r b o n , n i t r o g e n , a n d o x y g e n a toms ( p r i m a r i l y on t h e o x y g e n ) , and
w i t h mod ern r e s o n a n c e t h e o r y . R e c e n t l y a n i n v e s t i g a t i o n has b e e n
made o f t h e mechani sm o f t a u t o m e r i c t r a n s f o r m a t i o n s o f p h e n y l n i t r o -
m e t h a n e i n t h e r a n g e pH 1 - 1 0 u s i n g p o l a r o g r a p h y ( 4 7 , 4 8 ) . T h i s work
(4 7 ) V. M. B e l i k o v , S. G. M a i r a n o v s k i i , T s . B. Korchcm naya , S . S . N o v ik o v , and V. A. K l im o v a , B u l l . Acad. S c i . U . S . S . R . , D i v . Chem. S c i . , 1960, 1553 (E ng . T r a n s i . )
(48 ) I b i d . , 16 6 3 .
o n c e a g a i n opens t h e q u e s t i o n o f t h e e x i s t e n c e o f two d i s t i n c t
a n i o n s (p r e s u m a b l y o f d i f f e r e n t g e o m e t r y ) i n e q u i l i b r i u m w i t h e a c h
o t h e r a n d w i t h b o t h t h e n i t r o compound and i t s n i t r o n i c a c i d . As
e x p r e s s e d by T u r n b u l l a n d Maron (42) t h e f o l l o w i n g e q u i l i b r i a a r e
b e l i e v e d t o e x i s t :
R.CHNO. + H 0 r R.C-NO + H 0 — — R C = NO +2 2 2 ^ 2 2 3 ^ 2 2
A B
+. (
3H^O —----- ^ R C = NO H + H 0 (11)a t 9 9 9
27
I n t e r m s of t h e s e f o r m u l a t i o n s E q u a t i o n 11 may b e w r i t t e n f o r t h e
p r i m a r y d i s s o c i a t i o n c o n s t a n t f o r t h e n i t r o f o r m ,
k ' .[ N i t r o ] ( ^ 2 )
t h a t o f t h e a c i f o r m i s
[H]0*][B]
^ a c i " [N i t ro ]
a n d t h e e q u i l i b r i u m r a t i o o f B to A i s
K = [ B ] / [ A ] (1 4 )
T h e r e f o r e , K , a s d e f i n e d by E q u a t i o n 1 0 , bec omes N
f
K = K (K + 1) ( 1 5 )N i.'î
I
a n d becomes K = K . (K + 1 ) /K ( 1 6 )a c i a c i
F ro m t h i s , i t i s a p p a r e n t t h a t K and K , d e r i v e d from E q u a t i o n 10N a c i
a r e n o t t h e d i r e c t i o n i z a t i o n c o n s t a n t s , b u t a r e r e l a t e d t h r o u g h
t h e c o n s t a n t K. F u r t h e r , i t f o l l o w s f r o m t h i s f o r m u l a t i o n , t h a t
t h e b a s e c o n s t a n t s o f A and B a r e d i f f e r e n t , and t h a t i n any r e a c t i o n
i n v o l v i n g s a l t s o f a n i t r o compound, t h e b e h a v i o r a n t i c i p a t e d i s
t h a t o f two a n i o n s o f d i f f e r e n t b a s i c s t r e n g t h s .
T u r n b u l l an d M ar o n assume t h a t K i s l a r g e s i n c e n e g a t i v e
c h a r g e i s most l i k e l y t o r e s i d e on t h e e l e c t r o n e g a t i v e oxyg en a t o m s .
28
a n d b e c a u s e o f t h e sy m m et ry o f a n i o n B. I f K i s l a r g e , t h e n E q u a t i o n sI I
15 a n d 16 r e d u c e e s s e n t i a l l y t o K = (K K) a n d K = K I n t h eN N a c i a c i
l a t t e r , t h e e f f e c t o f s u b s t i t u t i o n of m e t h y l g r o u p s f o r h y d r o g e n
s h o u l d l e a d t o a more o r l e s s no rm al d e c r e a s e i n K . w i t h s u b s t i -a c i
t u t i o n , and such i s a c t u a l l y t h e c a s e a s h a s b e e n i l l u s t r a t e d a b o v e .
W i t h K , how ever , two i n d u c t i v e e f f e c t s o f s u b s t i t u t i o n must b e c o n - d I I
s i d e r e d , one on K, a nd o ne on K. As f a r a s K i s c o n c e r n e d , t h eN N ,
f i r m e r a t t a c h m e n t o f p r o t o n s t o t h e a l p h a - c a r b o n may be e x p e c t e d t oI
r e s u l t a g a i n i n a d e c r e a s e i n on p a s s i n g f r o m n i t r o m e t h a n e t o
n i t r o e t h a n e to 2 - n i t r o p r o p a n e . On th e o t h e r h a n d , t h e s t r o n g e r
a f f i n i t y f o r p r o t o n s r e s u l t i n g f rom r e p l a c e m e n t o f h y d r o g e n s w i t h
m e t h y l g r o u p s i s e q u i v a l e n t t o a d e c r e a s e i n e l e c t r o n a f f i n i t y o f
t h e c a r b o n , and h e n c e s u b s t i t u t i o n s h o u l d f a v o r form B ov e r A w i t h
a r e s u l t a n t i n c r e a s e i n K. As t h e i n c r e a s e i n K may w e l l o u t w e i g hI
t h e d e c r e a s e i n K^,, K may i n c r e a s e a p p r e c i a b l y w i t h s u b s t i t u t i o n , a N
w h i c h e x p l a i n s t h e o b s e r v e d d a t a . T h i s e x p l a n a t i o n i s t h o u g h t a l s o
t o a c c o u n t f o r t h e l a r g e i n c r e a s e i n t h e t a u t o m e r i c e q u i l i b r i u m
c o n s t a n t s , K , o b s e r v e d i n t h i s s e r i e s .T
Wheland and F a r r (A3) have n o t e d t h e e x p l a n a t i o n g i v e n by
T u r n b u l l and Maron an d h a v e r a i s e d s e r i o u s q u e s t i o n t o i t on t h e
b a s i s o f s t u d i e s of - th e a c i d i t i e s o f c a r b o x y l i c a c i d s and b e c a u s e
i t i s n o t o b v i o u s how s u c h an e x p l a n a t i o n w o u ld t r e a t 1 - n i t r o p r o p a n e .
They h a v e i n s t e a d e x p l a i n e d t h e o b s e r v e d s e q u e n c e o f a c i d s t r e n g t h s
29
o n t h e b a s e s o f e l e c t r o s t a t i c i n t e r a c t i o n (4 3 ) o r f i e l d e f f e c t s ( 4 9 ) .
( 49 ) H in e , p p . 6 0 - 6 3 .
I n t e r m s o f t h e t r e a t m e n t sum m ar ize d by H i n e , i t i s e x p e c t e d t h a t
s i n c e t h e p o s i t i v e end o f t h e c a r b o n - n i t r o d i p o l e i s n e a r e r t h e
a c i d i c p r o t o n , t h a n i s t h e n e g a t i v e e n d , t h e r e w i l l be a n e t
r e p u l s i o n o f t h e p r o t o n . F o r t h i s r e a s o n l e s s w ork w i l l be r e q u i r e d
t o re m ove i t t h a n i f t h e c a r b o n - n i t r o d i p o l e w e r e a b s e n t . The
d i f f e r e n c e i n t h e am o u n t s o f work r e q u i r e d d e p e n d s on t h e m a g n i t u d e
a n d o r i e n t a t i o n of t h e d i p o l e , i t s d i s t a n c e f r o m t h e a c i d i c p r o t o n ,
a n d t h e d i e l e c t r i c c o n s t a n t o f t h e medium t h r o u g h which t h e i n t e r
a c t i n g l i n e s of f o r c e m u s t p a s s . Thi s e x p l a n a t i o n us ed by Whe land
and F a r r t o r a t i o n a l i z e t h e a c i d i t i e s o f t h i s s e r i e s o f n i t r o
com pounds i s e s s e n t i a l l y t h e same as t h a t u s e d by Wes th e imer and
S h o o k h o f f (50) f o r t h e a c i d i o n i z a t i o n c o n s t a n t s o f s u b s t i t u t e d
m a l o n i c a c i d s .
(5 0 ) F . H. W e s t h e i m e r and M. W. S h o o k h o f f , J . Am. Chem, S o c . , 61 , 555 ( 1 9 3 9 ) .
B e l i k o v and c o - w o r k e r s (47) p r e f e r r e d t h e e x p l a n a t i o n o f
T u r n b u l l and Maron a p p a r e n t l y b e c a u s e t h e y f e e l t h a t t h e f i e l d
t h e o r y s h o u l d be a b l e t o e x p l a i n d i f f e r e n c e s i n a c i d i t i e s o f
compou nds i n o t h e r hom o lo g o u s s e r i e s su ch a s t h e 1 , 1 - d i n i t r o a l k a n e s .
30
H o w e v e r , t h e a d d i t i o n o f a m e t h y l g r o u p t o d i n i t r o m e t h a n e r e s u l t s i n
a d e c r e a s e i n s t e a d o f a n i n c r e a s e i n t h e a c i d d i s s o c i a t i o n c o n s t a n t
a s w o u l d h a v e b e e n p r e d i c t e d .
A n o t h e r e x p l a n a t i o n (51) s u g g e s t s t h e l o w e r a c i d i t y o f 1 , 1 -
( 5 1 ) H. E. S i t z m a n n , H. G. A d o l p h , a n d M. J . K a m l e t , i b i d . , 9 0 , 2815 (1 9 6 8 ) .
d i n i t r o e t h a n e t h a n d i n i t r o m e t h a n e i s due t o g r e a t e r 0 - 0 r e p u l s i o n s
a r i s i n g f r om s t e r i c f a c t o r s c a u s i n g t h e n i t r o g r o u p s i n t h e i o n t o
b e l e s s c o p l a n a r w i t h i n c r e a s e d s u b s t i t u t i o n .
T h i s o b s e r v e d t r e n d i n t h e r e l a t i v e a c i d i t i e s o f t h e s i m p l e
m o n o n i t r o compounds h a s a l s o b e e n e x p l a i n e d on t h e b a s i s o f h y p e r -
c o n j u g a t i v e s t a b i l i z a t i o n o f t h e n i t r o n a t e i o n (5 2 , 5 3 ) and r e l e a s e
(5 2 ) II. M. E. C a r d w e l l , i b i d . , 2442 ( 1 9 5 1 ) .
(5 3 ) C. K. I n g o l d , " S t r u c t u r e and M ec han i sm i n O r g a n i c C h e m i s t r y " , C o r n e l l U n i v e r s i t y P r e s s , New Y o r k , N .Y . , 1953, p p . 5 5 9 - 5 5 1 .
o f s t e r i c s t r a i n (45 ) on c o n v e r s i o n o f t h e n i t r o compounds t o t h e i r
a n i o n s .
Th e r a t e s o f i o n i z a t i o n and t h e a c i d d i s s o c i a t i o n c o n s t a n t s
o f s e v e r a l n i t r o a l k a n e s h a v e b e e n compar ed ( 5 4 , 5 5 ) . I n g e n e r a l , i t
(5 4 ) S. H. Maron an d V. K. La Mer , J . Am. Chem. S o c . , 6 1 , 20 1 8 ( 1 9 3 9 ) .
( 5 5 ) R. G. P e a r s o n an d R. L. D i l l o n , i b i d . , 7_5, 2439 ( 1 9 5 3 ) .
31
a p p e a r s t h a t n i t r o a l k a n e s o t h e r t h a n n i t r o m e t h a n e , n i t r o e t h a n e a n d
2 - n i t r o p r o p a n e a r e c o n s i d e r a b l y s t r o n g e r a c i d s t h a n t h e i r r a t e s o f
i o n i z a t i o n ( r e a c t i o n w i t h w a t e r ) i n d i c a t e . T h e r e f o r e , n i t r o a l k a n e s
d e v i a t e s i g n i f i c a n t l y i n a B r o n s t e d p l o t b e t w e e n t h e log o f t h e i r
a c i d i o n i z a t i o n c o n s t a n t s , and th e l o g o f t h e i r r a t e c o n s t a n t s
f o r i o n i z a t i o n i n w a t e r ( 5 3 ) .
T h i s d e v i a t i o n f r o m a l i n e a r f r e e e n e r g y r e l a t i o n s h i p c a n be
r a t i o n a l i z e d s i n c e t h e c h a r g e i n th e a n i o n i s d i s p e r s e d by r e s o n a n c e
i n t h e n i t r o g r o u p . I t i s s u g g e s t e d (56 ) t h a t a l i n e a r f r e e e n e r g y
(56) J . E. L e f f l e r , "The L le ac t iv e I n t e r m e d i a t e s of O r g a n i c C h e m i s t r y " , I n t e r s c i e n c e P u b l i s h e r s , I n c . , New York ( 1 9 5 6 ) .
r e l a t i o n s h i p ca n b e e x p e c t e d , though n o t d e r i v e d , whenever t h e
s t r u c t u r e o f t h e t r a n s i t i o n s t a t e f o r t h e n e u t r a l i z a t i o n o f a c a r b o n
a c i d a n d t h e s t r u c t u r e o f i t s a n io n r e s e m b l e o n e a n o t h e r . The
m ark e d d e v i a t i o n i n a B r o n s t e d p l o t f o r n i t r o compounds (55) i n d i c a t e s
t h a t t h e s t r u c t u r e o f t h e a n i o n and t h e t r a n s i t i o n s t a t e a r e m a r k e d l y
d i f f e r e n t d u e , p o s s i b l y , t o t h e r e l a t i v e u n i m p o r t a n c e of r e s o n a n c e
( d e l o c a l i z a t i o n ) i n t h e t r a n s i t i o n s t a t e f o r t h e f o r m a t i o n o f t h e
e n o l a t e _
0
B H C NI \R. 0
S i m i l a r l y , I n g o l d (53) h a s p r o p o s e d t h a t t h e C-N d o u b l e bond
i s n o t a p p r e c i a b l y fo rm e d i n t h e t r a n s i t i o n s t a t e d u r i n g t h e
n e u t r a l i z a t i o n p r o c e s s . T h i s w o u ld , t h e r e f o r e , i n d i c a t e t h a t t h e
same f a c t o r s w h ic h s t a b i l i z e t h e a n i o n a r e n o t s i g n i f i c a n t i n
s t a b i l i z a t i o n o f t h e t r a n s i t i o n s t a t e . S i n c e t l ie t r a n s i t i o n s t a t e
f o r n e u t r a l i z a t i o n i s n o t h i g h l y d e l o c a l i z e d t h r o u g h t h e n i t r o
g r o u p , t h e o b s e r v e d o r d e r : n i t r o m e t h a n e > n i t r o e t h a n e > 2 - n i t r o
p r o p a n e i s u n d e r s t a n d a b l e f o r t h e r a t e s o f i o n i z a t i o n .
W i l l i a m s (5 7 ) h a s e x t e n d e d t h e s u g g e s t i o n o f Hammond (45)
(57) F . F . W i l l i a m s , Ph.D. d i s s e r t a t i o n , The Ohio S t a t e U n i v e r s i t y , 1958 .
t h a t t h e i o n i z a t i o n c o n s t a n t s o f s i m p l e n i t r o a l k a n e s ca n be
e x p l a i n e d on t h e b a s i s o f s t e r i c f a c t o r s . W i l l i a m s t h u s p o s t u l a t e s
t h a t t h e r a t e s o f i o n i z a t i o n o f t h e s e compounds m ig h t be e x p l a i n e d
by e m p h a s i z in g t h e i m p o r t a n c e o f s t e r i c s t r a i n s i n c e i f , i n t h e
t r a n s i t i o n s t a t e , t h e C-W d o u b l e bond i s n o t a p p r e c i a b l y fo rmed and
t h e C-H bond i s h i g h l y b r o k e n , t h e u n c h a r g e d p a i r o f e l e c t r o n s m i g h t
o cc upy an a t o m i c o r b i t a l o f n e a r l y p u r e s - c h a r a c t e r w h ich w o u l d , i n
t u r n , mean t h e R-C-R b o n d a n g l e s would b e a p p r o x i m a t e l y 9 0 ° . T h u s ,
i n c o n v e r s i o n o f t h e g r o u n d s t a t e t o t h e t r a n s i t i o n s t a t e , t h e r e
i s an a n g l e ch a n g e f rom t h e n o rm a l t e t r a h e d r a l a n g l e t o a 90° a n g l e
r e s u l t i n g i n g r e a t e r c o m p r e s s i o n o f t h e R g r o u p s i n t h e t r a n s i t i o n
s t a t e . T h i s c o m p r e s s i o n s h o u l d r a i s e t h e t r a n s i t i o n s t a t e e n e r g y
i n p r o p o r t i o n t o t h e s i z e o f t h e R g r o u p s .
33
A n i t r o compound c o n t a i n i n g an e l e c t r o n - w i t h d r a w i n g s u b
s t i t u e n t on i t s a l p h a - p o s i t i o n n e u t r a l i s e s more r a p i d l y and i s
s t r o n g e r t h a n i t s u n s u b s t i t u t e d p a r e n t . The i n c r e a s e i n a c i d
s t r e n g t h i s due e n t i r e l y t o t h e i n c r e a s e d r a t e o f i o n i z a t i o n s i n c e
t h e r a t e o f r e c o m b i n a t i o n o f t h e p r o t o n w i t h t h e e l e c t r o n e g a t i v e l y
s u b s t i t u t e d i o n i s a l s o i n c r e a s e d ( 5 5 ) .
F o r r a t e s o f i o n i z a t i o n o f compounds o f t h e ty p e
Î 'X - C - G
H
w h e r e G i s a s t r o n g e l e c t r o n - w i t h d r a w i n g s u b s t i t u e n t ( e . g . , n i t r o
o r cy a n o ) and an d a r e o t h e r s u b s t i t u e n t s ( e . g . , a l k y l o r
h a l o g e n ) , T a f t (58) fo u n d a c o r r e l a t i o n b e t w e e n s igma and t h e
(5 8 ) R. W. T a f t , J r . , J . Am. Chem. S o c . , 1J_, 5075 ( 1 9 5 7 ) .
l o g o f t h e r a t e c o n s t a n t f o r i o n i z a t i o n . Sigma i s t h e r e s o n a n c e
p a r a m e t e r which m e a s u r e s t h e power o f a s u b s t i t u e n t group t o
d e l o c a l i z e n e g a t i v e c h a r g e by c o n j u g a t i o n . T h i s c o r r e l a t i o n d o e s
n o t c o n s i d e r t h e a b i l i t i e s o f t h e s u b s t i t u e n t s , X, t o d i s p e r s e
e l e c t r o n i c c h a r g e by c o n j u g a t i o n b u t d o e s i n c l u d e t h e i r a b i l i t i e s
t o r e l e a s e o r a c c e p t e l e c t r o n s by i n d u c t i o n .
Fukuyama (2 5 ) d e t e r m i n e d s e c o n d - o r d e r r a t e c o n s t a n t s , k i n e t i c
p a r a m e t e r s and d i s s o c i a t i o n c o n s t a n t s o f m e t a - a n d p a r a - s u b s t i t u t e d
34
1—p h e n y I n i t r o e t h a n e s i n 50% by volume 1 , 4 - d i o x a n e - w a t e r . The d a t a
g i v e s a t i s f a c t o r y Hammett c o r r e l a t i o n o f r a t e s o f n e u t r a l i z a t i o n o f
t h e 1 - p h e n y l n i t r o e t h a n e s w i t h s igma v a l u e s f o r b e n z o i c a c i d s i n
w a t e r ( l o g v e r s u s s i g m a ) . The r h o v a l u e s f o r n e u t r a l i z a t i o n a t
0 , 10 and 20° a r e 1 . 9 0 7 , 1 . 8 9 and 1 . 9 0 r e s p e c t i v e l y . An im p r o v e d
l i n e a r c o r r e l a t i o n ( r h o = 1 . 3 ) was o b t a i n e d b e t w e e n t h e r a t e s o f
n e u t r a l i z a t i o n o f t h e 1 - p h e n y l n i t r o e t h a n e s a t 0° and t h e s ig m a
v a l u e s d e r i v e d f r o m i o n i z a t i o n c o n s t a n t s f o r s u b s t i t u t e d b e n z o i c i n
50% by volume 1 , 4 - d i o x a n e - w a t e r ( 2 5 ) . The i o n i z a t i o n c o n s t a n t s o f
t h e s u b s t i t u t e d 1 - p h e n y l n i t r o e t h a n e s g i v e a good Hamne t t c o r r e l a t i o n
w i t h s i g n a s u b s t i t u e n t v a l u e s ( rh o = 1 . 7 ) . Of g r e a t e s t s i g n i f i c a n c e
t o t h e o b j e c t i v e s o f t h e p r e s e n t s t u d y i s t h a t t h e r e i s e x c e l l e n t
B r o n s t e d c o r r e l a t i o n o f t h e l o g a r i t h m o f t h e n e u t r a l i z a t i o n r a t e
c o n s t a n t s and t h e i o n i z a t i o n c o n s t a n t s f o r s u b s t i t u t e d 1 - p h e n y l
n i t r o e t h a n e s . The r e s u l t s o b t a i n e d t h u s d i f f e r f r om t h o s e o b t a i n e d
w i t h l o w e r a l i p h a t i c n i t r o compounds . The c o r r e l a t i o n w i t h t h e
1 - p h e n y l n i t r o e t h a n e s a p p a r e n t l y i s o b t a i n e d b e c a u s e t h e s y s t e m i s
n o t c o m p l i c a t e d b y s t e r i c d i f f e r e n c e s ( 2 5 ) .
R e c e n t l y ( 5 9 ) , t h e u l t r a v i o l e t s p e c t r a o f n i t r o n a t e a n i o n s
(59 ) F . F . W i l l i a m s , P . W. K. F l a n a g a n , W. J . T a y l o r , H. S h e c h t e r , J . Org. Chem . , 2674 ( 1 9 6 5 ) .
h a v e bee n c o r r e l a t e d b y s i m p l e m o l e c u l a r o r b i t a l m e t h o d s . The
35
p o l a r i t y c a l c u l a t e d f o r t h e c a r b o n i t r o n a t e i s i n a g r e e m e n t w i t h t h a t
s u g g e s t e d by P e a r s o n and D i l l o n ( 5 3 ) . The low e l e c t r o n d e n s i t y
a s sum ed f o r c a r b o n p e r m i t s g r e a t e r i n d u c t i v e s t a b i l i z a t i o n o f t h e
c a r b o n i t r o n a t e a s m e t h y l i s s u b s c i t u t e d f o r h y d ro g e n and e x p l a i n s
t h e o b s e r v e d i o n i z a t i o n c o n s t a n t s , 2 - n i t r o p r o p a n e n i t r o e t h a n e
n i t r o m e t h a n e .
K a m le t (60 ) h a s s t u d i e d t h e i o n i z a t i o n c o n s t a n t s o f 1 - 1 - d i -
(6 0) See r e f e r e n c e (51) and r e f e r e n c e s t h e r e i n .
n i t r o a l k a n e s and t h e c o n f o r m a t i o n o f t h e i r a n i o n s . As e x p e c t e d ,
t h e i o n i z a t i o n c o n s t a n t s o f t h e s e m o l e c u l e s a r e g r e a t e r t h a n t h e
a c i d i t i e s o f t i i e i r m o n o - f u n c t i o n a l a n a l o g s . The pK 's o f an e x t e n s i v e
s e r i e s o f d e r i v a t i v e s o f 1 , 1 - d i n i t r o m e t h a n e h a v e been c o r r e l a t e d by
R u s s i a n w o r k e r s ( 6 1 ) . T h i s c o r r e l a t i o n b e t w e e n t h e pK’ s f o r 1 , 1 -
(61 ) V. I . S l o v e t s k i i , S. A. S h e v e l e v , V. I , B r a s h k o , L, I . B i r y u k o v a , A. A. F a i n z i l ’b e r g , and S. S . N oviko v, I z v . Akad, Nauk SSSR, S e r . K h i m . , 655 ( 1 9 6 6 ) .
d i n i t r o a l k a n e s a n d t h e T a f t p o l a r s u b s t i t u e n t c o n s t a n t , s i g n a - s t a r ,
h a s b e e n m o d i f i e d by K a m le t . D e v i a t i o n s f r o m t h e p r e d i c t e d l i n e a r
r e l a t i o n s h i p h a v e b e e n e x p l a i n e d on t h e b a s i s o f s t e r i c f a c t o r s .
T h e s e w o r k e r s and p r e v i o u s w o r k e r s i n t h i s l a b o r a t o r y (62) h a v e
(62 ) p K ' s o f 1 , 1 - d i n i t r o a l k a n e s h a v e b e e n m eas u r ed by D r s . D. B r a i n , R. K a p la n and T, M o r i t s u g u .
36
found t h a t t h e p K ' s o f 1 , 1 - d i n i t r o a l k a n e s a r e e x t r e m e l y s e n s i t i v e t o
s t e r i c e f f e c t s a t t h e 2 - p o s i t i o n .
T h i s e x p l a n a t i o n would a c c o u n t f o r t h e " s a t u r a t i o n e f f e c t "
n o t e d by P e a r s o n and D i l l o n ( 5 5 ) . They f o u n d t h a t a l t h o u g h t h e
fo r w a r d r a t e o f n e u t r a l i z a t i o n o f t h e d i n i t r o m e t h a n e i s v e r y much
f a s t e r t h a n t h a t f o r n i t r o m e t h a n e , t h e r a t e c o n s t a n t f o r t h e
r e c o m b i n a t i o n s t e p was a l s o s l i g h t l y f a s t e r f o r d i n i t r o m e t h a n e a n i o n
t h a n f o r n i t r o m e t h a n e a n i o n . T h i s was e x p l a i n e d on t h e b a s i s t h a t
th e s e c o n d n i t r o g r o u p i n c r e a s e s the e l e c t r o n e g a t i v i t y o f t h e c e n t r a l
c a r b o n a tom to t h e p o i n t w he re i t c o n t r o l s a g r e a t e r s h a r e o f t h e
n e g a t i v e c h a r g e t h a n i t d i d i n t h e m o n o - n i t r o d e r i v a t i v e .
F a c t o r s A f f e c t i n g R e a c t i v i t i e s o f C y c l i c Systems
I - S t r a i n T h e o r y . — The manner i n w h i c h r e a c t i v i t y a t a r i n g
s i t e v a r i e s w i t h r i n g s i z e i s o f pr ime c o n c e r n i n t h e p r e s e n t i n v e s t i
g a t i o n . I t h a s b e e n p r o p o s e d ( 6 3 , 6 4 , 6 5 ) t h a t r e a c t i v i t i e s o f v a r i o u s
(63) H. C. Brotvn, R. S. F l e t c h e r a n d R. B. J o h a n n e s e n , J .Am. Chem. S o c . , 2 2» 212 ( 1 9 5 1 ) .
(64) H. C. Brown and M. Bork ow sk i , i b i d . , 7 4 , 1894 ( 1 9 5 2 ) .
(65) P . D. B a r t l e t t , B u l l . s o c . C h i m . , ClOO (1 9 5 1 ) .
c y c l i c s y s t e m s c a n be c o r r e l a t e d w i t h t h e c h a n g e , r e l a t i v e t o t h e
g roun d s t a t e , i n i n t e r n a l s t r a i n ( I - s t r a i n ) w h i c h ac c o m p a n ie s t h e
f o r m a t i o n o r b r e a k i n g o f a bond to a r i n g a to m i n t h e r a t e d e t e r m i n i n g
37
s t e p o f a r e a c t i o n . R e a c t i o n s i n v o l v i n g a n i n c r e a s e i n t h e s e i n t e r n a l
s t r a i n s th us w i l l b e h i n d e r e d w h e r e a s t h o s e p r o c e e d i n g w i t h a d e c r e a s e
i n i n t e r n a l s t r a i n s w i l l b e a s s i s t e d ( 6 3 ) .
At t h i s t i m e , t h r e e p r i n c i p a l s o u r c e s o f s t r a i n i n c y c l i c
s y s t e m s a r e r e c o g n i z e d ( 6 6 ) : (1) c o m p r e s s i o n o f van d e r Waals r a d i i ,
(66) H. C. Brown and G, Ham, J . Am. Chem. S o c . , 78^, 2735( 1 9 5 6 ) .
(2 ) d i s t o r t i o n o f b o n d a n g l e s , and (3) bond o p p o s i t i o n f o r c e s . I n
s m a l l r i n g s ( 3 - , a n d 4 - m e m b e r e d ) , d i s t o r t i o n o f bond a n g l e s a p p e a r s
t o be t h e m a j o r s o u r c e o f s t r a i n ( 6 3 , 6 4 ) . I n common s i z e r i n g s ( 5 - ,
6 - and 7- r aembered ) , b o n d o p p o s i t i o n f o r c e s a r e p r i m a r i l y r e s p o n s i b l e
f o r i n t e r n a l s t r a i n ( 6 7 , 6 8 ) , w h e re a s i n medium s i z e r i n g s ( 8 - t h r o u g h
(67) K. S. P i t z e r , S c i e n c e , 1 0 1 , 672 ( 1 9 4 5 ) .
(68) J . E. K i l p a t r i c k , K. S. P i t z e r and R. S p i t z e r , J . Am.Chem. S o c . , 2483 ( 1 9 4 7 ) .
1 2 -m e m b e re d ) , bond o p p o s i t i o n s and c o m p r e s s i o n o f v an d e r Waal s
r a d i i a r e i n v o l v e d ( 6 9 ) .
(69) V. P r e l o g , J . Chem. S o c . , 420 ( 1 9 5 0 ) .
I d e a l l y , t h e e f f e c t o f r e a c t i o n a t a s i t e on a r i n g s h o u l d
b e a n a l y z e d i n t e r m s o f e a c h of t h e s e s t r a i n f a c t o r s . However ,
38
t h e s t r a i n f a c t o r s a r e n o t m u t u a l l y i n d e p e n d e n t and t h e y c a n n o t be
e s t i m a t e d s e p a r a t e l y w i t h a c c u r a c y a t t h i s t i m e . On t h e o t h e r h a n d ,
t h e n e t change i n i n t e r n a l s t r a i n a c c o m p a n y i n g t h e m ak ing o r b r e a k i n g
o f a bond to a r i n g a tom ca n be e s t i m a t e d w i t h c o n s i d e r a b l e p r e c i s i o n
f r o m r a t e , e q u i l i b r i u m a n d t h e r m o c h e m i c a l d a t a . T h e r e f o r e , i t seems
d e s i r a b l e to d i s c u s s t h e e f f e c t o f r i n g s i z e on r a t e s o f r e a c t i o n s
i n t e r m s of t h e n e t c h a n g e i n i n t e r n a l - s t r a i n w h ic h a c c o m p a n i e s t h e
r e a c t i o n . I t s h o u l d b e r e c o g n i z e d t h a t I - s t r a i n w i l l be made up o f
i n d i v i d u a l c o n t r i b u t i o n s f rom a n g l e d e f o r m a t i o n s , bond o p p o s i t i o n s ,
a n d a t o m i c c o m p r e s s i o n s , t h e r e l a t i v e m ag n i tu d e 's o f w h ic h w i l l v a r y
f r o m s y s t e m to s y s t e m ( 6 6 ) . I t s h o u l d a l s o b e r e c o g n i z e d t h a t
I - s t r a i n e f f e c t s w i l l n o t be t h e o n l y f a c t o r i n f l u e n c i n g c h e m i c a l
b e h a v i o r o f c y c l i c com pounds . I t i s c l a i m e d , h o w e v e r , t h a t i n t e r n a l
s t r a i n i s i m p o r t a n t and i n s i m p l e s y s t e m s i s d o m i n a n t ( 7 0 ) .
(70) H. C. Brown and K. I c h i k a w a , T e t r a h e d r o n , 3 , 221 ( 1 9 5 7 ) .
On t h i s b a s i s , r e a c t i o n s i n w h i c h a r i n g a tom u n d e r g o e s a
c h a n g e f rom t e t r a h e d r a l t o t r i g o n a l b o n d i n g s h o u l d be s t r o n g l y
h i n d e r e d i n c y c l o p r o p a n e s and c y c l o b u t a n e s due t o s t r a i n i n c r e a s e
ac co m p an y in g t h e i n c r e a s e d bond a n g l e d i s t o r t i o n s ( 6 6 ) . C o n v e r s e l y ,
r e a c t i o n s i n v o l v i n g a c h a n g e o f t r i g o n a l t o t e t r a g o n a l b o n d i n g
s h o u l d be s t r o n g l y f a v o r e d i n 3- and 4-membered r i n g compo un ds .
39
A n g l e s t r a i n e f f e c t s a r e e x p e c t e d t o be r e l a t i v e l y u n i m p o r t a n t i n
l a r g e r r i n g compounds s i n c e t h e y a r e c a p a b l e o f a d j u s t i n g w i t h
r e l a t i v e e a s e t o t h e g e o m e t r i c a l r e q u i r e m e n t s o f a t e t r a h e d r a l o r a
t r i g o n a l a t om . A c h a n g e i n s t r u c t u r e o f a r i n g a tom from t e t r a
h e d r a l t o t r i g o n a l s h o u l d r e d u c e bond o p p o s i t i o n s i n c y c l o p e n t a n e s ,
c y c l o h e p t a n c s an d i n m e d i u m - s i z e d r i n g s and i n c r e a s e t h e s e f o r c e s
i n c y c l o ’n e x a n e s . I t a l s o i s e x p e c t e d t h a t t r i g o n a l b o n d i n g w i l l
r e d u c e c o m p r e s s i o n o f v a n d e r Waals r a d i i i n r a e d i u m - s i z e r i n g s .
From t h e s e c o n s i d e r a t i o n s , t h e f o l l o w i n g r e l a t i v e r e a c t i v i t i e s
h a v e b e e n p r e d i c t e d f o r r e a c t i o n s o f a g i v e n t y p e :
R e l a t i v e O r d e r Type o f R e a c t i o n o f R e a c t i v i t y
s p ^ ---------- > s p ^ 8 > 5 > 7 > 6 > 4 > 3
s p ^ ---------- > s p^ 3 > 4 > 6 > 7 > 5 > 8
The e x p e c t e d o r d e r s f o r 3 - , 5 - , 6 - , 7 - and 8-meinbered r i n g s
h a v e b e e n o b s e r v e d i n c e r t a i n s e r i e s . C y c l o b u t a n e d e r i v a t i v e s ,
h o w e v e r , o f t e n b e h a v e e r r a t i c a l l y . F o r e x a m p l e , 1 - c h l o r o - l - m e t h y l -
c y c l o b u t a n e s o l v o l y z e s (S 1) s l o w l y , a s e x p e c t e d ( 6 4 ) , b u t c y c l o -N
b u t y l c h l o r i d e and c y c l o b u t y l t o s y l a t e s o l v o l y z e ( S ^ l ) much more
r a p i d l y t h a n a n t i c i p a t e d ( 7 1 ) . C y c l o b u t y l c h l o r i d e and c y c l o b u t y l
(71) J . D. R o b e r t s and V. C. C ham bers , J . Am. Chem. S o c . , 7 3 , 5034 ( 1 9 5 1 ) .
40
t o s y l a t e s o l v o l y z e t o r e a r r a n g e d p r o d u c t s and t h e d r i v i n g f o r c e
a s s o c i a t e d w i t h r e a r r a n g e m e n t h a s b e e n p o s t u l a t e d t o a c c o u n t f o r
t h e e n h a n c e d r e a c t i v i t y ( 6 5 , 7 0 ) . h o w e v e r , c y c l o p r o p y l d e r i v a t i v e s
r e a r r a n g e t o t h e v e r y s t a b l e a l l y l c a t i o n , and t h e r e i s no a p p a r e n t
a c c e l e r a t i v e e f f e c t on t h e r a t e o f r e a c t i o n ( 7 1 ) .
T a b l e 9 s u m m a r i z e s some o f t h e s t u d i e s on t h e e f f e c t s o f r i n g
s i z e on t h e r e l a t i v e r e a c t i v i t i e s o f hom ologous c y c l i c compounds .
Two R e a c t i o n S e r i e s C o r r e l a t e d by I - S t r a i n T h e o r y . — Brown
( 6 6 , 7 0 ) h a s i n v e s t i g a t e d two f u n d a m e n t a l l y d i f f e r e n t r e a c t i o n s e r i e s
w h i c h a r e c o r r e l a t e d w i t h I - s t r a i n t h e o r y . The a c e t o l y s i s o f c y c l o -
a l k y l s u l f o n a t e s (66 ) p r o c e e d s w i t h t h e r e l a t i v e o r d e r : 8 » 7 > 5 >
4 > 6 . I n t h i s r e a c t i o n , t h e t r a n s i t i o n s t a t e i n t h e r a t e d e t e r
m i n i n g s t e p i n v o l v e s i o n i z a t i o n o f t h e s u l f o n a t e s and s h o u l d h a v e
2c o n s i d e r a b l e c a r b o n i u m i o n o r sp c h a r a c t e r . F o r t h i s r e a s o n ,
i o n i z a t i o n o f t h e 4-membered r i n g s u l f o n a t e s h o u l d p r o c e e d s l o w l y
and i s o b s e r v e d t o do so i n t h i s s e q u e n c e . A c c o r d i n g to t h e I - s t r a i n
i n t e r p r e t a t i o n , i o n i z a t i o n s h o u l d be f a v o r e d i n t h e 5 - and 7 - m e n b e r e d
r i n g s y s t e m s s i n c e t o r s i o n a l s t r a i n i s r e l i e v e d . I n a 6-membered
r i n g , h o w e v e r , t h e t r a n s i t i o n s t a t e w i l l h a v e a s e m i - e c l i p s e d c o n
f o r m a t i o n r e l a t i v e t o a g r o u n d s t a t e i n w h ic h t h i s s t r a i n i s a b s e n t .
R e d u c t i o n o f bond o p p o s i t i o n f o r c e s w i l l o c c u r i n t h e s t r a i n e d ( 6 8 ) ,
m e d i u m - s i z e r i n g s t h r o u g h r e d u c t i o n o f t h e bond nu mber .
41
TABLE 9
THE EFFECTS OF RING SIZE ON THE RELATIVE REACTIVITIES OF HOMOLOGOUS CYCLIC COMPOUNDS
C y c l i c S o l v o l y s i s o f C h l o r i d e s , S o l v o l y s i s o f T o s y l a t e s ,S y s te m 50% A q u e o u s E t h a n o l , 95° A c e t i c A c i d , 70°
(71 ) (66)
C y c l o p r o p y l a p p r o x . 0 a p p r o x . 0C y c l o b u t y l 41 1 1 . 3C y c l o p e n t y l 15 1 3 . 6C y c l o h e x y l 1 . 0 1 . 0C y c l o h e p t y l 2 5 . 3C y c l o o c t y l 191
S o l v o l y s i s o f 1 - C h l o r o - S o l v o l y s i s o fC y c l i c 1 - r a e t h y l D e r i v a t i v e s , K e t a l s , 50% D i -S y s te m 80% A que ous E t h a n o l , 25° o x a n e - W a t e r , 25°
(6 4 ) (80)
C y c l o p r o p y lC y c l o b u t y l 0 . 2 1 1 0 . 1 4C y c l o p e n t y l 124 • 3 . 4C y c l o h e x y l 1 . 0 0 1 . 0C y c l o h e p t y l 108 3 . 1C y c l o o c t y l 286 4 . 4
C y c l i c R e a c t i o n o f Bromides C y a n o h y d r i nS y s t e m w i t h K I , A c e t o n e , 90° D i s s o c i a t i o n C o n s t a n t s
96% E t h a n o l , 2 2 - 2 3 °(71 ) ( 7 2 ) (73 )
C y c l o p r o p y l no r e a c t i o nC y c l o b u t y l 1 . 4 16C y c l o p e n t y l 2 1 . 0 50C y c l o h e x y l 1 . 0 1 . 0 0 1 . 0C y c l o h e p t y l 130 150C y c l o o c t y l 860
42
TABLE 9 ( c o n t i n u e d )
THE RELATIVE REACTIVITIES OF HOMOLOGOUS CYCLIC COMPOUNDS
B o r o h y d r i d e N e u t r a l i z a t i o n o f C y c l i c N i t r o ComS i z e o f R e d u c t i o n o f p o u n d s by H yd ro x id e I o n i n
R i n g Sys tem C y c l i c K e t o n e s , 0° 50% U io x a n e - V J a t e r , 0°( 1 0 ) ( 1 8 ) (24) ( 1 9 )
3 0 . 0 0 . 0 04 1 . 6 4 32, 2 7 . 1 2 1 . 65 0 . 0 4 3 6 1 . 1 6 . 1 4 5 . 2 26 1 . 0 0 1 . 0 1 .0 0 1 . 0 07 0 . 0 0 6 3 4 4 . 1 3 .0 2 2 . 7 08 0 . 0 0 0 4 8 5 2 .3 0 2 . 1 0
43
C o n v e r s e l y , t h e t r e n d i s r e v e r s e d when a t r i g o n a l a to m i s c o n
v e r t e d t o a t e t r a h e d r a l a tom i n t h e t r a n s i t i o n s t a t e o f a r e a c t i o n o f
t h i s s e r i e s . T h u s , t h e r e l a t i v e r e a c t i v i t y o r d e r f o r r e d u c t i o n o f
4 - t h r o u g h 8-membered c y c l i c k e t o n e s by s o d i u m b o r o h y d r i d e i s 4 > 6 >>
5 > 7 > > 8 . To e x p l a i n t h e r e a c t i v i t y o f t h e 4-membered r i n g k e t o n e ,
i t was s u r m i s e d t h a t b o n d o p p o s i t i o n s a r e r e l a t i v e l y s m a l l and may be
n e g l i g i b l e i n t h e t r a n s i t i o n s t a t e . The m o s t i m p o r t a n t f a c t o r i s t h e
r e l i e f o f s t r a i n due t o a n g l e d e f o r m a t i o n s i n c o n v e r s i o n o f t h e
t r i g o n a l r i n g a to m t o t e t r a g o n a l . T h i s a r g u m e n t a l s o a s su m es a h i g h
d e g r e e o f r e h y b r i d i z a t i o n i n t h e t r a n s i t i o n s t a t e o f t h e r e a c t i n g
k e t o n e .
A p p a r e n t l y , o t h e r f a c t o r s a r e o p e r a t i v e s i n c e t h e r e l a t i v e
o r d e r s o f t h e 4 - a n d 6 -m em bered s y s t e m s a r e i n v e r t e d d e p e n d i n g on t h e
r e a c t i o n . A l s o , t h e m a g n i t u d e o f t h e d i f f e r e n c e s b e tw een s u c c e s s i v e
members seems to d e p e n d upon t h e r e a c t i o n b e i n g s t u d i e d .
Of i n t e r e s t i s t h e a p p a r e n t l i n e a r f r e e en e rg y r e l a t i o n s h i p
b e t w e e n t h e r a t e s o f t h e s o l v o l y s i s o r r e d u c t i o n r e a c t i o n s and t h e
c y a n o h y d r i n d i s s o c i a t i o n c o n s t a n t s f o r h o m o lo g o u s c y c l o a l k a n o n e s .
F o r t h e c y a n o h y d r i n s , t h e d i s s o c i a t i o n c o n s t a n t s v a ry a c c o r d i n g l y ;
8 > 7 > 5 > 4 > 6 ( 7 2 , 7 3 ) . The u n u s u a l l y h i g h d i s s o c i a t i o n c o n s t a n t
(7 2) V. P r e l o g an d M. K o b e l t , H e l v . c h i m . A c ta , _32_» H 8 7( 1 9 4 9 ) .
(73) 0 . H. W h e e l e r and E. G. de R o d r i g u e z , J . Org. Chera . ,2 9 , 718 ( 1 9 6 4 ) .
44
f o r c y c l o b u t a n e c y a n o h y d r i n r e l a t i v e t o t h e 6-membered r i n g i s
e x p l a i n e d (7 3 ) on t h e b a s i s o f t h e r e l a t i v e l y u n f a v o r a b l e i n t e r
a c t i o n s b e t w e e n t h e h y d r o x y l and cyano g r o u p s and r i n g h y d r o g e n a toms
i n t h e 4-m embered r i n g c y a n o h y d r i n .
O t h e r R e a c t i o n S e r i e s C o r r e l a t e d by I - S t r a i n T h e o r y . — A number
o f i n v e s t i g a t i o n s i n t h i s l a b o r a t o r y h a v e i n v o l v e d d e t e r m i n a t i o n o f
t h e e f f e c t s o f r i n g s i z e on t h e r e a c t i v i t y o f c y c l i c m o l e c u l e s u n d e r
g o i n g r e a c t i o n a t a r i n g p o s i t i o n ( 1 8 , 1 9 , 2 4 , 7 4 , 7 5 , 7 6 ) .
(7 4 ) C, A. M a t u s z a k , Ph .D. d i s s e r t a t i o n . The Ohio S t a t e U n i v e r s i t y , 1957 .
(7 5 ) T. J . D o u g h e r t y , i b i d . , 1959.
(76) J . J . K ane , i b i d . , 1960.
N i t r o c y c l o a l k a n e s w e re found to b e n e u t r a l i z e d by h y d r o x i d e
i o n a c c o r d i n g t o t h e s e q u e n c e 4 > > 5 > 7 > 8 > 6 > > 3 ( 1 8 , 1 9 , 2 4 ) .
W i t h t h e e x c e p t i o n o f n i t r o c y c l o b u t a n e , t h i s i s i n a c c o r d w i t h p r e s e n t
t h e o r i e s o f r e a c t i v i t y o f r i n g compounds . N i t r o c y c l o h e p t a n e an d
e s p e c i a l l y n i t r o c y c l o p e n t a n e a r e e x p e c t e d t o r e a c t f a s t e r t h a n n i t r o -
2c y c l o h e x a n e i f t h e t r a n s i t i o n s t a t e a c q u i r e s some sp c h a r a c t e r t h u s
l e a d i n g t o a d e c r e a s e i n bon d o p p o s i t i o n i n t h e 5 - and 7-m embered
r i n g compounds and an i n c r e a s e i n su ch f o r c e s i n t h e 6-membered r i n g
d e r i v a t i v e ( 7 7 ) . The i n c r e a s e i n s t r a i n a r i s i n g f rom i n c r e a s e d bon d
(77) H. C. Brown, J . H. B r e w s t e r , and H. S h e c h t e r , J . Am. Chem. S o c . , 76 , 467 ( 1 9 5 4 ) .
45
a n g l e d e f o r m a t i o n s h o u l d make c o n v e r s i o n o f n i t r o c y c l o p r o p a n e i n t o
i t s d e l o c a l i z e d a n i o n v e r y d i f f i c u l t .
C o n v i n c i n g e v i d e n c e h a s b e e n p r e s e n t e d (69) t h a t t h e medium
s i z e d r i n g s a r e s t r a i n e d . The s t r a i n i s p r e s u m a b l y t h e e f f e c t o f
b o n d o p p o s i t i o n f o r c e s , w i t h some c o n t r i b u t i o n f rom a t o m i c c o m p r e s s i o n .
H e r e a l s o , t h e i n t e r n a l s t r a i n s h o u l d b e p a r t i a l l y r e l i e v e d by a
d e c r e a s e i n t h e num ber o f b o n d s .
The h i g h r e a c t i v i t y o f n i t r o c y c l o b u t a n e i s n o t e x p e c t e d on
t h e b a s i s o f I - s t r a i n . T h i s o b s e r v a t i o n h a s b e e n e x p l a i n e d (19 ) by
two m o d i f i c a t i o n s o f t h e s t r a i n t h e o r y : (1 ) s o l v a t i o n o f t h e
t r a n s i t i o n s t a t e i s much more i m p o r t a n t i n s m a l l , r i g i d r i n g s t h u s
l o w e r i n g t h e a c t i v a t i o n e n t h a l p y f o r t h e c y c l o b u t y l s y s t e m r e l a t i v e
t o a n u n s o l v a t e d t r a n s i t i o n s t a t e , and (2 ) b o n d o p p o s i t i o n i s more
i m p o r t a n t i n c y c l o b u t y l d e r i v a t i v e s t h a n h a s b e e n p r e v i o u s l y p r o p o s e d .
5 - l I y d r o x y p e n t a n o i c a c i d l a c t o n e , a 6-mem bered l a c t o n e ,
h y d r o l y z e s i n t h e p r e s e n c e o f a c i d s o r b a s e s , more r a p i d l y t h a n an y
o f t h e 4 - t h r o u g h 8 -m em bered l a c t o n e s ( 7 3 ) . T h i s i s e x p l a i n e d on
t h e b a s i s o f r e l i e f o f s t r a i n f rom n o n - b o n d e d i n t e r a c t i o n s i n a
t r a n s i t i o n s t a t e w i t h a h i g h d e g r e e o f t e t r a g o n a l c h a r a c t e r . The
s l o w r a t e f o r 4 - h y d r o x y b u t a n o i c a c i d l a c t o n e , a 5-membered l a c t o n e ,
i s e x p l a i n e d p r i m a r i l y by i n c r e a s e i n s t r a i n a r i s i n g f rom bond
o p p o s i t i o n s i n a n e a r - t e t r a g o n a l t r a n s i t i o n s t a t e . I n g e n e r a l , a c i d -
a n d b a s e - c a t a l y z e d h y d r o l y s i s o f 6 - h y d r o x y h e x a n o i c a c i d l a c t o n e an d
7 - h y d r o x y h e p t a n o i c a c i d l a c t o n e i s s l o w e r t h a n t h a t f o r
46
5 - h y d r o x y p e n t a n o i c a c i d l a c t o n e . M ode l s o f t r a n s i t i o n s t a t e s of t h e
7 - and 8-mambercd l a c t o n e s i n d i c a t e t h a t t h e y a r e c row ded . S t r a i n s
a r e u n d o u b t e d l y c a u s e d by bond o p p o s i t i o n s and c o m p r e s s i o n s o f van
d e r Waals r a d i i . I t i s b e l i e v e d t h a t i n t r o d u c t i o n o f a t r i g o n a l
r i n g atom i n p l a c e o f a t e t r a h e d r a l o n e w i l l remove some o f t h e bond
o p p o s i t i o n and r e l i e v e s t r a i n .
3 - i i y d r o x y p r o p a n o i c a c i d l a c t o n e (b o t a - p r o p i o l a c t o n e ) s a p o n i f i e s
a t - 2 0 , 9 3 ° and - 0 . 0 3 ° a t r a t e s s i m i l a r t o t h a t of 5 - , 7- and 8-
merabered l a c t o n e s . The r e l a t i v e l y h i g h e n e r g y of a c t i v a t i o n f o r
s a p o n i f i c a t i o n o f b e t a - p r o p i o l a c t o n e i s n o t e x p e c t e d i f I - s t r a i n i n
t e r m s o f bond a n g l e d i s t o r t i o n , i s d o m i n a n t . I f t h e I - s t r a i n p r i n c i p l e
( 7 4 ) ca n be e x t e n d e d f r o m c a r b o c y c l i c t o h e t e r o c y c l i c s y s t e m s , i t i s
e x p e c t e d t h a t l a r g e s t r a i n r e l e a s e i s e f f e c t e d upon c o n v e r s i o n o f t h e
t r i g o n a l a tom o f t h e 4-membered r i n g t o a t e t r a h e d r a l o n e . how ever ,
M a t u s z a k a l s o i n d i c a t e s t h e d a n g e r s o f t h e I - s t r a i n t h e o r y i n t h a t i t
e m p h a s i z e s s t r a i n i n t r i g o n a l l y - h y b r i d i z e d r a t h e r t h a n t e t r a g o n a l l y -
h y b r i d i z e d a toms i n s m a l l r i n g s .
In g e n e r a l , i t i s o b s e r v e d (75 ) t h a t 6-membered l a c t o n e s w h ich
a r e s u b s t i t u t e d by m e t h y l g r o u p s h y d r o l y z e much more r a p i d l y t h a n do
t h e c o r r e s p o n d i n g 4 - , 5 - , and 7-mcmbered h o m o l o g s . The 4 - , 5 - , and
7-membered compounds h y d r o l y z e a t s i m i l a r r a t e s ; t h e g e n e r a l o r d e r
o f r e a c t i v i t y i s 4 > 7 > 5 .
I n c o n t r a s t t o s a p o n i f i c a t i o n o f l a c t o n e s , t h e o r d e r o f
r e a c t i v i t y o f u n s u b s t i t u t e d l a c t a m s i s 4 > 6 » 5 > 7 ( 7 6 ) . The r a t e s
47
o f s a p o n i f i c a t i o n o f t h e s e l a c t a m s do n o t d i f f e r g r e a t l y . S u b s t i
t u t i o n o f gera-d i m e t h y l g r o u p s i n l a c t a m s , i n g e n e r a l , d i m i n i s h e s
r a t e s o f r e a c t i o n . T h i s e f f e c t i s m o s t s t r o n g l y e x h i b i t e d i n 5 -
membered r i n g l a c t a m s c o n t a i n i n g g e i r - d i m e t h y l g ro u p s i n t h e 2 an d 4
p o s i t i o n s f r om t h e c a r b o n y l g r o u p .
The r e s u l t s f o r l a c t a m s a r e r a t i o n a l i z e d on t h e b a s i s o f
t r a n s i t i o n s t a t e s whicl i h a v e s i g n i f i c a n t l y more t e t r a h e d r a l c h a r a c t e r
t h a n t h o s e f o r l a c t o n e s a p o n i f i c a t i o n b u t w h ich a r e s t i l l i n t e r m e d i a t e
b e t w e e n t r i g o n a l and t e t r a g o n a l .
The e f f e c t s o f r i n g s i z e on t h e r a t e s o f a c i d - and b a s e -
c a t a l y z e d e n o l i z a t i o n o f hom ologous c y c l o a l k a n o n e s and c y c l o a l k y l
p h e n y l k e t o n e s h a v e b e e n d e t e r m i n e d ( 7 8 ) . T'ue r e a c t i v i t y o f c y c l o -
(78) H. S h e c h t e r and M. J . C o l l i s and R. U essy , Y. Okuzumi and A. Chen, J . Am. Chem. S o c . , 8^ , 2905 (1 9 5 2 ) .
a l k a n o n e s i n h y d r o c h l o r i c ac id - 9 0 % a c e t i c a c i d as a f u n c t i o n o f r i n g
s i z e i s : 6 > 3 > 5 > 7 > 4 ; t h a t f o r e n o l i z a t i o n by d e u t e r o x i d e i n
d i m e t h y l f o m a n i i d e - d e u t e r i u n o x i d e i s : 4 > 5 > 6 > 7. The r e a c t i v i t y
o r d e r f o r a c i d - c a t a l y z e d e n o l i z a t i o n o f c y c l o a l k a n o n e s i s i n t e r p r e t e d
p r i m a r i l y on t h e b a s i s o f d i f f e r e n c e s i n s t e r i c r e q u i r e m e n t s i n c o n
v e r s i o n o f t h e k e t o n e s t o t r a n s i t i o n s t a t e s w i t h e n d o c y c l i c
u n s a t u r a t e d c h a r a c t e r which i s h i g h l y d e v e l o p e d . The o r d e r f o r b a s e -
c a t a l y s i s i s r a t i o n a l i z e d on t h e b a s i s o f t h e d e g r e e o f s - c h a r a c t e r
48
o f t h e c a r b o n o r b i t a l i n v o l v i n g e n o l i z a b l c h y d r o g e n a s a f u n c t i o n
o f r i n g s i z e .
The e f f e c t s o f r i n g s i z e on t h e r a t e s o f f o r m a t i o n o f a n i o n s
f r o m a l k y l i d e n e c y c l o a l k a n e s and c y c l o a l k a n o n e s h av e b e e n i n v e s t i
g a t e d ( 7 9 ) . The i s o m e r i z a t i o n f rom e x o - t o e n d o - o l e f i n was e f f e c t e d
(79) A. S c h r i e s h e i m , R. J . M u l l e r and C. A. R ou e, J . Am. Chem. S o c . , 84 , 3164 ( 1 9 6 2 ) .
i n d i m e t h y l s u l f o x i d e u s i n g p o t a s s i u m t e r t - b u t o x i d e . The r e l a t i v e
o r d e r was; 4 > 5 > 8 > 7 > 6 . I t was p r o p o s e d t h a t r a t e i s c o n t r o l l e d
by a c h i e v e m e n t o f maximum p - p i - o v e r l a p i n t h e t r a n s i t i o n s t a t e . T h u s ,
t o fo rm an a l l y l i c a n i o n i c s y s t e m , t h e r e h y b r i d i z i n g p -b o n d h a s t o be
c o p l a n a r w i t h t h e e x i s t i n g p i - b o n d f o r maximum o v e r l a p . S i n c e t h e
4 - a n d 5-membered r i n g s a r e more p l a n a r i n t h e g round s t a t e , l e s s
e n e r g y i s r e q u i r e d t o a c h i e v e p l a n a r i t y i n t h e t r a n s i t i o n s t a t e
r e l a t i v e to t h e 6- mem be red r i n g . The 7 - an d 8-membered r i n g s y s t e m s
a r e l e s s r i g i d t h a n t h e 6-membered r i n g and t h u s a r e more r e a d i l y
o r i e n t e d i n t l ie t r a n s i t i o n s t a t e s f o r r e a c t i o n . S c h r i e s h e i m and c o
w o r k e r s p o i n t o u t t h e p a r a l l e l be tw een t h e r e l a t i v e r a t e s o f i s o m e r
i z a t i o n of e x o - t o e n d o - o l e f i n s and b r o m i n a t i o n o f t h e 4 - t h r o u g h
8-membered c y c l i c k e t o n e s . The p a r a l l e l i s e x p l a i n e d i n t h e same
c o n t e x t and a l i n e a r f r e e e n e r g y r e l a t i o n s h i p i s o b t a i n e d f o r t h e
r e a c t i o n s . The o r d e r and t h e i n t e r p r e t a t i o n f o r t h e r e l a t i v e r a t e s
o f b a s e - c a t a l y z e d b r o m i n a t i o n o f t h e c y c l i c k e t o n e s ( 4 > 5 > 3 > 7 > 6)
i s d i f f e r e n t f rom t h a t o f S h e c h t e r e_t al^. (7 8 ) f o r b a s e - c a t a l y z e d
49
d e u t e r a t i o u o f c y c l i c k e t o n e s (4 > 5 > 6 > 7 > 8 ) . I t i s o f i n t e r e s t
t h a t t h e r e l a t i v e o r d e r 4 > 5 h o l d s f o r b o t h s e r i e s and t h a t f o r t h e
4 - an d 5-membered r i n g k e t o n e s , t h e p o s t u l a t e o f S c h r i e s h e i m and
t h a t o f S h e c h t e r , a l t h o u g h o f d i f f e r e n t o r i g i n , a r e i n t h e same
d i r e c t i o n . T h u s , : n t h e 4 - and 5-membered r i n g k e t o n e s , t h e 4 -
membered r i n g i s e x p e c t e d t o r e a c t f a s t e r t h a n t h e 5-membered r i n g .
I t s h o u l d be n o t e d t h a t t h e p o s t u l a t e o f S h e c h t e r i s b a s e d on t h e
p r e m i s e t h a t t h e t r a n s i t i o n s t a t e i s c l o s e r t o r e a c t a n t s t l i a n e n o l a t e .
The p o s t u l a t e o f S c h r i e s h e i m i s a t r a n s i t i o n s t a t e e f f e c t i n w h i c h
t h e h i g h e n e r g y co m p lex i s c l o s e r t o e n o l a t e i n t e r m e d i a t e .
The s t e r i c and r i n g s i z e e f f e c t s on t h e r a t e s o f h y d r o l y s i s of
k e t a l s have b e e n s t u d i e d ( 8 0 ) . In a s o l v e n t 50% by w e i g h t d i o x a n e -
(80) M. M. K r e c v o y , C. R. Morgan and R. W. T a f t , J r . , J . Am. Chem. S o c . , 8 2 , 3064 ( 1 9 6 0 ) .
w a t e r , t h e a c i d - c a t a l y x e d h y d r o l y s i s r a t e s o f c y c l i c k e t a l s f o l l o w
t h e o r d e r : 7 > 5 > 6 > 4 . I f i t i s a s su m ed t h a t t h e t r a n s i t i o n
s t a t e h a s c o n s i d e r a b l e c a r b o n i u m i o n g e o m e t r y , t h e n f o r t h e 5-m embered
r i n g , t h e r e w i l l be r e l i e f o f t o r s i o n a l and e c l i p s i n g s t r a i n
a c c o m p a n i e d by an i n c r e a s e i n bond a n g l e s t r a i n ( 8 0 ) . H y d r o l y s i s o f
t h e 6-membered k e t a l i s a c com pan ied by an i n c r e a s e i n n o n - b o n d e d
i n t e r a c t i o n s o f r i n g h y d r o g e n s and a s m a l l i n c r e a s e i n t o r s i o n a l
s t r a i n f rom e c l i p s i n g o f t h e r e m a i n i n g -OR w i t h t h e two e q u a t o r i a l
h y d r o g e n a toms i n t h e a l p h a and a l p h a - p r i m e p o s i t i o n s on t h e r i n g .
50
In th e 7-ner;bered riii;; k e t a l , i t r, l i h . e l y t h a t t l i er e are t o r s i o n a l
a n d / o r an y l e s t r a i n e f f e c t s which are p a r t i a l l y r e l i e v e d by i n t r o
d u c in g a t r i g o n a l c a r b o n . The A-n.eir.l.Gred r i n g k e t a l i s e x p e c t e d to
undergo i n c r e a s e d bond a n g l e d i s t o r t i o n in th e a c t i v a t i o n p r o c e s s
and s l iould have a r e l a t i v e l y s l o w e r r e a c t i o n r a t e . The p r e d i c t e d
s e q u e n c e i s o b s erv e d . T h i s i s tl'.e i n v e r s e s e q u e n c e found i n th e
b o r o h y d r id e r e d u c t io n o f c y c l i c k e t o n e s ( 5 6 ) .
T’.ie r e l a t i v e a c i d i t i e s o f cy c l .o p ro p y l pkienyl s u l f o n e and
i s o p r o p y l riheny 1 s u l f o n e h av e been s t u d i e d (3 1 ) . Tlie e q u i l i b r i u m
(81) . h. Zim:a;orr.'.an and b . S . Thynga ra j a n , J . Am. Chem,S o c . , 32 , 2505 ( 1 5 ^ 0 ) .
cons tan. t f o r tlie r e a c t i o n ( l iq u a t io n 17) _
/ C " , _,Ch _^CHC l! I + C^li s o , , > SO, C' ! +
' " o n , " - ^Cn " OHg
C h r S O , C H " ^ ; ^ ( 1 7 )
i s n e a r l y one. In c o n t r a s t , n i t r o c y c l o p r o p a n e i s so r.;uch l e s s a c i d i c
than 2--i'.i t r o p r o p a n e , t h a t i t ’' / i l l n o t d i s s o l v e i n s t r o n g aqueous
b a s e ( 1 8 , 1 ? , 3 2 ) . The weak a c i d i t y i s a t t r i b u t e d to i n t e r n a l s t r a i n
(82) H. B. d a ; s and h . S h e c h t e r , i b i d . , 75 , 1382 ( 1 9 5 3 ) .
51
2i n v o l v e d i n f o r m a t i o n o f t h e sp - h y b r i d i z e d a n i o n ( 8 2 ) . I t i s c o n
c l u d e d t h a t i n t h e s u l f o n e c a r b a n i o n e l e c t r o n d e l o c a l i z a t i o n t h r o u g h
t h e s u l f o n e g r o u p i s n o t e x t e n s i v e and p l a n a r g e o m e t r y , u s u a l l y
a s s o c i a t e d w i t h s u c h s t a b i l i z a t i o n , i s n o t s i g n i f i c a n t .
The p r o p e r t i e s o f c a r b a n i o n s d e r i v e d f r o m c y c l o p r o p y l c y a n i d e s
h a v e bee n i n v e s t i g a t e d ( 8 3 , 8 4 ) . 2 , 2 - D i p h e n y l c y c l o p r o p y l c y a n i d e i s
(83) II. M. W a lb o r s k y and F. M. H o r n y a k , i b i d . , 7 7 , 6026( 1 9 5 5 ) .
(84) I b i d . , 7 8 , 872 (1956) .
r a c e m i z e d by d i i s o p r o p y l a m i d e i n e t h e r a t t e m p e r a t u r e s a s low a s
- 8 0 ° . T h i s r e s u l t i s o f i n t e r e s t b e c a u s e c e r t a i n t r i g o n a l c a r b a n i o n s
r e t a i n t h e i r c o n f i g u r a t i o n s and on t h e b a s i s o f I - s t r a i n t h e c y c l o
p ro p a n e r i n g s h o u l d p r e s e n t a b a r r i e r t o r a c e m i z a t i o n . I t was a l s o
found (83) t h a t t h e o p t i c a l l y a c t i v e m e t h y l e s t e r o f 2 , 2 - d i p h e n y l -
c y c l o p r o p a n e c a r b o x y l a t e r e t a i n e d 85-90% o f i t s o p t i c a l a c t i v i t y when
r e f l u x e d w i t h c o n c e n t r a t e d sod ium m e th o x id e i n m e t h a n o l . O p t i c a l l y
a c t i v e 2 , 2 - d i p h e n y l c y c l o p r o p y l cy a n id e i s r : c e m i z e d a p p r o x i m a t e l y
53 t im e s more s l o w l y t h a n i s m e t h y l e t h y l a c e t o n i t r i l e by sodium
m e th o x id e i n m e t h a n o l ( 8 4 ) . The e n t h a l p i e s o f a c t i v a t i o n o f t h e two
r e a c t i o n s d i f f e r , h o w e v e r , by on ly 3 k c a l .
The r a t i o o f d e u t e r i u m exchange t o r a c e m i z a t i o n o f 2 , 2 - d i -
p h e n y l c y c l o p r o p y l c y a n i d e i n d - m e t h a n o l - s o d i u r a m e t h o x i d e a t 7 5 . 7 °
52
i s 8 ,0 8 0 ( 8 5 ) . T h e s e r e s u l t s a r e i n t e r p r e t e d by a s s u m i n g t h a t t h e
(85) H. M. W a l b o r s k y , A. A. Y o u s s e f and J . M. M o t e s , J . Am, Chem. S o c . , 8 4 , 2467 ( 1 9 6 2 ) .
c y c l o p r o p y l c a r b a n i o n r e t a i n s i t s asymmetry and t h e r e i s a b a r r i e r
t o r e h y b r i d i z a t i o n o f t h e e l e c t r o n p a i r f r o m a h y b r i d i z e d o r b i t a l
t o a p - o r b i t a l ( I - s t r a i n ) .
I t has b e e n o b s e r v e d (86) t h a t f o r m a t i o n o f t h e l i t h i o
(86) II. M. W a l b o r s k y and A. E. Young, i b i d . , 8 6 , 3288 ( 1 9 6 4 ) .
d e r i v a t i v e and t h e G r i g n a r d r e a g e n t o f l - b r o m o - l - m e t h y l - 2 , 2 - d i p h e n y l -
c y c l o p r o p a n e o c c u r s w i t h r e t e n t i o n o f o p t i c a l a c t i v i t y .
RESULTS AND DISCUSSION
K i n e t i c s o f N e u t r a l i z a t i o n and I o n i z a t i o n C o n s t a n t s o f Homologous N i t r o c y c l o a l k a n e s
The i n i t i a l i n t e n t o f t h i s i n v e s t i g a t i o n was t o d e t e r m i n e
t h e r a t e c o n s t a n t s f o r n e u t r a l i z a t i o n o f t h e h o m o lo g o u s A- t h r o u g h
8-membered n i t r o c y c l o a l k a n e s by h y d r o x i d e i o n u n d e r p s e u d o - f i r s t
o r d e r c o n d i t i o n s i n 50% by vo lume 1 , 2 - d i m e t h o x y e t h a n e - w a t e r a t
0 . 0 0 ° .
I n t h i s l a b o r a t o r y , S to n e ( 1 8 ) , Traynham (2 4 ) and F l a n a g a n
(19) h a v e s t u d i e d t h e e f f e c t s o f r i n g s i z e on t h e s e c o n d - o r d e r r a t e
c o n s t a n t s ( k ^ ) f o r n e u t r a l i z a t i o n o f t h e ho mologous n i t r o c y c l o
a l k a n e s (8 7 ) i n 50% by volume 1 , 4 - d i o x a n e - w a t e r when b o t h r e a c t a n t s
(87) F o r f u r t h e r d i s c u s s i o n s e e H i s t o r y and T h e o r y .
w e re p r e s e n t i n e q u i m o l a r a m o u n t s . T h e s e r e a c t i o n s a r e v e r y r a p i d
( h a l f - l i v e s i n t h e r a n g e 0 . 5 - 5 m i n u t e s a t 0 . 0 0 5 M r e a c t a n t c o n c e n
t r a t i o n ) and F l a n a g a n g r e a t l y im p ro v e d on t h e e a r l y e x p e r i m e n t a l
t e c h n i q u e s d e v e l o p e d by S to n e a n d Tra ynham . F l a n a g a n ’ s k i n e t i c d a t a
gave f a i r l y goo d s e c o n d - o r d e r p l o t s up t o 65-75% c o m p l e t i o n o f
n e u t r a l i z a t i o n . I n t h e l a t e r s t a g e s o f r e a c t i o n , t h e s t r a i g h t l i n e s
53
c u r v e d downward. The c u r v a t u r e was a t t r i b u t e d t o s m a l l d i f f e r e n c e s
i n t h e i n i t i a l e q u a l i t y o f r e a c t a n t s o r t o t r a c e s o f i m p u r i t i e s .
The c o n d u c t o m e t r i c t e c h n i q u e s and m e t h o d s o f c a l c u l a t i o n of
t h e r a t e c o n s t a n t s , , f o r n e u t r a l i z a t i o n o f t h e n i t r o c y c l o a l k a n e s
was an e x t e n s i o n of t h a t u s e d p r e v i o u s l y (88) f o r n i t r o m c t h a n e ,
(88) S. H. Maron an d V. K. La Mer, J . Ara. Chem. S o c . , 6 0 , 2588 (1938).
n i t r o c t h a n e and 2 - n i t r o p r o p a n e ( T a b i c 1 ) . I t was a s sum ed t h a t t h e
n e u t r a l i z a t i o n s w ent t o c o m p l e t i o n . The e q u i l i b r i u m c o n s t a n t , Kc q .
f o r t h e n e u t r a l i z a t i o n p r o c e s s
K-
RgCHNO^ + OH R2C=N02 + H O (1 8 )
i s g i v e n by K = K_/K w h e r e K_ = a p p a r e n t i o n i z a t i o n c o n s t a n t of - eq . N w h
t h e n i t r o compound and = t h e i o n - p r o d u c t c o n s t a n t o f w a t e r . Tor
v a l u e s o f ( T a b le 6) i n t h e r a n g e 2 .09 X 10 ^ ( 2 - n i t r o p r o p a n e ) t o
-1 1 66 . 1 6 X 10 ( n i t r o m e t h a n e ) , t h e v a l u e o f K r a n g e s f rom 2 . 0 7 X 10e q .
3t o 6 . 0 7 X 10 r e s p e c t i v e l y . T h i s means t h a t i f s e c o n d - o r d e r k i n e t i c s
a r e b e i n g s t u d i e d ( i n w h i c h [OH ] = [R^CllXO^] = 0 . 0 0 1 M), t h e n a t
e q u i l i b r i u m , a p p r o x i m a t e l y 2.2% of t h e b a s e r e m a i n s . I f t h e m o l e c u l e s
a r e s i g n i f i c a n t l y l e s s a c i d i c t h a n 2 - n i t r o p r o p a n e , f o r example i n th e
-1 1r a n g e 10 , t h e n a t e q u i l i b r i u m u n d e r t h e same c o n d i t i o n s , 40% o f
t h e b a s e r e m a i n s . T h i s w o u ld c a u s e s e r i o u s e r r o r i n t h e v a l u e of
55
th e s e c o n d - o r d e r r a t e c o n s t a n t f o r th e n e u t r a l i z a t i o n o f a w e a k ly
a c i d i c m o l e c u l e .
One a d d i t i o n a l p o i n t i s of r e l e v a n c e to t l i i s d i s c u s s i o n . In
p a r t i a l l y n on-aqueous media , the v a l u e s o f K f o r weak a c i d s sucha
as n i t r o compounds s h o u l d d e c r e a s e as th e p e r c e n t a g e of d io x a n e
in c rea se s ; ( 3 9 ) . h o w ev er , the r a t i o K /K i s p r e d i c t e d to i n c r e a s ea w
v e r y s l i g h t l y w i t h th.c p erc e n ta g e o f d i o x a n e ( 8 9 ) .
(89) H. S. darned and h. 15. Owen, "The P h y s i c a l Checrlstry o f E l e c t r o l y t i c S o l u t i o n s " , Reinhold P u b l i s h i n g C or porat i on , hew Y ork ( 1 9 5 0 ) , p . 5U1.
T h e r e f o r e , i f in F lan agan 's work i t i s assumed th a t t h e v a l u e
o f h f o r t l ie 4 - through 8-nrembered n i t r o c y c l o a l k a n e s were i n th e h
- 8 - 9range 10 to 10 , u s i n g equal c o n c e n t r a t i o n s o f Oh and n i t r o
- 3compound i n the o r d er o f 2 to 5 X 1.0 M, the r e a c t i o n s s t u d i e d w i l l
p r o c e e d s u f f i c i e n t l y to com ple t io n to y i e l d good se c o n d - o r d e r r a t e
c o n s t a n t s f o r t h e s e p r o c e s s e s .
W i l l i a m s (57) found th a t p l o t s o f s e c o n d - o r d e r k i n e t i c da ta
f o r n e u t r a l i z a t i o n o f primary n i t r o compounds i n 50% by volume 1 , 4 -
d i o x a n e - w a t c r were no t l . inear to even 50% c o m p l e t i o n . This was due
to th e f a c t t h a t primary n i t r o compounds ( f o r example n i t r o m e t h a n e )
were to o weakly a c i d i c . To o b t a i n a c c u r a t e s e c o n d - o r d e r r a t e con
s t a n t s f o r n e u t r a l i z a t i o n of primary nd.tro , W i l l i a m s employed o t h e r
t e c h n i q u e s and d e r i v e d anoth er mat hem ati ca l t r e a tm e n t for th e k i n e t i c
d a t a .
56
ï a e new tecl in ique s t u d i e d sccc ' sd-order k i n e t i c s eniploying
e x c e s s n i t r o compound. The i n i t i a l c o n c e n t r a t i o n o f n i t r o a l k a n e
was 1 . 7 9 to around 3 t i n e s g r e a t e r t'nan t i ic b a s e c o n c e n t r a t i o n . An
e x p r e s s i o n was d e r i v e d f o r the seconJ. -order d i s a p p e a r a n c e o f b a s e
and n i t r o compound a s a f u n c t i o n of t ir .e where th e i n i t i a l r a t i o
o f r e a c t a n t c o n c e n t r a t i o n s i s known. The k i n e t i c d a t a ob ta ine d gave
l i n e a r p l o t s to g r e a t e r than 75% c o i r p l c t io n and r a t e c o n s t a n t s whic'n
were f<ar more c o n s i s t e n t .
The p r e s e n t i n v e s t i g a t i o n s thus i n i t i a l l y fo c u s e d on d e v e l o p
i n g t c ch n ic iu cs by w’nic'n th e r a t e s o f n e u t r a l i z a t i o n o f n i t r o c y c l o
a l k a n e s by h y dr o x id e i o n cou.ld be determined under p s e u d o - f i r s t o rd er
c o n d i t i o n s a c c o r d i n g to t h e r e l a t i o n
- d b / d t - d;-:/dt - k^b (19)
where - d b / d t - t'ne r a t e o f d i s a p p e a r a n c e o f b a s e (h y d ro x id e i o n ) ,
b = th e c o n c e n t r a t i o n o f b a s e a t t i n e , t , and t h e p s e u d o - f i r s t
ord er r a t e c o n s t a n t = k a (a - c o n c e n t r a t i o n o f a c i d , or n i t r o
compound) . S u b s t i t u t i n g an e x p r e s s i o n f o r c o n c e n t r a t i o n in terms
of c e l l r e s i s t a n c e i n t o E qu a t io n 19 and i n t e g r a t i n g y i e l d s Equation
20 .
l n ( l / R - 1 /R) = - k t + l n ( l / R - 1 /R ) (20)o 1 o ^
57
T h e r e f o r e , a p l o t o f l o g (1/R^ - 1/R) v e r s u s t y i e l d s a s t r a i g h t l i n e
whose s l o p e = - k ^ / 2 . 3 0 3 = - k ^ a / 2 . 3 0 3 . T h i s p r o c e d u r e i s d i s c u s s e d i n
more d e t a i l i n th e E x p e r i m e n t a l S e c t i o n .
I f t h e s e r e a c t i o n s were not g o i n g to c o m p l e t i o n a prime
o b j e c t i v e was to e s t a b l i s h an a c c u r a te r a t e c o n s t a n t f o r n e u t r a l i z a t i o n
o f n i t r o c y c l o b u t a n e . S i n c e n i t r o c y c l o b u t a n e n e u t r a l i z e s r a p i d l y and
i t s i o n i z a t i o n c o n s t a n t m ig h t be c o n s i d e r a b l y s m a l l e r t'nan t h a t o f
i t s h i g h e r i iornologs , t'ne r a t e c o n s t a n t m ig h t b e s e r i o u s l y i n e r r o r
compared to t'aat o f t'ne hig'ner n i t r o c y c l o a l k a n e s .
In t'ne p r e v i o u s s e c o n d - o r d e r k i n e t i c s y s t e m s , th e c o n c e n
t r a t i o n s o f base and n i t r o compound were a p p r o x i m a t e l y Ü.Ü05 M. In
o rd er to c o n v e r t t h e p r e v i o u s sys tem to one o b e y i n g p s e u d o - f i r s t
o rd er ' n i n e t i e s , th e c o n c e n t r a t i o n o f n i t r o compound would have to be
i n c r e a s e d a t l e a s t 1 0 - f o l d . I f h ydrox id e i o n c o n c e n t r a t i o n s i n t h e s e
s y s t e m s -mere in t ’ne o r d e r o f Ü.05 th e r a t e s o f n e u t r a l i z a t i o n would
be too f a s t to m e a s u r e . I t was t h e r e f o r e n e c e s s a r y to d e v e l o p t e c h
n i q u e s i n v/iiich l o w e r c o n c e n t r a t i o n s o f b a s e c o u l d be used .
A new c e l l was t i ius d es ig ne d ( F i g u r e 6 ) 'which c o u ld e a s i l y
d e t e c t (w i t i i i n th e r e s i s t a n c e range o f t'*ie b r i d g e ) s m a l l - amounts o f
b a s e (10 ^ j ) as w e l l a s t'ne change in t'ne i o n i c s p e c i e s . T his c e l l
was o f s m a l l e r volume and employed l a r g e e l e c t r o d e s spaced much
c l o s e r t o g e t h e r tlinn c e l l s p r e v i o u s l y u s e d . With th e c o n c e n t r a t i o n
o f n i t r o compound (around 0 . 0 0 5 h) in 3 0 - f o l d e x c e s s , p s e u d o - f i r s t
o r d e r k i n e t i c d a ta and p l o t s l . inear to 90% c o m p l e t i o n were o b t a i n e d .
58
I n p r e v i o u s e x p e r i m e n t a l t e c h n i q u e s , k i n e t i c s o l u t i o n s o f
s t a n d a r d b a s e and s t a n d a r d n i t r o compound w e r e p r e p a r e d . The
p r e p a r a t i o n o f a s t a n d a r d k i n e t i c s o l u t i o n o f n i t r o a l k a n e r e q u i r e d
t i m e and i t r e q u i r e d s e v e r e ] grams o f v a l u a b l e m a t e r i a l . I n some
c a s e s , v e r y l i t t l e n i t r o compound was a v a i l a b l e . T h e r e f o r e , i n t h e
p r e s e n t s t u d i e s , t h e n i t r o compound was i n j e c t e d d i r e c t l y i n t o t h e
b a s i c k i n e t i c s o l u t i o n . A c c u r a t e r e p r o d u c i b l e vo lum es o f r e a c t a n t
w e r e o b t a i n e d u s i n g t l ie H a m i l to n M i c r o l i t e r s y r i n g e (701-N) o r t h e
R o g e r Gi I r o n t I n d u s t r i e s M i c r o m e t e r s y r i n g e .
One o t h e r p r o b l e m i n t h e d e t e r m i n a t i o n o f a c c u r a t e r a t e c o n
s t a n t f o r n e u t r a l i z a t i o n o f n i t r o c y c l o b u t a n e by p r e v i o u s w o r k e r s i n
t h i s l a b o r a t o r y w^as p o i n t e d o u t by F l a n a g a n , He a t t r i b u t e d t h e
d i s a g r e e m e n t among t h e v a r i o u s i n v e s t i g a t i o n s t o t h e f a c t t h a t e a r l y
t e c h n i q u e s a l l o w e d a t e m p e r a t u r e i n c r e a s e w h i l e m i x in g t l ie r e a c t a n t s .
F o r f a s t r e a c t i o n s , a r i s e i n t e m p e r a t u r e w i l l c a u s e t h e r e a c t i o n to
go e v e n f a s t e r . U s i n g t h e p r e s e n t t e c l m i q u e s , t h e volume o f n i t r o
co m pound , a t room t e m p e r a t u r e , v/hich was i n j e c t e d i n t o a t h e r m o -
s t a t e d s o l u t i o n a t 0 . 0 0 ° X7as s m a l l . T h i s w o u l d m i n i i r i z e any t e m p e r
a t u r e i n c r e a s e ev e n more t h a n t h e p r o c e d u r e o f F l a n a g a n i n w h i c h a
r e l a t i v e l y l a r g e v o lu m e ( a p p r o x i m a t e l y 10 m i l l i l i t e r s p e r r u n ) o f
s t a n d a r d s o l u t i o n o f n i t r o c y c l o a l k a n e was i n j e c t e d i n t o t h e k i n e t i c
s o l u t i o n o f s t a n d a r d b a s e by means o f a h y p o d e r m i c s y r i n g e . In
a d d i t i o n , b e c a u s e p s e u d o - f i r s t o r d e r k i n e t i c s w e re b e i n g s t u d i e d ,
t h e i n i t i a l r e s i s t a n c e d i d n o t have t o be known. I t was o n l v
59
n e c e s s a r y to know . T h e r e f o r e , an a d d i t i o n a l fev; moments ( 0 . 3 to
0 . 7 m i n u t e s ) c o u ld be a l l o w e d a f t e r i n j e c t i n g t h e n i t r o compound
b e f o r e b e g i n n i n g t o r e c o r d r e s i s t a n c e m e a s u r e m e n t s as a f u n c t i o n o f
t i m e . T h i s t ime l a p s e p r o v i d e d a d d i t i o n a l i n s u r a n c e t h a t t h e s y s t e m
was a t t h e r m a l e q u i l i b r i u m .
The use o f p s e u d o - f i r s t ; o r d e r k i n e t i c s o f f e r s t h e a d d i t i o n a l
a d v a n t a g e t h a t t h e d a t a i s e a s i e r t o p r o c e s s t h a n s e c o n d - o r d e r d a t a
a s i s e v i d e n t f rom the. e x p l a n a t i o n o f E q u a t i o n 19.
The s o l v e n t c h o s e n i n t h i s i n v e s t i g a t i o n was 50% by vo lum e
1, 2 - d i m e t l i o x y c t h a n e - w n t e r . 1 , 2 -D in iC th o x y e th an e i s p r e f e r r e d o v e r
d i o x a n e wtiich p r e v i o u s i n v e s t i g a t o r s had c h o s e n b ec au s e i t i s e a s i e r
t o ke ep p u r e .
The r e s u l t s o f t h i s s t u d y a r e c o m p i l e d i n Tab le 10 . I t i s
o b s e r v e d t h a t t h e r e l a t i v e o r d e r o f r e a c t i v i t y as a f u n c t i o n o f r i n g
s i z e i s 4 > > 5 > 7 > 8 > 6 , t h e same s e q u e n c e o b se rved i n p r e v i o u s
i n v e s t i g a t i o n s ( 1 8 , 1 9 , 2 4 ) . The. r a t e c o n s t a n t s i n t h i s s t u d y a r e
s l i g h t l y g r e a t e r t h a n t h o s e o b t a i n e d by F l a n a g a n (19) e x c e p t t h a t
f o r n i t r o c y c l o b u t a n e w h i c h i s s m a l l e r by a s i g n i f i c a n t m a r g i n . The
d i s c r e p a n c i e s a r c n o t s e r i o u s r e l a t i v e e i t h e r to F l a n a g a n o r Traynham
(2 4 ) c o n s i d e r i n g t h e f a c t t h a t t h e s o l v e n t s and the t e c h n i q u e s a r e
n o t t h e same.
I t i s o f s i g n i f i c a n c e t h a t i n each s u c c e s s i v e s t u d y , t h e r a t e
c o n s t a n t f o r n e u t r a l i z a t i o n o f n i t r o c y c l o b u t a n e i s found t o b e l e s s
t h a n p r e v i o u s l y . F l a n a g a n a t t r i b u t e d t h i s t r e n d to e x p e r i m e n t a l
TABLE 10
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOALKANES WITH THE SODIUH CONJUGATE BASE OF THE SOLVENT AT 0 . 0 0 °
Compound50% 1 , 2 -
U im et l ' . oxye thano-w a t e r
I
M e t h a n o l
1 . - m i n . )
E t h a n o l E t h y l e n e G l y c o l
2 - N i t r o p r o p a n e 1 1 . 0 1.A6 3 2 .9 2 . 3 7
N i t r o c y c l o p r o p a n e 0 . 0
N i t r o c y c l o b u t a n e 143 2 6 . 0 291 ( E s t . ) 1 8 . 8
N i t r o c y c l o p e n t a n e 4 1 . 9 7 .6 7 132 7 . 6 3
N i t r o c y c l o h c x a n e 8 . 1 1 2 . 1 3 2 4 . 5 1 . 3 9
N i t r o c y c l o h e p t a n e 2 4 . 2 5 . 5 1 7 9 . 2 5 . 4 2
N i t r o c y c l o o c t a n e 1 8 . 8 4 . 4 0
4 > > 5 > 7 > 8 >
5 8 . 2
6
2 .7 9
C'o
61
t e c h n i q u e s u s e d by S to n e (1 8 ) end Traynham (24) i n vdi ich t h e c o n
d u c t i v i t y c e l l s w e re removed f ro m t h e b a t h p e r i o d i c a l l y t o i n s u r e
m i x i n g . The r e s u l t i n g t e m p e r a t u r e i n c r e a s e w o u ld p r o d u c e a r a t e
c o n s t a n t t h a t i s too l a r g e , and t h e d i s c r e p a n c y w o u ld be g r e a t e r t h e
more r a p i d t h e r e a c t i o n , B oth S t o n e and Traynham f o u n d t l t a t t h e
e a r l y p o i n t s o f a k i n e t i c r u n d e v i a t e d f rom s t r a i g h t - l i n e p l o t s .
F l a n a g a n d i d n o t f i n d su ch d e v i a t i o n s e m p lo y in g t h e t e c h n i q u e s and
c e l l s w h ich h e d e s i g n e d .
B e c a u s e t h e e x p e r i m e n t a l t e c h n i q u e s o f t h i s s t u d y s h o u l d
m i n i m i z e t e m p e r a t u r e e f f e c t s more t h a n t h e p r o c e d u r e o f F l a n a g a n ,
t h e s m a l l e r r a t e c o n s t a n t f o r n i t r o c y c l o b u t a n e p r e s e n t l y o b t a i n e d
i s e x p e c t e d . The c o m p l e t e n e s s o f thc :se p r o c e s s e s wrien t h e r e a c t a n t s
a r e i n i t i a l l y p r e s e n t i n e q u a l m o l a r amounts h a s b e e n q u e s t i o n e d ( 5 7 ) .
I f n e u t r a l i s a t i o n o f n i t r o c y c l o b u t a n e was n o t p r o c e e d i n g t o c o m p l e t i o n ,
t h e r a t e c o n s t a n t d e t e r m i n e d by F l a n a g a n i s low ( 1 9 ) . Thus , t h e r a t e
c o n s t a n t fo u n d i n t h e p r e s e n t s t u d y s h o u l d h a v e b e e n g r e a t e r t h a n
t h a t p r e v i o u s l y n o t o n l y b e c a u s e o f t h e t e c h n i q u e s and t h e s o l v e n t
u s e d , b u t b e c a u s e t h e r e a c t i o n i s more c o m p l e t e .
With t h e e x c e p t i o n o f n i t r o c y c l o b u t a n e , t h e r e l a t i v e r e a c t i v
i t i e s o f t h e c y c l i c n i t r o compounds (5 > 7 > 8 6) may be c o r r e l a t e d
w i t h t h e g e n e r a l p r i n c i p l e s o f I - s t r a i n t h e o r y (66) w h ich i s b a s e d
upon t h e r e l a t i v e s t a b i l i t i e s o f t r i g o n a l v e r s u s t e t r a h e d r a l a toms
o f a c a r b o c y c l i c r i n g . T h e r m o d y n a m i c a l l y , an e x o - d o u b l e bond i s
62
more s t a b l e i n a 5 - than a 6-membcred A r e a c t i o n in wi i ica an
e x o - doub le bond i s formed s h o u ld be favo red i n a cy c lo p er . t a ne b ut
n o t i n a c y c lo h e x a n e s y s t e m , i f th e t r a n s i t i o n s t a t e f o r r e a c t i o n
r e f l e c t s t r i g o n a l c h a r a c t e r . S i m i l a r l y , a 7-membered r in g w i l l
r e a c t f a s t e r than a G-ip.cmbcro.d r i n g due to r e l i e f o f t o r s i o n a l
s t r a i n . I t i s a l s o e x p e c t e d th e t r i g o n a l b o nd ing d ur in g t r a n s i t i o n
w i l l reduce c o m p r es s io n o f van der Waal' s r a d i i and bond o p p o s i t i o n s
i n 8-membered r i n g s c a u s i n g n i t r o c y c l o o c t a n e to n e u t r a l i z e , f a s t e r
than n i t r o c y c l o i i e . x a n e . The A- and e s p e c i a l l y tb.e 3-mcmbered n i t r o -
cyclonl 'na.ne would r e a c t more s l o w l y than n i t r o c y c l o l i e x a n e b e c a u s e
o f t'ne i n c r e a s e d a n g l e defor i .rat ion s t r a i n , h o w ev e r , i t has been
o b s e r v e d by a l l w o r k e r s i n t h i s l a b o r a t o r y t h a t n i t r o c y c l o b u t a n e
n e u t r a l i z e s many tim.es f a s t e r t!ian n i t r o c y c l o p e n t a n e . To a c c o u n t f o r
t h i s unu su a l r e a c t i v i t y , i t has been proposed (19 ) t h a t s o l v a t i o n
p l a y s an im porta nt r o l e , p a r t i c u l a r l y i n s m a l l , r i g i d r i n g s ( c y c l o -
b u t a n c s and c y c l o p r o p a n c s ) and t h a t the i m p o r ta n ce o f bond o p p o s i t i o n
f o r c e s i s mucli g r e a t e r i n c y c l o b u t y l d e r i v a t i v e s tVi.an has been
p r e v i o u s l y su pposed .
B ecau se o f u n u s u a l r e a c t i v i t y of n i t r o c y c l o b u t a n e and t h e o v e r
a l l k i n e t i c r e s u l t s w i t h n i t r o c y c l o a l k a n e s , i t was o f i n t e r e s t to
d ete r m in e apparen t i o n i z a t i o n c o n s t a n t s o f th e c y c l i c n i t r o compounds
a s a f u n c t i o n o f r i n g s i z e ( 3 - through 8-membered r i n g s . E quati on 2 1 ) .
T hese measurements \ ;ero made i n 33.3% by w e ig l i t m e th a n o l -w a t er by
63
C=NOOH + H O (21)
poten tiom etr ic t i t r a t i o n o f an a liqu ot of standard s o lu t io n o f n i t r o
compound with a l iq u o ts o f standard sodium hydroxide. The a l iq u o ts o f
standard base contained e i t h e r 1 /4 , 1 /2 , or 3 /4 eq u iva len ts o f sodium
hydroxide. The method and techniques are s im ila r to that used
p r e v io u s ly (42) and are described in d e t a i l in the Experimental
S e c t io n .
The re su lts of the present in v e s t ig a t io n are compiled in Table
11 and in Tables 48 through 52 in the appendix. I t i s observed for
nitrocyclobutane (Table 48) that the pH* (pH s c a le in 33.3% by w eight
methanol-water) o f a p a r t i a l l y neutra lized s o lu t io n decreases with
time (the longest o b serva tion was two days) . The most p rec ise va lu e
o f Kjj for n itrocyclobutane i s obtained from the measurements taken,
a t the estimated time fo r complete rea c t io n between the n itro
compound and hydroxide io n , a t the 1 /4 , 1 /2 and 3 /4 n e u tr a l iz a t io n
p o in t . I t is observed for h igher n itro cy c lo a lk a n es that pH* d ecreases
w ith time although not as rap id ly (9 0 ) . The d ecrease in pH i s
a t tr ib u te d to decomposition o f cy c lob u tan en itron ate . I t has been
found (91) the n itro n a te anion of 2-nitropropane, 1-nitropropane and
(90) See for example the data on n itro cy c lo h ex a n e , Table
(91) G. A. R u s s e l l , J . Am. Chem. S o c . , 76, 1595 (1954).
TAIiLE 11
ACIÜ DISSOCIATION CONSTANTS OF NITROCYCLOALKANES IK 33.3% BY HEIGHT MLTllANOL-HATLR AT 2 5 . 0 °
Compound K X 10^^
N i t r o c y c l o b u t a n e 2 . 9 6
Ni t r Ù cy c ].o p cn t ana 122
N i t r o c y c l o h e x n n c 1 2 . 1
N i t r o c y c l o h e p t a n e 225
N i t r o c y c ] o o c t a n e 554
8 > 7 > 5 > 6 > 4
65
n i t r o c y c l o h e x a n e r e a c t w i t h ox ygen a u t o c a t a l y t i c a l l y i n a q u e o u s s o d i u m
h y d r o x i d e a t 25° t o g i v e , among o t h e r p r o d u c t s , n i t r i t e io n a n d o r g a n i c
a c i d s . The f o r m a t i o n o f o r g a n i c a c i d s i n t h e p r e s e n t s y s t e m s wou ld
e x p l a i n t h e d e c r e a s e i n pH*. F o r m a t i o n o f o r g a n i c a c i d s and n i t r i t e
i o n would a c c o u n t f o r t h e o b s e r v e d d e c r e a s e i n c e l l r e s i s t a n c e w h ich
i s c h a r a c t e r i s t i c o f t h e k i n e t i c s t u d i e s d i s c u s s e d p r e v i o u s l y .
I t i s o b s e r v e d t h a t v a l u e s f o r d e r i v e d f rom d a t a on 1 / 4
and 1 / 2 n e u t r a l i z e d s y s t e m s a r e m os t c o n s i s t e n t . F o r t h i s r e a s o n ,
e x c e p t f o r n i t r o c y c l o b u t a n e , t h e v a l u e s r e p o r t e d f o r i n T a b l e 11
a r e a v e r a g e s t a k e n f r om r u n s a t e i t h e r 1 /4 o r 1 / 2 ( o r b o th ) n e u t r a l
i z a t i o n . P r e v i o u s l y (4 2 ) t h e a p p a r e n t i o n i z a t i o n c o n s t a n t f o r
s i m p l e n i t r o a l k a n e s w e re d e t e r m i n e d froKi s y s t e m s t i t r a t e d t o 1 / 4
n e u t r a l i z a t i o n . Even w i t h t h e s o u r c e s f o r e r r o r t h a t e x i s t i n t h e s e
s y s t e m s , i t a p p e a r s f a i r l y c e r t a i n t l i a t t h e r e l a t i v e a c id s t r e n g t h s
o f t h e 4- t h r o u g h 8-m embered c y c l i c n i t r o compounds a r e 8 -• 7 > 5 >
6 > 4 .
I t i s o f s p e c i a l i n t e r e s t t o t h e p r e s e n t i n v e s t i g a t i o n t h a t
t h e rm o d y n a m i c a c i d i t i e s ( T a b l e 12) o f h o m o lo g o u s n i t r o c y c l o a l k a n e s
a r e c o r r e l a t e d by I - s t r a i n t h e o r y (8 > 7 > 5 > 6 > 4 > > 3 ) . I t i s
e x p e c t e d t h a t 5 - , 7 - an d 8-membered n i t r o c y c l o a l k a n e s w i l l be s t r o n g e r
( E q u a t i o n 18) t h a n n i t r o c y c l o h e x a n e . C o n v e r s i o n o f a t e t r a h e d r a l
c a r b o n to t r i g o n a l s h o u l d r e l i e v e bond o p p o s i t i o n s i n 5 - and 7 -
membered r i n g s and a l s o v an d e r W a a l ' s f o r c e s i n n i t r o c y c l o o c t a n e
( 9 2 ) . T r i g o n a l g e o m e t r y w i l l i n c r e a s e bond o p p o s i t i o n s i n t h e
6 G
(92) N. L. A l l i n g e r , J . Am. Chcm. S o c . , _81, 5727 (1959)
5-m embercd r i . n ^ . I n t u r n , n i t r o c y c l o h e x a n e w i l l be a much s t r o n g e r
a c i d t h a n n i t r o c y c l o b u t a n e t h a n n i t r o c y c l o p r o p a n e . F o r m a t i o n o f a
t r i g o n a l c a r b o n i n a 4 - and 3-nie;:;bered r i n g shoul .d r e s u l t i n a m a j o r
i n c r e a s e i n bond a n g l e d i s t o r t i o n s t r a i n and t h u s b o t h n i t r o c y c l o
b u t a n e and n i t r o c y c l o p r o p a n e a r c e x p e c t e d t o be w e a k e r a c i d s t h a n
n i t r o c y c l o h e x a n e .
B r o n s t c d c o r r e l a t i o n docs n o t e x i s t b e t w e e n a c i d s t r e n g t h s
and r a t e c o n s t a n t s f o r n e u t r a l i z a t i o n (4 >> 5 > 7 > 8 > G >> 3) o f
n i t r o c y c l o a l k a n e s . A l i n e a r f r e e e n e r g y r e l a t i o n s h i p i s e x p e c t e d
when t h e s t r u c t u r e o f t h e t r a n s i t i o n s t a t e f o r n e u t r a l i z a t i o n and
t h e s t r u c t u r e o f t h e c y c l o a l k a n c n i t r o n a t e a n i o n r e s e m b l e one a n o t h e r
( 5 6 ) . The q u a l i t a t i v e c o r r e l a t i o n b e t w e e n th e rm o d y n am ic and k i n e t i c
a c i d i t i e s (3 , 7, 5 > 6) i s p r e d i c t e d by I - s t r a i n t h e o r y . The a b s e n c e
o f a q u a n t i t a t i v e c o r r e l a t i o n be tw een t h e 5 - , 7 - , and 8-membcrcd
r i n g s (K : 8 > 7 > 5 ; k : 5 > 7 ; 8) may r e s u l t f rom d i s s i m i l a rN k
t r i g o n a l g e o m e t r y i n t h e r e s p e c t i v e t r a n s i t i o n s t a t e s f o r n e u t r a l
i z a t i o n o r f rom o t h e r f a c t o r s ( su c h a s t r a n s a n n u l a r i n t e r a c t i o n s )
o p e r a t i v e i n t h e 7 - and 8-membered r i n g s .
To e x p l a i n t h e u n u s u a l r e a c t i v i t y o f n i t r o c y c l o b u t a n e , a
number o f f e a t u r e s o f 4-membered r i n g s m u s t b e c o n s i d e r e d . The
e n t h a l p y o f a c t i v a t i o n f o r n i t r o c y c l o b u t a n e i s c o m p a r a b l e t o t h a t f o r
6/
t h e h i g h e r n i t r o c y c l o a l k a n e s b u t i t s e n t r o p y o l r e a c t i o n i s . s i g n i f
i c a n t l y l o w e r ( 1 9 ) . I f i t i s e x p e c t e d t h a t bond a n g l e d e f o r m a t i o n
s t r a i n w i l l c a u s e a m a j o r i n c r e a s e i n e n t h a l p y o f r e a c t i o n , i t i s
o b v i o u s t h i s e f f e c t i s b e i n g c o m p e n s a t e d i n some m a n n e r . Above, i t
was s u g g e s t e d t h a t t h e t r a n s i t i o n s t a t e s f o r n e u t r a l i z a t i o n may h a v e
d i f f e r i n g d e g r e e s o f t r i g o n a l c h a r a c t e r a s a f u n c t i o n o f r i n g s i z e .
2I f s o , n i t r o c y c l o b u t a n e may h a v e l e s s sp g e o m e t r y t h a n i t s h i g h e r
homologs due t o i n c r e a s e bond a n g l e d e f o r m a t i o n s t r a i n . I n d e p e n d e n t
o f o t h e r s t a b i l i z i n g f a c t o r s , t h i s t r a n s i t i o n s t a t e wou ld be of
h i g h e r e n e r g y t h a n t h o s e o f l a r g e r r i n g s . Tiie d e c r e a s e d d e l o c a l
i z a t i o n , h o w e v e r , s h o u l d be p a r t i a l l y c o m p en s a t ed by g r e a t e r s -
c h a r a c t e r i n t h e c a r b o n - h y d r o g c n bond o f s m a l l r i n g s . A d d i t i o n a l
f e a t u r e s may a l s o c o m p e n s a t e t h e more e n e r g e t i c c y c l o b u t a u e n i t r o n a t e
f o r m i n g i n t r a n s i t i o n . A-Mei:ibered r i n g s a r e s l i g h t l y p u c l t e r c d (93)
(93) E. L. E l i e l , N. L. A l l i n g e r , S. S. A n g y a l and J . A. M o r r i s o n , " C o n f o r m a t i o n a l A n a l y s i s " , I n t e r s c i c n c c P u b l i s h e r , 'dev/ Y o rk , 1965 , pp . 1 9 9 - 2 0 0 .
t o r e l i e v e t o r s i o n a l s t r a i n f rom bond o p p o s i t i o n s . The p u c k e r i n g
e x i s t s d e s p i t e i n c r e a s e d bond a n g l e d i s t o r t i o n . As t h e t r a n s i t i o n
s t a t e d e v e l o p s r e m o v a l o f t h e p r o t o n a l l o w s t h e r i n g t o become more
p l a n a r r e l i e v i n g t h e p u c k e r i n g and a s s o c i a t e d a n g l e d i s t o r t i o n .
T h u s , as t h e n i t r o g r o u p a ssum es t r i g o n a l c h a r a c t e r w i t h a s s o c i a t e d
a n g l e d e f o r m a t i o n s t r a i n , t h e r i n g i s beco m in g p l a n a r d e c r e a s i n g t i ie
68
angle deformation s t r a in presen t in the ground s t a t e of the 4-membered
r in g . The ground s t a t e o f n itrocyc lobu tane conta in s a d e s ta b i l i z in g
1,3-hyd rogen-hydrogen-in teraction . Deuterium iso to p e e f f e c t s (19)
su ggest that in the t r a n s i t io n s t a t e for n e u tr a l iz a t io n of n i t r o
compounds the carbon-hydrogen bond i s h ig h ly broken and the bond
between the base and the proton i s a lso weakly formed. Thus, i t i s
a n t ic ip a te d that the 1 ,3 - in t e r a c t io n i s being removed in t r a n s i t io n .
A l l these e f f e c t s r e s u l t in increased ^ f le x ib i l i t y o f the n i t r o c y c lo
butane substrate in the a c t iv a te d complex and l e s s n egative (more
favorab le entropy of a c t iv a t i o n ) .
Two features o f n itrocyc lob u tane are expected to con tr ib u te
s i g n i f i c a n t l y to favorable entropy of a c t iv a t i o n . In i t s ground s ta te
nitrocyc lobutane has i t s a c id i c hydrogen h ig h ly exposed. Thus,
c o l l i s i o n s of n itrocyc lobutane with hydroxide ion r e s u l t in g in geometry
s u i t a b le to reaction are more probably r e l a t i v e to other c y c l i c n itro
compounds. Also, in th e t r a n s i t io n s t a t e for n e u tr a l i z a t io n o f n i t r o
cyclobutane, the Cg-C^-C^ bond angle may be n ear ly 90® and that
between the n itro group and the plane d ef in ed by carbon atoms C^-C^-C^
may a ls o be almost 90° . N itrocyc lobutane, th u s, may have almost
p e r fe c t geometry to n e u tr a l iz e without e x te n s iv e d e lo c a l i z a t i o n , i f
any a t a l l , leaving the in c ip ie n t anion to r e s id e in a s p h e r ic a l ly
symmetrical s - o r b i t a l and the bonds of the r ing atom undergoing
t r a n s i t io n to have appropriate p-geometry.
69
N i t r o c y c l o b u t a n e i s a s m a l l r i g i d m o l e c u l e and i t i s e x p e c t e d
t o be more s o l v a t e d i n t h e g rou nd and i n t h e t r a n s i t i o n s t a t e t h a n
i t s h o m o l o g s . S o l v e n t s t a b i l i z a t i o n o f t h e i n c i p i e n t c y c l o b u t a n e -
n i t r o n a t e i n t h e t r a n s i t i o n s t a t e v i i l l l o v e r t h e en e rg y o f a c t i v a t i o n ,
r e l a t i v e t o l a r g e r c y c l i c n i t r o compounds . h o w e v e r , t h e d e c r e a s e d
s o l v a t i o n i n t h e t r a n s i t i o n s t a t e o f h i g h e r ho mologs a l l o w s t h e s e
s y s t e m s t o become more ra nd om. T h u s , a c t i v a t i o n e n t r o p y s h o u l d be
more p o s i t i v e f o r l a r g e r r i n g s y s t e m s . F o r th.e A-membered r i n g , t h e
a n t i c i p a t e d g r e a t e r s o l v a t i o n o f t h e a c t i v a t e d complex s h o u l d make
a n e g a t i v e c o n t r i b u t i o n t o t h e e n t r o p y o f a c t i v a t i o n . The f a v o r a b l e
a c t i v a t i o n e n t r o p y o b s e r v e d f o r n i t r o c y c l o b u t a n e must r e s u l t f rom
i n c r e a s e d f r e e d o m o f t h e s y s t e m from o t h e r s o u r c e s which m ere t h a n
co m p e n s a t e any r e s t r i c t i o n a c q u i r e d t h r o u g h s o l v a t i o n . The m a j o r
c o n t r i b u t i o n o f s o l v e n t i s t h e n s e e n a s r e d u c i n g a c t i v a t i o n e n t h a . l p y .
S i n c e t h e r e l a t i v e r a t e s o f n e u t r a l i z a t i o n of t h e h o m o lo g o u s
n i t r o c y c l o a l k a n e s h a v e b e e n d e t e r m i n e d f o r h y d r o x i d e i o n i n 50% by
volume 1 , 2 - d i m e t l i o x y e t h a n e - w a t e r , i t was o f i n t e r e s t to d e t e r m i n e
i f t h e same s e q u e n c e h o l d s f o r o t h e r b a s e s . T h u s , t h e r a t e s o f
n e u t r a l i z a t i o n o f A- t h r o u g h 8-membered n i t r o c y c l o a l k a n e s w e r e
m e a s u r e d f o r s o d i u m m e t h o x i d e i n m e t h a n o l , s o d iu m e t h o x i d e i n e t h a n o l
and so d ium e t h y l e n e g l y c o l a t e i n e t h y l e n e g l y c o l . The r e s u l t s a r c
c o m p i l e d i n T a b l e 1 0 .
The same m e t h o d a n d t e c h n i q u e s u s e d i n t h e h y d r o x i d e i o n
c a t a l y s i s s t u d i e s w e r e u s e d i n t h e s e s y s t e m s e x c e p t f o r t h e s t u d i e s
70
In e th y len e g ly c o l . In t h i s system s p e c ia l techniques were employed
which have been d escr ib ed in d e t a i l in the Experimental S e c t io n . I t
was e s s e n t i a l to use la r g e ex ce sses o f n i t r o compound and very sm all
co n cen tra t io n s o f base . For these reason s , s tr in g en t precautions
were taken to exclude carbon d iox id e and oxygen, although i t was not
p o s i t i v e l y demonstrated that an in er t atmosphere was req u ired , p a r t ic
u la r ly i f the k in e t i c s o lu t io n s were used immediately a f t e r preparation
as in the hydroxide ion n e u tr a l iz a t io n s tu d ie s . I t i s e s p e c ia l ly
important to note that a mole r a t io o f about 200/1 i s required to
obta in complete r e a c t io n . Below th is r a t io k in e t ic p lo t s curve s i g
n i f i c a n t l y and the ra te con stan ts are low as i s dram atica lly shown in
Table 3 3 . These data emphasize the problem o f completeness of rea c t io n
as considered p rev io u s ly in d isc u ss io n of the extent o f n e u tr a l iz a t io n
of n itro cy c lo a lk a n es by hydroxide ion in aqueous media.
The r e l a t iv e r a te s of rea c t io n of homologous n itro cy c lo a lk a n es
w ith a lk oxid e b ases are (Table 12): 4 > > 5 > 7 > 8 > 6 , the same
sequence as w ith hydroxide ion . I t i s a lso observed that the ra te of
r e a c t io n i s f a s t e r w ith ethoxid e than hydroxide than methoxide than
g ly c o la t e . In g en era l , then, the r e la t iv e ra tes o f n e u tr a l iz a t io n as
a fu n c t io n o f a lkoxide r e f l e c t th e ir b a s i c i t i e s or the corresponding
s tren g th s of th e ir conjugate a c id s . A study has been made (94) o f the
(94) H. Hine and M. Hine, j . Am. Chem. S o c . , 74 , 5266 (1952) .
acid d i s s o c ia t io n con stants of a s e r ie s o f a lc o h o ls . The acid
TA15LE 12
RELATIVE RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOALKANES WITH THE SODIUM CONJUGATE EASE OF TEE SOLVENT AT 0 . 0 0 °
Compound50% 1 ,2 -
Dim et l ioxye t l ' . ane ->.-;ater
( 1 . /r.
M e t h a n o l
! . - n i n . )
E t h a n o l E t h y l e n e G l y c o l
2-N i t rop r o p ane 1 . 3 6 0 .6 3 5 1 . 3 4 1 . 7 1
N i t r o c y c l o p r o p a n e
N i t r o c y c l o b u t a n e 1 7 . 6 12.2 11.9 13.5
Ni t r o c y d o p e n t ane 5 . 1 6 3.60 5.39 5.48
N i t r o c y c l o b e x a n e 1 . 0 0 1.00 1 . 0 0 1.00
K i t ro cy c l o h ep t ane 2.98 2.59 3.23 3.90
N i t r o c y c l o o c t a n e 2.32 1 . 9 7 2.38 2 . 0 1
4 > \ 5 > 7 > 8 : 6
72
s t r e n g t h s r e l a t i v e t o t h e i s o p r o p y l a l c o h o l a r e : e t h a n o l , 0 . 9 5 ;
w a t e r , 1 . 2 0 ; m e t h a n o l , 4 . 0 ; e t h y l e n e g l y c o l , 4 3 . T h es e a r c d e t e r m i n e d
a c c o r d i n g t o E q u a t i o n 2 2 :
Kg = [ A " ] / [ H A ] [ i - P t o “ ] (22)
w h e r e HA r e p r e s e n t s an a l c o h o l , A t h e c o n j u g a t e , b a s e and ^ - P r o i s
t h e i s o p r o p o x i d e a n i o n . The i o n i z a t i o n c o n s t a n t f o r i s o p r o p y l a l c o h o l
i s d e f i n e d by t h i s e q u a t i o n t o b e 0 . 0 7 6 .
2 - N i t r o p r o p a n e was s t u d i e d t o examine t h e e f f e c t o f s t r u c t u r e
o f t h e b a s e and s o l v e n t on a r e p r e s e n t a t i v e a c y c l i c n i t r o compound.
I t i s o b s e r v e d ( T a b l e 12) t h a t t h e r a t i o o f t h e r a t e c o n s t a n t f o r
n e u t r a l i z a t i o n o f 2 - n i t r o p r o p a n e t o n i t r o c y c l o h e x a n e i s r e l a t i v e l y
c o n s t a n t a s a f u n c t i o n o f b a s e e x c e p t f o r m e t h o x i d e . The r a t i o f o r
n i t r o c y c l o b u t a n e v e r s u s n i t r o c y c l o h e x a n e i s g r e a t e r i n p a r t i a l l y
a q u e o u s medium and a b o u t t h e same f o r e a c h o f t h e a l c o h o l i c m e d i a .
The d a t a a l s o show t h a t t h e r a t i o o f r e l a t i v e r a t e s f o r t h e o t h e r
c y c l i c n i t r o compounds v e r s u s t h e 6-m embered r i n g d e r i v a t i v e v a r i e s
w i t h b a s e i n much t h e same m a n n e r . T h i s i s d e m o n s t r a t e d g r a p h i c a l l y
i n F i g u r e 1 w h ic h i s a p l o t o f t h e l o g o f t h e r a t e c o n s t a n t f o r n i t r o
c y c l o h e x a n e a s a f u n c t i o n o f s o l v e n t v e r s u s t h e l o g o f t h e r a t e c o n
s t a n t f o r e a ch o f t h e o t h e r n i t r o compounds i n t h e v a r i o u s m e d i a .
The s l o p e o f a p l o t o f t h e l o g o f t h e s e c o n d - o r d e r r a t e c o n s t a n t f o r
n e u t r a l i z a t i o n o f n i t r o c y c l o h e x a n e a g a i n s t t h e l o g o f t h e s e c o n d - o r d e r
r a t e c o n s t a n t f o r n e u t r a l i z a t i o n o f n i t r o c y c l o h e x a n e i s o n e . The
f a c t t h a t t h e s l o p e s o f e a c h o f t h e l i n e s f o r e a c h compound i s n e a r l y
. 5 0 0
Efhono
.0005 0 - 5 0 1, 2 - Dimeîhoxy-
e t h a n e - W a î e r *- /(D
2 - N i c r o p r o p a n e
Ni t r o c y c l o o c t a n e
5 0 0 N i t r o c y c l o h c p t a n e
N i t r o c y c l o p e n t a n eMet hano
N i t r o c y c l o b u t a n eEthyl ene Glycol
0.0000 . 5 0 0 (.000 1.500 2.000 2 . 5 0 0
Log k
F i g u r e 1 . w
74
one a n d , t h a t t h e a v e r a g e s l o p e o f a l l compounds i s one , s u g g e s t s
t h a t t h e s t e r i c and s o l v a t i o n r e q u i r e m e n t s f o r n e u t r a l i z a t i o n a r e t h e
same i n e a c h s y s t e m . I t i s o f n o t e t h a t a p l o t o f t h e l o g o f t h e
a c i d d i s s o c i a t i o n c o n s t a n t f o r e t h a n o l , w a t e r and m e t h a n o l v e r s u s t h e
l o g o f t h e s e c o n d - o r d e r r a t e c o n s t a n t f o r n e u t r a l i z a t i o n f o r a
p a r t i c u l a r m o l e c u l e ( F i g u r e s 2 and 3) l i e on a f a i r l y good s t r a i g h t
l i n e . The f a c t t h a t t h e r e s u l t s f o r e t h y l e n e g l y c o l a t e - e t h y l e n c
g l y c o l d o es n o t l i e on t h e l i n e i s p r o b a b l y du e t o i n t e r n a l h y d r o g e n -
b o n d i n g i n t h e g l y c o l a t e a n i o n . S a t i s f a c t o r y f r e e - e n e r g y c o r r e l a t i o n
a l s o s u g g e s t s t h a t t h e r e a r e s i m i l a r i t i e s b e t w e e n t h e t r a n s i t i o n
s t a t e s f o r n e u t r a l i z a t i o n i n t h e v a r i o u s b a s i c m e d i a .
The r a t e o f n e u t r a l i z a t i o n o f n i t r o c y c l o o c t a n e by i s o p r o p o x i d e
i o n i n i s o p r o p y l a l c o h o l was found t o be i m m e a s u r a b l y f a s t . F o r t h i s
r e a s o n , t h e s t u d i e s w e r e n o t c o n t i n u e d . B as ed on t h e d a t a o b t a i n e d
and t h e r e l a t i v e a c i d i t i e s o f t h e a l c o h o l s i n v e s t i g a t e d , t h i s r e s u l t
i s e x p e c t e d .
I n c o n t r a s t t o n i t r o c y c l o b u t a n e , n i t r o c y c l o p r o p a n e d o e s n o t
d i s s o l v e i n a q u e o u s s o d i u m h y d r o x i d e (95) an d t h e r e i s no c o n d u c t i v i t y
(95 ) H. B. Hass a n d H. S h e c h t e r , J . Am. Chem. S o c . , 7 5 , 1382 ( 1 9 5 3 ) .
ch a n g e upon a d d i t i o n o f n i t r o c y c l o p r o p a n e t o a s o l u t i o n o f so d iu m
h y d r o x i d e i n 50% by v o lu m e 1 , 4 - d i o x a n e - w a t e r . I - s t r a i n t h e o r y w o u l d
p r e d i c t t h a t c o n v e r s i o n o f t e t r a h e d r a l t o t r i g o n a l c a r b o n i n t h i s
2 .500P EfOH
Log
2.000
1.500Ethyleneglycol
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1.000 0.000 0 .5 0 0 1.000 Log Ke
.500 2.000F igure 2.
Ui
1.500
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.000
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0 .5 0 0o MeOH
0.000 0 .5 0 0 1.000 Log Ke
0.000 .500 2.000Figure 3. ON
77
3-membered r i n g d e r i v a t i v e would be v e r y d i f f i c u l t b e c a u s e o f t h e
i n c r e a s e d bond a n g l e d e f o r m a t i o n s t r a i n i n a d e l o c a l i z e d t r a n s i t i o n
s t a t e . N i t r o c y c l o b u t a n e n e u t r a l i z e s much more r a p i d l y t h a n I - s t r a i n
t h e o r y p r e d i c t s h o w e v e r , due t o o t h e r f a c t o r s i n t h e s y s t e m a s
p r e v i o u s l y d i s c u s s e d . I t may be t h a t t h e r a t e o f t h e f o r w a r d
r e a c t i o n f o r n i t r o c y c l o p r o p a n e i s v e r y f a s t f o r s i m i l a r r e a s o n s b u t
t h e r a t e o f t h e r e v e r s e r e a c t i o n i s much f a s t e r ( E q u a t i o n 23) a n d ,
t h u s , no n e t c h a n g e i s o b s e r v e d by t h e t e c h n i q u e s u s e d .
H /H fast H _+ B V - - - - - : ) c = NO + BH ( 2 3 )
B_C N0_ f a s t e r
D e u te r i u m e x c h a n g e i n t o t r a n s - 2 - e t h y l n i t r o c y c l o p r o p a n e ( 9 6 ) ,
(9 6 ) Sample p r e p a r e d i n t h i s l a b o r a t o r y by J . A s u n s k i s ; J . A s u n s k i s and H. S h e c h t e r , J . Org . Chem . , 3 3 , 1164 ( 1 9 6 2 ) .
was s t u d i e d i n d i m e t h y l f o r m a m i d e - d e u t e r i u m o x i d e c o n t a i n i n g t r i -
e t h y l a m i n e . N u c l e a r m a g n e t i c r e s o n a n c e s p e c t r a o f t h i s s y s t e m w e r e
t a k e n p e r i o d i c a l l y o v e r a 2 week p e r i o d . The r e l a t i v e i n t e n s i t i e s
o f t h e a c i d i c p r o t o n o f t h e 3-membered r i n g t o t h e c a r b o n y l p r o t o n
o f d i m e t h y l f o r r n a m i d e d i d n o t c h a n g e n o r d i d t h e a r e a u n d e r t h e
m e t h i n e p r o t o n c h a n g e w i t h i n e x p e r i m e n t a l e r r o r d u r i n g t h i s t i m e .
I n c o n t r a s t , 2 - n i t r o p r o p a n e u n d e r t h e same c o n d i t i o n s e x c h a n g e d i t s
a c i d i c p r o t i u m f o r d e u t e r i u m (>90%) w i t h i n 40 m i n u t e s . T h u s , t h e
r e l a t i v e r a t e s o f b a s e - c a t a l y z e d e x c h a n g e a r e : 2 - n i t r o p r o p a n e > >
78
t r a n s - e t i i y l n i t r o c y c l o p r o p a n e . The d i f f e r e n c e i n r e l a t i v e r a t e s o f
n e u t r a l i z a t i o n i s a t t r i b u t e d t o t h e c h a r a c t e r o f t h e c y c l o p r o p a n e
r i n g and n o t t o s t e r i c h i n d r a n c e i n t r a n s - 2 - e t h y I n i t r o c y d o p r o p a n e
i n w h i c h t h e p o s s i b l e r e m o v a b l e p r o t o n and e t h y l g ro u p a r e o f c i s -
s t e r c o c h e m i s t r y . F o r e x a m p l e , 4 - n i t r o h e p t a n e i s n e u t r a l i z e d on ly
11 t i m e s s l o w e r t h a n 2 - n i t r o p r o p a n e w i t h h y d r o x i d e i o n (24) . A
p s e u d o - f i r s t o r d e r r a t e c o n s t a n t f o r d e u t e r i u m e x c h a n g e o f 2 - n i t r o
p r o p a n e was d e t e r m i n e d by i n t e g r a t i n g t h e a r e a s u n d e r t h e a c i d i c p r o
t o n p e a k i n t h e Ilî-K s p e c t r u m a s a f u n c t i o n o f t i m e . T h i s v a l u e i s
a p p r o x i m a t e l y 1 . 2 X 10 ^ min . ^ ( T a b le ; F i g u r e ) .
The f a c t t h a t t r a n s - 2 - e t h y I n i t r o c y c l o p r o p a n e n e u t r a l i z e s
much s l o w e r t h a n n i t r o c y c l o b u t a n e ( o r 2 - n i t r o p r o p a n e ) m us t mean t h a t
t h e f e a t u r e s wl i ich c o n t r i b u t e t o t h e v e r y r a p i d r a t e o f p r o t o n
a b s t r a c t i o n f r om n i t r o c y c l o b u t a n e a r e n o t c o n t r o l l i n g i n r e a c t i o n
o f n i t r o c y c l o p r o p a n e s . F a c t o r s w h ich s h o u l d a c c e l e r a t e n e u t r a l i z a t i o n
o f n i t r o c y c l o p r o p a n e s a r e ; (1 ) a n i t r o c y c l o p r o p a n e h a s i n c r e a s e d
s - c h a r a c t e r i n i t s C-H b o n d s ; (2) t h e 3-membered r i n g compound i s
r i g i d and i t s p o t e n t i a l l y r e m o v a b l e h y d r o g e n i s e x p o s e d w’h i c h s h o u l d
make t h e e n t r o p y o f r e a c t i o n f a v o r a b l e and (3) t h e r i g i d s t r u c t u r e
s h o u l d f a v o r s o l v a t i o n . E f f e c t s , h o w e v e r , w h ich l e a d t o r e s i s t a n c e
t o n e u t r a l i z a t i o n a r e : (1 ) n i t r o c y c l o p r o p a n e s do n o t h a v e maj o r
a n g l e o r t o r s i o n a l s t r a i n s i n t h e g ro u n d s t a t e w h ich a r e r e l i e v e d
i n t r a n s i t i o n , and (2) t h e r e a r e d i s a d v a n t a g e o u s s t e r i c f a c t o r s i n
t h e t r a n s i t i o n s t a t e f o r n i t r o c y c l o p r o p a n e f o r a l l o w i n g d e l o c a l i z a t i o n
79
t h r o u g h t h e n i t r o g r o u p o r f o r a p p r o p r i a t e p - g e o m e t r y . I f d e l o c a l
i z a t i o n i n v o l v i n g t h e n i t r o g ro u p i s t h e m o s t s i g n i f i c a n t f e a t u r e
o f n e u t r a l i z a t i o n , i t . m u s t be c o n c l u d e d t h a t a n g l e s t r a i n i n t h e
t r a n s i t i o n s t a t e f o r n i t r o c y c l o p r o p a n e p r e v e n t s m a j o r d e l o c a l i z a t i o n
a n d t h a t t h e t r a n s i t i o n s t a t e f o r n i t r o c y c l o b u t a n e i s much more
d e l o c a i i z c d t h a n t h a t f o r n i t r o c y c l o p r o p a n e . On t h i s b a s i s i t i s
e v i d e n t t h a t s m a l l d i f f e r e n c e s i n s t r u c t u r e o f t h e s e t r a n s i t i o n
s t a t e s a c t u a l l y l e a d t o l a r g e d i f f e r e n c e s i n t h e i r d e l o c a l i z a t i o n
i n t e r a c t i o n s . I f on t h e o t h e r h a n d , p - c h a r a c t e r w i t h 3 bonds a t
a p p r o x i m a t e l y 90° and t h e d e v e l o p i n g e l e c t r o n p a i r i n an s - o r b i t a l
i s t h e s i g n i f i c a n t f e a t u r e o f t h e t r a n s i t i o n s t a t e f o r n i t r o c y c l o
b u t a n e , t h e 3-membered r i n g n i t r o compound c a n n o t a c h i e v e t h i s
g e o m e t r y s i n c e i t s C-C-C a n g l e s a r e h e l d a t a p p r o x i m a t e l y 6 0 ° . In
t r a n s i t i o n , t h e r e f o r e , n i t r o c y c l o p r o p a n e m u s t r e h y b r i d i z e i n i t s
2t r a n s i t i o n s t a t e t o a s s u m e e i t h e r sp o r p - g e o m e t r y an d t h i s i s
s t e r i c a l l y r e s t r i c t e d .
I t h a s b e e n r e p o r t e d (78) t h a t t h e r e l a t i v e o r d e r w i t h r e s p e c t
t o r i n g s i z e f o r b a s e - c a t a l y z e d d e u t é r a t i o n o f c y c l o a l k y l p h e n y l
k e t o n e s i n d e u t e r i u m o x i d e - d i m e t h y l f ormamide i s : 3 > > 4 > 5 > 6 > 7 .
T h e s e r e s u l t s a r e e x p l a i n e d on t h e b a s i s t h a t t h e s - c h a r a c t e r o f t h e
m e t h i n e C-H bond i n c r e a s e s w i t h d e c r e a s i n g r i n g s i z e o f t h e c y c l o
a l k y l g ro u p ( 7 8 ) . T h es e r e s u l t s c e r t a i n l y do n o t a g r e e w i t h t h o s e
o f t h e p r e s e n t i n v e s t i g a t i o n . To examine f u r t h e r t h e r e a c t i v i t y o f
m e t h i n e h y d r o g e n o f c y c l o p r o p a n e r i n g s , t h e r a t e o f e x c h a n g e o f
80
d e u t e r i u m i n t o d i c y c l o p r o p y l k e t o n e was s t u d i e d i n d e u t e r i u m o x i d e -
d i m e t h y l f o r m a m i d e c o n t a i n i n g d e u t e r o x i d e i o n ( a p p r o x i m a t e l y 0 . 6 ^ ) .
The r e a c t i o n was f o l l o w e d by NÎIR t e c h n i q u e s i n t h e same m an n e r a s
f o r t r a n s - 2 - e t h y l - n i t r o c y c l o p r o p a n e . A f t e r 5 d a y s a t room t e m p e r
a t u r e , no d e u t e r i u m c o u l d be d e t e c t e d i n t h e m e t h i n e p o s i t i o n . The
e x p e r i m e n t was t h e n r e p e a t e d u s i n g p o t a s s i u m t - b u t o x i d e ( 0 . 2 1 i n
t - b u t a n o l - d ^ . NÎIR s p e c t r a of t h e s y s t e m w e r e o b s e r v e d f o r 20 d a y s
a t room t e m p e r a t u r e . No i n c o r p o r a t i o n o f d e u t e r i u m c o u l d b e d e t e c t e d .
D ess y a 2 . ( 9 7 ) f o u n d t h a t d e u t e r o x i d e i o n r e a d i l y c a t a l y z e s
(97) R. E. D e s s y , Y. Okuzumi, an d A. Chen, J . Am. Chem. S o c . , W , 2899 ( 1 9 6 2 ) .
-2 -1e x c h a n g e i n t o i s o p r o p y l p h e n y l k e t o n e ( k ^ = 1 . 0 x 10 s e c . a t 4 0 ° ) .
I f d i c y c l o p r o p y l k e t o n e exchan ged a t t h e same r a t e u n d e r t h e e x p e r i
m e n t a l c o n d i t i o n s o f t h i s i n v e s t i g a t i o n , t h e n t h e k e t o n e s h o u l d h a v e
b e e n 100% d e u t e r a t e d i n 20 d a y s . D e s s y ( 7 8 ) a l s o r e p o r t s t h a t c y c l o -
p r o p y l p h e n y l k e t o n e i s d e u t e r a t e d c a t a l y z e d by t r i e t h y l a r a i n e
-6 -1(kj^ = 1 . 0 X 10 s e c . a t 4 0 ° ) . I f d i c y c l o p r o p y l k e t o n e e x c h a n g e d
a t t h e same r a t e u n d e r t h e e x p e r i m e n t a l c o n d i t i o n s o f t h i s i n v e s t i
g a t i o n , t h e n i t s h o u l d h a v e b ee n 82.5% e x c h a n g e d i n 20 d a y s .
T h es e r e s u l t s h a v e i n i t i a t e d r e i n v e s t i g a t i o n o f b a s e - c a t a l y z e d
d e u t e r i u m e x c h a n g e o f v a r i o u s i s o p r o p y l a n d c y c l o p r o p y l k e t o n e s ( 7 8 )
i n t h i s l a b o r a t o r y . I t i s found (98) t h a t d i c y c l o p r o p y l k e t o n e d o e s
(98) K. C. K a u f fm an , The Ohio S t a t e U n i v e r s i t y .
81
n o t d e u t e r a t e i n sod ium d e u t c r o x i d c - d e u t e r i u m o x i d e - d i r . i e t h y l f o r m a m i d e
i n 30 h o u r s a t 60° w h e r e a s d i i s o p r o p y l k e t o n e i s 40% monoexchanged
i n 20 h o u r s u n d e r t h e s e c o n d i t i o n s . C y c l o p r o p y l p h e n y l k e t o n e i n
s o d iu m d e u L e r o x i d e - d e u t e r i u m o x i d e - d i m e t h y l f o r m a m i d e r e s i s t s d e u t é r
a t i o n i n 14 h o u r s a t 6 0 ° ; u n d e r i d e n t i c a l c o n d i t i o n s i s o p r o p y l p h e n y l
k e t o n e i s 55-58% e x c h a n g e d i n 1 7 . 5 h o u r s . T h e s e r e s u l t s i n d i c a t e
t h a t t h e p r e v i o u s work w i t h c y c l o p r o p y l p h e n y l k e t o n e i s i n e r r o r and
t h a t s t e r i c i n h i b i t i o n o f d e l o c a l i z a t i o n a l s o r e p r e s s e s b a s e - c a t a l y z e d
e n o l i z a t i o n o f c y c l o p r o p y l k e t o n e s . S i m i l a r r e s u l t s h a v e b e e n
o b t a i n e d by Rappe and S achs (99) i n t h a t m e t h y l c y c l o p r o p y l k e t o n e
(99 ) P r i v a t e c o m m u n i c a t i o n f r om P r o f e s s o r C. R a p p e , U n i v e r s i t y U p p s a l a , U p p s a l a , Sweden.
and c y c l o p r o p y l p h e n y l k e t o n e r e s i s t d e u t e r o x i d e - c a t a l y z e d d e u t e r i u m
e x c h a n g e i n d e u t e r i u m o x i d e - d i o x a n e . I t h a s a l s o b e e n r e p o r t e d (100)
( 10 0) J . G. A t k i n s o n , J . J . C s a k v a r y , G. T. H e r b e r t and R. S . S t u a r t , J . Am. Chem. S o c . , 90 , 498 ( 1 9 6 8 ) .
t h a t s a l t s o f c y c l o p r o p a n e c a r b o x y l i c a c i d do n o t u n d e r g o d e u t e r i u m
e x c h a n g e i n d e u t e r i u m o x i d e u n d e r c o n d i t i o n s i n w h ich d e u t e r i u m
i n c o r p o r a t i o n i n t o t h e h i g h e r h o m o lo g s i s e x t e n s i v e .
E a r l i e r i t h a s b e e n r e p o r t e d (83) t h a t 2 , 2 - d i p h e n y l c y c l o p r o p y l
c y a n i d e i s r a c e m i z e d r a p i d l y by l i t h i u m d i i s o p r o p y l a m i d e i n e t h e r
82
a t - 8 0 ° and t h a t i t u n d e r g o e s b a s e - c a t a l y z e d d e u t e r i u m e x c h a n g e 31
t i m e s f a s t e r t h a n d o es 2 - m e t h y l - 3 , 3 - d i p h e n y l p r o p i o n i t r i l e u n d e r
i d e n t i c a l c o n d i t i o n s . I n l i g h t o f p r e s e n t w ork o f t h i s l a b o r a t o r y ,
t h e s e r e s u l t s a r e n o t u n d e r s t o o d .
S i n c e n e u t r a l i z a t i o n o f c y c l i c n i t r o compounds w i t h h y d r o x i d e
a n d a l k o x i d e b a s e s show e s s e n t i a l l y t h e same p a t t e r n , i t was o f
i n t e r e s t t o d e t e r m i n e i f w e a k e r , more h i n d e r e d b a s e s w i l l a l t e r t h e
r e l a t i v e r e a c t i v i t i e s o f t h e n i t r o c y c l o a l k a n e s . A s t u d y was t h u s
made o f t h e r a t e s o f n e u t r a l i z a t i o n o f t h e 4 - t l i r ough 8-membered
n i t r o c y c l o a l k a n e s by e x c e s s t r i c t h y l a r . i i n e ( 5 0 / 1 ) i n 50% by volume
1 , 2 - d i m e t l i o x y e t h a n e - w a t c r u n d e r p s e u d o - f i r s t o r d e r c o n d i t i o n s u s i n g
t e c h n i q u e s s i m i l a r t o t h o s e em ployed f o r h y d r o x i d e i o n c a t a l y s i s .
The p r o c e d u r e i s d i s c u s s e d i n d e t a i l i n t h e E x p e r i m e n t a l S e c t i o n .
The s e c o n d - o r d e r k i n e t i c s o f n e u t r a l i z a t i o n o f n i t r o e t h a n e by
a m i n e s ( 3 4 , 3 5 , 3 7 ) and p y r i d i n e s ( 3 5 , 1 0 1 ) h a v e b e e n s t u d i e d c o n d u c t o -
( 1 01) E. S . Lew is and L. H. F u n d e r b u r k , J . Am. Chem. S o c . , 8 9 , 2322 ( 1 9 6 7 ) .
m e t r i c a l l y . W i th ammonia and a l k y l a m i n e s ( 3 4 , 3 6 , 3 7 ) n e u t r a l i z a t i o n
i s c o m p l i c a t e d by r e v e r s e r e a c t i o n o f t h e ammonium and t h e a l k y l -
ammoniura i o n s w i t h n i t r o n a t e i o n . The r e v e r s e r e a c t i o n s may, how
e v e r , b e n e g l e c t e d f o r ammonia or m e t h y l a m i n e s i f t h e m e a s u r e m e n t s
a r e n o t c a r r i e d o u t t o o f a r (34) (10-25% f o r ammonia; 20-40% f o r
t r i m e t h y l a m i n e an d 25-75% f o r m e t h y l a m i n e an d d i m e t h y l a m i n e ) . The
83
s y s t e m i s f u r t h e r c o m p l i c a t e d by s i m u l t a n e o u s r e a c t i o n w i t h h y d r o x i d e
i o n ; t h e c o r r e c t i o n t e r m (102) f o r n e u t r a l i z a t i o n by h y d r o x i d e i o n i s
(102) F . V. W i l l i a m s , Ph .D. d i s s e r t a t i o n , N o r t h w e s t e r n U n i v e r s i t y , 1953 .
s m a l l . T h u s , a r e l a t i o n may be d e r i v e d to s t u d y s e c o n d - o r d e r
n e u t r a l i z a t i o n i n t e r m s o f t h e r a t e c o n s t a n t s f o r amine and h y d r o x i d e
i o n c a t a l y s i s and t h e i o n i z a t i o n c o n s t a n t o f t h e am in e . W ith
p y r i d i n e b a s e s ( 3 5 ) , t h e r e a c t i o n may b e d r i v e n t o c o m p l e t i o n by
a d d i t i o n o f i o d i n e .
I n t h e p r e s e n t i n v e s t i g a t i o n i t was f e l t t h a t r e v e r s a l o f
n e u t r a l i z a t i o n wou ld be m i n i m i z e d by u s i n g t r i e t h y l a m i n e i n l a r g e
e x c e s s . A l s o , s t u d y o f p s e u d o - f i r s t o r d e r k i n e t i c s i s a d v a n t a g e o u s
b e c a u s e o f t h e m a t h e m a t i c a l s i m p l i c i t y i n p r o c e s s i n g t h e d a t a and
b e c a u s e o f t h e s a t i s f a c t o r y t e c h n i q u e s d e v e l o p e d p r e v i o u s l y i n t h e
n e u t r a l i z a t i o n s t u d i e s u s i n g h y d r o x i d e and a l k o x i d e b a s e s .
To a t t a i n s o l u t i o n o f n i t r o c y c l o a l k a n e s o f h i g h e r m o l e c u l a r
w e i g h t a c o s o l v e n t w i t h w a t e r was n e c e s s a r y . 1 , 2 - U i m e t h o x y e t h a n e
was u s e d b e c a u s e o f i t s e a s e o f p u r i f i c a t i o n and t o a l l o w c o m p a r i s o n
o f r e s u l t s o f n e u t r a l i z a t i o n by t r i e t h y l a m i n e w i t h t h o s e by h y d r o x i d e
i o n d i s c u s s e d p r e v i o u s l y . K i n e t i c s o l u t i o n s w e re p r e p a r e d w i t h
p u r i f i e d s o l v e n t s a s d e s c r i b e d i n d e t a i l i n t h e E x p e r i m e n t a l S e c t i o n .
The r e a c t i o n r a t e s w e r e d e t e r m i n e d upon i n j e c t i n g m i c r o l i t e r a l i q u o t s
84
o f t h e n e a t n i t r o compound i n t o k i n e t i c s o l u t i o n s o f t r i e t h y l a m i n e i n
50% by volume 1 , 2 - d i m e t h o x y e t h a n e - w a t e r t h e r m o s t a t e d i n a c o n d u c t i v i t y
c e l l . The d e c r e a s e i n c e l l r e s i s t a n c e ( i n c r e a s e i n c o n d u c t i v i t y ) i s
f o l l o w e d w i t h t im e and t h e ch a n g e i n c o n d u c t i v i t y i s p r o p o r t i o n a l t o
t h e c o n c e n t r a t i o n o f n i t r o n a t e and t r i e t h y l a m m o n i u m i o n s . The
k i n e t i c s obey a f i r s t o r d e r r a t e e x p r e s s i o n and t h e d a t a g i v e e x c e l l e n t
s t r a i g h t l i n e s t o 75-90% c o m p l e t i o n o f r e a c t i o n . The r e s i s t a n c e c o n
t i n u e s t o d e c r e a s e , h o w e v e r , a f t e r " i n f i n i t e " t i m e b u t t h e d e c r e a s e i s
n o t more t h a n 5% o f t h e t o t a l c h a n g e . The s u b s e q u e n t ch an g e i n c o n
d u c t i v i t y i s a t t r i b u t e d t o d e c o m p o s i t i o n o f t h e n i t r o n a t e a n i o n t o
s a l t s o f o r g a n i c a c i d s and n i t r i t e i o n (91) .
TiJO q u e s t i o n s a b o u t t h i s k i n e t i c s y s t e m must be c o n s i d e r e d .
F i r s t , what c o n t r i b u t i o n t o t h e o b s e r v e d p s e u d o - f i r s t o r d e r r a t e c o n
s t a n t i s h y d r o x i d e i o n m a k i n g , and s e c o n d , a r e t h e s e r e a c t i o n s g o i n g
t o c o m p l e t i o n .
E x c e l l e n t s t r a i g h t l i n e s d e r i v e d f r o m t h e k i n e t i c d a t a s u g g e s t
t h a t t h e c o n t r i b u t i o n t o t h e r a t e c o n s t a n t b y r e a c t i o n o f h y d r o x i d e
i o n w i t h t h e n i t r o compounds i s e i t h e r e s s e n t i a l l y c o n s t a n t a n d / o r
n e g l i g i b l e . I t a p p e a r s t h a t t h e c o n t r i b u t i o n f r om h y d r o x i d e i o n t o
t h e o b s e r v e d p s e u d o - f i r s t o r d e r r a t e c o n s t a n t i s s m a l l b u t n o t
n e g l i g i b l e . T h i s c o n c l u s i o n i s b a s e d i n p a r t on p r e s e n t d e t e r m i n a t i o n
o f t h e e q u i l i b r i u m c o n s t a n t o f t r i e t h y l a m i n e i n 50% by volume
85
g l y m e - w a t e r t o b e 6 . 4 8 X 10" a t 20® ( 1 0 3 ) . T h u s , i n t h e k i n e t i c
(103 ) I t i s as sumed t h a t t h e i o n p r o d u c t c o n s t a n t o f w a t e r i n 50% by volume 1 , 2 - d i i n e t h o x y e t h a n e - w a t e r a t 20® i s t h e same as i n 45% by w e i g h t d i o x a n e - w a t e r a t 25° ( 1 . 8 1 X 1 0 " ^ ^ ) ; H. F r e i s e r and Q. F e r n a n d o , " I o n i c E q u i l i b r i a i n A n a l y t i c a l C h e m i s t r y " , Jo h n W i l e y and S o n s , I n c . , New York , 19 63 , p . 17 .
s y s t e m ( t r i e t h y l a m i n e , 0 . 2 1 0 M) a t 0 . 0 ° , t h e c o n c e n t r a t i o n o f
h y d r o x i d e i o n i s c a l c u l a t e d t o b e 1 . 1 6 X 10"^ M ( 1 0 4 ) . S i n c e t h e
(1 04) I t i s a s sum ed t h a t t h e i o n i z a t i o n c o n s t a n t o f t r i e t h y l a m i n e i s n o t a p p r e c i a b l y d i f f e r e n t a t 0° t h a n a t 2 0 ° ; S. G l a s s t o n e , " P h y s i c a l C h e m i s t r y " , D. Van N o s t r a n d Company, I n c . , 1 9 4 0 , p . 9 7 4 - 5 .
s e c o n d - o r d e r r a t e f o r n e u t r a l i z a t i o n o f n i t r o c y c l o b u t a n e , t h e w e a k e s t
a c i d , by h y d r o x i d e i o n a t 0° i s 143 l . / m . - m i n . , t h e p s e u d o - f i r s t
o r d e r r a t e c o n s t a n t f o r n e u t r a l i z a t i o n w i t h h y d r o x i d e i o n i n t h i s
s y s t e m i s c a l c u l a t e d t o be 1 . 6 6 X 10 ^ (k ^ = 1 , 1 6 X 1 0 " ^ x 1 4 3 ) .
The o b s e r v e d p s e u d o - f i r s t o r d e r r a t e c o n s t a n t f o r n e u t r a l i z a t i o n o f
n i t r o c y c l o b u t a n e i s a p p r o x i m a t e l y 0 . 3 8 9 m i n . T h u s , n e u t r a l i z a t i o n
b y h y d r o x i d e i o n c o n t r i b u t e s a b o u t 4.3% t o t h e o b s e r v e d r a t e co n
s t a n t . I t may a l s o b e shown t h a t t h e c o n c e n t r a t i o n o f h y d r o x i d e i o n
d e c r e a s e s a p p r o x i m a t e l y 20% d u r i n g t h e c o u r s e o f t h e r e a c t i o n (1 05 )
(1 0 5 ) H. F r e i s e r and Q. F e r n a n d o , p p . 1 1 5 - 7 .
a n d t h u s p l a y s a s m a l l e r r o l e a s t h e r e a c t i o n p r o g r e s s e s .
8 6
The i o n i z a t i o n c o n s t a n t of t r i e t h y l a m i n e was p r e s e n t l y d e t e r
m in ed by a metho d s i m i l a r t o t h a t r e c e n t l y d e v e l o p e d t o d e t e r m i n e t h e
i o n i z a t i o n c o n s t a n t s o f weak a c i d s i n p u r e d i m e t h y l s u l f o x i d e . These
t e c h n i q u e s a r e d i s c u s s e d i n t h e E x p e r i m e n t a l S e c t i o n . The i o n i z a t i o n
c o n s t a n t o f t r i e t h y l a m i n e h a s been d e t e r m i n e d p r e v i o u s l y i n mixed
s o l v e n t s and i n m e t h a n o l and e t h a n o l . Some o f t h e l i t e r a t u r e v a l u e s
a r e : 5 . 6 9 X 10“ ^ ( w a t e r , 2 5 ° ) ; 4 . 2 3 X 10~^ ( m e t h a n o l , 2 5 ° ) ; 5 . 6 7 X
1 0 " ^ ( e t h a n o l , 25° ) ( 1 0 6 ) ; 5 . 6 2 X l O ' ^ ^ (70% e t h a n o l , 25° ) ( 1 0 7 ) ;
- 61 . 0 X 10 ( m e t h a n o l , room t e m p e r a t u r e ) (1 0 8 ) .
( 1 06) C. L i and T. D. S t e w a r t , J . Am. Chem. S o c . , 5_9, 2596( 1 9 3 7 ) .
(1 0 7 ) E. T. B o r r o w s , M. C. H a r g r e a v e s , J . E. P a g e , J . C. S. R e s u g g a n and F . A. R o b i n s o n , J . Chem. S o c . , 201 ( 1 9 4 7 ) .
(1 0 8 ) J . R. S c h a c f g e n , M. S . Newman and F . H. Verhoek, J . Am. Chem. S o c . , 66 , 1847 ( 1 9 4 4 ) .
I f t h e i o n i z a t i o n c o n s t a n t o f t r i e t h y l a m i n e i s l e s s t h a n t h a t
m e a s u r e d i n t h i s s t u d y , t h e n h y d r o x i d e i o n c a t a l y s i s w i l l be ev e n
m ore i n s i g n i f i c a n t . Under su c h c o n d i t i o n s , h o w e v e r , h y d r o l y s i s , t h e
r e v e r s e r e a c t i o n , may c o n t r i b u t e s i g n i f i c a n t l y t o t h e o b s e r v e d r a t e .
T h u s , t h e r a t e c o n s t a n t m ea s u r ed would be s m a l l e r t h a n t h e a c t u a l
r a t e c o n s t a n t .
An e s t i m a t e o f t h e c o m p l e t e n e s s o f t h e s e r e a c t i o n s may be made
f r o m a k n o w led g e o f t h e v a r i o u s c o n s t a n t s o f t h e e q u i l i b r i u m
e x p r e s s i o n :
K = K K, /K eq N o w
87
where i s t h e i o n i z a t i o n c o n s t a n t f o r n i t r o c y c l o b u t a n e ( 2 . 9 6 X
-1 010 i n 33.3% by w e i g h t m e t h a n o l - w a t e r ) , i s t h e i o n i z a t i o n c o n -
-8s t a n t f o r t r i e t h y l a m i n e ( 6 . 4 8 X 10 ) and i s t h e i o n p r o d u c t c o n -
- 1 7s t a n t f o r w a t e r ( 1 . 8 1 X 10 ) ( 1 0 9 ) . T h u s , K = 1 . 0 6 . U n d e r t h eeq
(109) T h i s v a l u e i s e s t i m a t e d by a s i m p l e c a l c u l a t i o n f r om t h e v a l u e g i v e n i n r e f e r e n c e (103) i n a s i m i l a r s o l v e n t s y s t e m and c o r r e c t e d f o r t h e t e m p e r a t u r e d e p e n d e n c e o f t h e i o n p r o d u c t c o n s t a n t o f w a t e r a s g i v e n i n r e f e r e n c e ( 1 0 4 ) .
k i n e t i c c o n d i t i o n s ( t r i e t h y l a m i n e 0 . 2 1 0 M, n i t r o c y c l o b u t a n e
(0 . 0 0 2 7 0 M), t h e c o n c e n t r a t i o n of t h e n i t r o n a t e a n i o n a t e q u i l i b r i u m
i s c a l c u l a t e d t o be 0 . 0 0 2 5 M and t h e r e f o r e , t h e r e a c t i o n i s 93%
c o m p l e t e . However , i t s h o u l d be n o t e d t h a t t h e i o n i z a t i o n c o n s t a n t
f o r n i t r o c y c l o b u t a n e was m eas u r ed i n 33.3% by w e i g h t m e t h a n o l - w a t e r
a t 25® ( . 2 1 9 mole f r a c t i o n m e t h a n o l ) and t h e k i n e t i c s a r e b e i n g
c a r r i e d o u t i n 50% by vo lum e 1 , 2 - d i m e t h o x y e t h a n e - w a t e r a t 0° ( . 1 4 7
mole f r a c t i o n 1 , 2 - d i m e t h o x y e t h a n e ) . T h u s , t h e i o n i z a t i o n c o n s t a n t
f o r t h e 4-membered c y c l i c n i t r o compound i s e x p e c t e d t o b e l e s s i n
- n - 1 0t h e k i n e t i c s o l v e n t . I f i t w ere 2 . 9 6 X 10 i n s t e a d o f 2 . 9 6 X 10 ,
t h e n e u t r a l i z a t i o n r e a c t i o n i s c a l c u l a t e d t o be 89% c o m p l e t e . I f t h e
-12i o n i z a t i o n c o n s t a n t o f n i t r o c y c l o b u t a n e i s 2 .96 X 10 , t h e r e a c t i o n
i s o n l y 56% c o m p l e t e .
T hese c a l c u l a t i o n s a r e b a s e d on t h e e s t i m a t e d i o n p r o d u c t
c o n s t a n t o f w a t e r a t 0 ° . At h i g h e r t e m p e r a t u r e s , w i l l b e g r e a t e r
and t h i s w i l l mean t h a t n e u t r a l i z a t i o n wou ld be l e s s c o m p l e t e . A l s o ,
8 8
a t h i g h e r t e m p e r a t u r e s , d e c o m p o s i t i o n o f t h e c y c l o a l k a n c n i t r o n a t e
s a l t s i s e x p e c t e d t o b e g r e a t e r . The o r g a n i c a c i d s formed i n
d e c o m p o s i t i o n w i l l i n c r e a s e h y d r o l y s i s . T h u s , t h e r a t e c o n s t a n t s
f o r n e u t r a l i z a t i o n o f n i t r o c y c l o a l k a n e s by a m i n e s d e t e r m i n e d a t 0°
a r e e x p e c t e d t o be more a c c u r a t e t h a n t h o s e a t h i g h e r t e m p e r a t u r e s .
I t s h o u l d be n o t e d , h o w e v e r , t h a t t h e more s i g n i f i c a n t h y d r o l y s i s
becom es t h e l o w e r w i l l b e t h e measured r a t e c o n s t a n t f o r n e u t r a l
i z a t i o n o f a n i t r o compou nd .
The p s e u d o - f i r s t o r d e r n e u t r a l i z a t i o n o f 2 - n i t r o p r o p a n e w i t h
t r i e t h y l a m i n e i n 50% by volume 1 , 2 - d i m e t h o x y e t h a n e - w a t e r was s t u d i e d
o v e r a r a n g e of a m i n e c o n c e n t r a t i o n s ( 0 . 2 1 0 - 0 . 0 3 4 2 M, 2 - n i t r o p r o p a n e =
0 . 0 0 2 6 8 M) . The r a t i o o f am ine to n i t r o compound r a n g e d f r o m 7 8 / 1 t o
1 2 / 1 . P l o t s o f t h e k i n e t i c d a t a a r e v e r y goo d and t h e v a l u e s f o r
4-t h e c a l c u l a t e d s e c o n d - o r d e r r a t e c o n s t a n t f r o m a l l r u n s a r e 0 . 2 9 8 -
0 . 0 1 5 ( - 5.0%) a t 2 0 ° . T h e s e d a t a s u b s t a n t i a t e t h e c o n s i s t e n c y and
n e g l i g i b i l i t y o f t h e c o n t r i b u t i o n of h y d r o x i d e i o n t o t h e o b s e r v e d
p s e u d o - f i r s t o r d e r r a t e c o n s t a n t .
The s e c o n d - o r d e r r a t e c o n s t a n t s f o r n e u t r a l i z a t i o n o f t h e
n i t r o c y c l o a l k a n e s a n d 2 - n i t r o p r o p a n e w i t h t r i e t h y l a m i n e i n 50% by
v o lu m e 1 , 2 - d i m e t h o x y e t h a n e - w a t e r d e t e r m i n e d i n t h i s s t u d y a r e c o m p i l e d
i n T a b l e 13. The b a s e - r e a c t a n t r a t i o s w e r e i n t h e o r d e r o f 7 8 - 4 0 / 1 .
R e p r e s e n t a t i v e d a t a a n d k i n e t i c p l o t s a r e i n c l u d e d i n t h e A p p e n d i x .
P l o t s o f l o g ( k ^ / T ) v e r s u s 1 / T , t o d e t e r m i n e t h e a c t i v a t i o n p a r a m e t e r s ,
a r e e x c e l l e n t s t r a i g h t l i n e s a l t h o u g h t h e v a l u e s o f a c t i v a t i o n e n t h a l p y
a n d e n t r o p y a r e u n u s u a l l y lo w .
TABLE 13
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOALKANES WITH TRIETHYLAMINE IN 50% BY VOLUME I , 2-ÜIMETH0XYETHANE-WATER
Compound k z f O " ) * k ^ ( 1 0 ° ) ^ k ( 2 0 ° ) ^2
bAll* AS*^
2 - N i t r o p r o p a n e 0 . 0 6 5 3 0 . 1 4 2 0 . 2 7 7 1 1 . 8 - 2 8 . 8
N i t r o c y c l o b u t a n e 1 . 8 3 3 . 4 8 6 . 4 1 9 . 8 8 - 3 3 . 8
N i t r o c y c l o p e n t a n e 0 . 3 2 3 0 . 6 4 1 1 . 1 9 9 . 9 3 - 3 2 . 4
N i t r o c y c l o h e x a n e 0 . 0 4 4 3 0 . 0 9 3 3 0 . 2 1 8 1 1 . 3 - 3 1 . 2
N i t r o c y c l o h e p t a n e 0 . 2 8 7 0 . 4 9 6 0 . 8 7 8 8 . 0 1 - 4 0 . 3
N i t r o c y c l o o c t a n e 0 . 1 8 8 0 . 3 6 7 0 . 6 5 8 9 . 3 8 - 3 5 . 5
4 » 5 > 7 > 8 > 6
k- 2 ( l . / m . - m i n . )
^ A U * ( k c a l . / m o l e )
^ A S * ( c a l . / m . - d e g . )
00VO
90
The r a t e s o f n e u t r a l i z a t i o n o f 2 - n i t r o p r p p a n e w e re m e a s u r e d
a s a f u n c t i o n of t e m p e r a t u r e i n 25% by v o lu m e 1 , 2 - d i m e t h o x y e t h a u e -
w a t e r . The k i n e t i c d a t a a r e v e r y good and t h e a c t i v a t i o n e n t h a l p y
( 1 3 . 5 k c a l . / m o l e ) and e n t r o p y ( - 2 0 . 8 E. U . ) a r e a l m o s t o f t h e
m a g n i t u d e o f t h a t f rom p r e v i o u s work ( 3 4 , 3 5 ) .
The d a t a stiow t h a t t h e r e l a t i v e o r d e r o f r a t e s o f n e u t r a l
i z a t i o n i s 4 > > 5 > 7 > 8 > 6 , t h e same a s w i t h h y d r o x i d e and
a l k o x i d e b a s e s . I t i s n o t e d t h a t t h e e n t h a l p i e s o f a c t i v a t i o n a r e
v e r y u n f a v o r a b l e (Ail* 8 - 1 2 k c a l . / m o l e , AS* - 2 9 t o - 4 0 E . U . ) . I t
h a s b e e n d e t e r m i n e d p r e v i o u s l y t i i a t t h e a c t i v a t i o n e n t h a l p i e s f o r
n e u t r a l i z a t i o n o f n i t r o e t h a n e w i t l i a l k y l a m i n e s and p y r i d i n e s a r e
a p p r o x i m a t e l y 15 k c a l . / m o l e (34) and 1 6 . 6 k c a l . / m o l e (35) r e s p e c t
i v e l y , and t h a t t h e y do n o t ch a n g e a p p r e c i a b l y a s e t h a n o l i s added
t o t h e s o l v e n t ( 3 5 ) . The low v a l u e s f o r t h e a c t i v a t i o n p a r a m e t e r s
ca n be t h e r e s u l t o f r a t e c o n s t a n t s b eco m in g p r o p o r t i o n a t e l y l e s s
a t 10 and 2 0 “ t h a n t h e i r a c t u a l v a l u e s i f h y d r o l y s i s o f t h e n i t r o n a t e
a n i e n s become more s i g n i f i c a n t a t h i g h e r t e m p e r a t u r e s . T h i s i s a
g e n e r a l o b s e r v a t i o n f o r c a r b o x y l i c a c i d s ( 1 1 0 ) . I t i s e x p e c t e d .
(110) S. G l a s s t o n e , " P h y s i c a l C h e m i s t r y " , D. Van N o s t r a n d Company, I n c . , 19 40 , pp . 9 7 4 - 5 .
t o o , t h a t d e c o m p o s i t i o n o f t h e n i t r o n a t e a n i o n s i n c r e a s e w i t h t e m p e r
a t u r e ( 9 1 ) . S i n c e o r g a n i c a c i d s a r e fo rmed by d e c o m p o s i t i o n , t h e y
91
w i l l i n c r e a s e t h e e x t e n t o f r e v e r s e , r e a c t i o n . I t i s known, t o o , t h a t
t h e i o n p r o d u c t c o n s t a n t o f w a t e r i n c r e a s e s w i t h t e m p e r a t u r e which
w i l l d e c r e a s e t h e e q u i l i b r i u m c o n s t a n t b e t w e e n n i t r o compound and i t s
a n i o n . F o r t h e s e r e a s o n s , t h e k i n e t i c d a t a a t 0° a r e b e l i e v e d t o be
more a c c u r a t e .
S i n c e h y d r o l y s i s o f c y c l o b u t a n e n i t r o n a t e i s e x p e c t e d t o be
more e x t e n s i v e t h a n f o r t h e o t h e r c y c l i c n i t r o n a t e s , t h e r a t e - c o n s t a n t
d e t e r m i n e d f o r n i t r o c y c l o b u t a n e s h o u l d be i n e r r o r ( l o w e r t h a n i t s
a c t u a l v a l u e ) more t h a n f o r any o f i t s h i g h e r h o m o l o g s . The f a c t
t h a t t h e r a t e c o n s t a n t d e t e r m i n e d i n t i i i s s y s t e m i s h i g h e r f o r n i t r o
c y c l o b u t a n e t h a n any o f t h e o t h e r s i s , t h u s , most s i g n i f i c a n t . T h i s
c a n mean t h a t t h e s t e r i c , s o l v a t i o n a n d / o r d e l o c a l i z a t i o n f a c t o r s
w h i c h a r e o p e r a t i v e i n n e u t r a l i z a t i o n o f t h e 4 - t h r o u g h 8-membered
n i t r o c y c l o a l k a n e s by c h a r g e d b a s e s a r e a l s o o p e r a t i v e w i t h t r i e t h y l -
2a m i n e . T h u s , i t may b e a r g u e d t h a t s p g e o m e t r y i n t l ie t r a n s i t i o n
s t a t e f o r n e u t r a l i z a t i o n w i t h t r i e t h y l a r . i i n e i s n o t s i g n i f i c a n t l y
d e v e l o p e d . S i m i l a r l y , n i t r o c y c l o b u t a n e may be p a r t i c u l a r l y w e l l
s u i t e d t o a t t a i n p - g e o m e t r y i n t r a n s i t i o n o r p e r h a p s s o l v a t i o n i s
p l a y i n g a s i g n i f i c a n t r o l e i n t h e s e p r o c e s s e s . Most p r o b a b l y , a
c o m b i n a t i o n o f a l l t h r e e f a c t o r s i s t h e m o s t a c c u r a t e p i c t u r e o f t h e
n e u t r a l i z a t i o n t r a n s i t i o n s t a t e o f n i t r o c y c l o b u t a n e .
EXPERIMENTAL
G e n e r a l P r o c e d u r e s a nd T e c h n i q u e s
Gas C h r o m a t o g r a p h i c A n a l y s i s . — Gas c h r o m a t o g r a p h i c a n a l y s e s
o f t h e k i n e t i c r e a c t a n t s w e r e c a r r i e d o u t u s i n g bo th a Flame I o n i z a
t i o n Gas C h r o m a t o g r a p h ( V a r i a n - A e r o g r a p h , H y - F i Model 600 D) and a
T h e r m a l C o n d u c t i v i t y Gas C hro m a to g ra p h (F a n d M S c i e n t i f i c , H e w l e t t -
P a c k a r d , Model 720 D u a l Column Programmed T e m p e r a t u r e ) . The f l a m e
i o n i z a t i o n a n a l y s e s w e r e e f f e c t e d on e i t h e r a 5 f t , o r a 10 f t . by
1 / 8 i n . c o p p e r column p a c k e d w i t h Carbowax 20 M (U' i lkens I n s t r u m e n t
a n d R e s e a r c h , I n c . , 20%) on Chromsorb ( V a r i a n - A e r o g r a p h , V7-AW-DMCS
6 0 / 8 0 ) . The column l e n g t h was s e l e c t e d on t h e b a s i s o f t h e r e t e n t i o n
t i m e s a n d d i f f i c u l t y o f s e p a r a t i o n o f t h e c o m p o n e n t s i n t h e m a t e r i a l .
A 10 f t . by 1 / 4 i n . c o p p e r column o f Carbowax 20 M (20%) on C h r o m s o rb
(W-AW-DMCS 6 0 / 8 0 ) was u s e d f o r t h e a n a l y s e s by t h e r m a l c o n d u c t i v i t y
m e t h o d s . T h i s same co lu m n was u s e d f o r t h e p u r i f i c a t i o n o f n i t r o
compou nd s by p r e p a r a t i v e g a s c h r o m a t o g r a p h y .
P r e c i s i o n R e c t i f i c a t i o n T e c h n i q u e s . — A l l p r e c i s i o n r e c t i f i
c a t i o n s w e re e f f e c t e d on a s p i n n i n g band co lu m n eq u ip p ed w i t h a s t a i n
l e s s s t e e l band (18 i n . ) . The h i g h e r m o l e c u l a r w e ig h t n i t r o c y c l o
a l k a n e s w e r e d i s t i l l e d a t r e d u c e d p r e s s u r e . The d i s t i l l a t i o n s w e r e
92
93
f o l l o w e d by g a s c h r o m a t o g r a p h i c a n a l y s i s o f s u c c e s s i v e , f r a c t i o n s o f
t h e m a t e r i a l . T h i s m e th o d was a b l e t o show, i n a l l c a s e s , t h e m i n i
m i z a t i o n o r r e m o v a l o f a l l s t a r t i n g m a t e r i a l s and u n i d e n t i f i e d
c o m p o n e n t s f rom a c r u d e r e a c t i o n p r o d u c t o r c o m m e r c i a l m a t e r i a l .
P r e p a r a t i o n and P u r i f i c a t i o n o f N i t r o Compounds
2 - N i t r o p r o p a n e . — 2 - N i t r o p r o p a n e (500 m l . , Commercial S o l v e n t s
C o r p o r a t i o n ) was p u r i f i e d by t h e f o l l o w i n g p r o c e d u r e . The c o m m e r c i a l
m a t e r i a l was w a sh e d w i t h t h r e e 250 ml . p o r t i o n s o f s a t u r a t e d , a q u e o u s
s o d i u m b i c a r b o n a t e . The o r g a n i c l a y e r was d r i e d w i t h magnesium
s u l f a t e , f i l t e r e d an d d i s t i l l e d f rom b o r i c a c i d t h r o u g h a V i g e a u x
co lumn (6 i n . ) t o y i e l d a w a t e r w h i t e m a t e r i a l w h ich b o i l e d a t 1 1 8 -
120° ( u n c o r r e c t e d ) . The f i r s t 40 ml . o f d i s t i l l a t e , as c o l l e c t e d i n
a D e a n - S t a r k t r a p , was w e t and was d i s c a r d e d . A p o r t i o n o f t h e
r e m a i n i n g m a t e r i a l was f u r t h e r p u r i f i e d by p r e c i s i o n r e c t i f i c a t i o n
( 1 1 1 ) . The d i s t i l l a t i o n was f o l l o w e d by g a s c h r o m a t o g r a p h i c
m e t h o d s ( 1 1 1 ) . The f r a c t i o n r e t a i n e d f o r t h e s e s t u d i e s was a t l e a s t
( 1 11) See G e n e r a l P r o c e d u r e s and T e c h n i q u e s .
99% p u r e by g a s c h r o m a t o g r a p h y . The i n f r a r e d s p e c t r u m o f t h i s
s a m p l e o f 2 - n i t r o p r o p a n e c o n t a i n e d no a b s o r p t i o n ban d s f o r f u n c t i o n a l
g r o u p s o t h e r t h a n t h e n i t r o g r o u p .
94
N i t r o c y c l o b u t a n e . — N i t r o c y c l o b u t a n e was p r e p a r e d by o x i d a t i o n
o f c y c l o b u t a n o n e oxime a c c o r d i n g t o t h e m e t h o d o f Emmons and
P a g a n o (112) f o r s y n t h e s i s of p h e n y l n i t r o m e t h a n e f rom b e n z a l d e h y d e
(112) W. D. Emmons and A. S . P a g a n o , J . Am. Chem. S o c . , 77 , 4557 ( 1 9 5 5 ) .
o x i m e .
C y c l o b u t a n o n e ( 5 . 0 4 g . , 0 . 0 7 1 9 m o l e , A l d r i c h C h em ica l
Company) was d i s s o l v e d i n a n e t h a n o l - w a t e r s o l u t i o n o f h y d r o x y l a m i n e
h y d r o c h l o r i d e ( 9 . 7 3 g . , 0 . 1 4 2 mole) wh ose "pH" ( e v a l u a t e d w i t h
i n d i c a t o r p a p e r ) h ad b e e n a d j u s t e d to a p p r o x i m a t e l y 6 by t h e a d d i t i o n
o f so d iu m b i c a r b o n a t e . The s o l u t i o n was r e f l u x e d f o r 1 h o u r , c o o l e d
an d p o u r e d i n t o ' ' w a t e r (60 0 m l . ) s a t u r a t e d w i t h so d ium c h l o r i d e an d
l a y e r e d w i t h d i e t h y l e t h e r (100 m l . ) . The a q u e o u s l a y e r was e x
t r a c t e d w i t h 15-100, m l p o r t i o n s o f e t h e r . The o r g a n i c l a y e r was
d r i e d o v e r n i g h t w i t h magnesium s u l f a t e an d t h e n t h e . e t h e r was
removed a t r e d u c e d p r e s s u r e t o y i e l d a w h i t e s o l i d ( 7 . 0 4 g . ) a s s u m e d
t o be c y c l o b u t a n o n e o x i m e . A s m a l l p o r t i o n o f t h i s m a t e r i a l was
d i s s o l v e d i n w a t e r an d a n a l y z e d by f l a m e i o n i z a t i o n gas c h r o m a t o
g r a p h y . Two m a j o r c o m p o n e n t s we re p r e s e n t . The i n f r a r e d s p e c t r u m
o f t h e m a t e r i a l i n d i c a t e d t h e p r e s e n c e o f -OH, and -C=N-, g r o u p s .
The u n p u r i f i e d c y c l o b u t a n o n e oxime w a s o x i d i z e d w i t h p e r -
o x y t r i f l u o r o a c e t i c a c i d a c c o r d i n g t o t h e m e t h o d o f Emmons and
95
P a g a n o t o y i e l d n i t r o c y c l o b u t a n e ( 1 . 6 0 g . , 0 . 0 1 5 7 m o l e , 21.8% b a s e d
on c y c l o b u t a n o n e ) a s i s o l a t e d and p u r i f i e d by p r e p r a t i v e gas
c h r o m a t o g r a p h y o f t h e c r u d e r e a c t i o n p r o d u c t . The k i n e t i c m a t e r i a l
was shown by g a s c h r o m a t o g r a p h y t o b e g r e a t e r t h a n 99% p u r e . The
i n f r a r e d s p e c t r u m o f t h e k i n e t i c s a m p l e o f n i t r o c y c l o b u t a n e
i n d i c a t e d t h e p r e s e n c e o f no f u n c t i o n a l g r o u p s o t h e r t h a n t h e n i t r o
g r o u p .
N i t r o c y c l o p e n t a n e . — N i t r o c y c l o p e n t a n e (11 3) was shown t o b e
(11 3) P r e p a r e d by S . S . Raw alay a t The Ohio S t a t e U n i v e r s i t y .
g a s c h r o m a t o g r a p h i c a l l y p u r e . I t was u s e d i n t h e s e s t u d i e s w i t h o u t
f u r t h e r p u r i f i c a t i o n . The i n f r a r e d s p e c t r u m o f t h i s s am p le o f
n i t r o c y c l o p e n t a n e c o n t a i n e d no f u n c t i o n a l g r o u p s o t h e r t h a n t h e
n i t r o g r o u p .
N i t r o c y c l o h e x a n e . — N i t r o c y c l o h e x a n e (E . I . du P o n t de Nemours
an d Company) was p u r i f i e d by p r e c i s i o n r e c t i f i c a t i o n (111) t o y i e l d
a w a t e r w h i t e m a t e r i a l . Gas c h r o m a t o g r a p h y showed t h a t t h e f r a c t i o n
r e t a i n e d f o r t h e s e s t u d i e s c o n t a i n e d o n l y a b o u t 1% o f u n i d e n t i f i e d
s t a r t i n g i m p u r i t i e s . The i n f r a r e d s p e c t r u m o f t h e d i s t i l l e d
m a t e r i a l r e v e a l e d t h a t n o f u n c t i o n a l g r o u p s w e r e p r e s e n t o t h e r t h a n
t h e n i t r o g r o u p .
9 6
N i t r o c y c l o l i e p t a n e . — N i t r o c y c l o h e p t a n e was p r e p a r e d by r e a c t i o n
o f c y c l o h e p t y l b r o m i d e w i t h sod ium n i t r i t e i n d i m e t h y l f o r m a r a i d e
a c c o r d i n g t o t h e m e th o d d e s c r i b e d by Kornblum (114) f o r s y n t h e s i s o f
(1 1 4 ) N. K o rn b lu m , H. 0 . L a r s o n , R. K. B lack w o o d , IJ. 0 . M o o b e r r y , E. P . O l i v e t o and G. E. Graham, J . Am. C’nem. S o c . , 7 8 , 1497 ( 1 9 5 6 ) .
2 - n i t r o o c t a n e f rom 2 - b r o m o o c t a n e . P r e c i s i o n r e c t i f i c a t i o n o f t h e
r e a c t i o n p r o d u c t y i e l d e d n i t r o c y c l o h e p t a n e (1 1 .2 g . , 0 . 0 7 8 2 m o l e ,
26 .2% b a s e d on c y c l o h e p t y l b r o m i d e ) whici i was gas c h r o m a t o g r a p h i c a l l y
p u r e . I t s i n f r a r e d s p e c t r u m r e v e a l e d t h a t no f u n c t i o n a l g r o u p s
o t h e r t h a n t h e n i t r o g r o u p w e re p r e s e n t . I t d i d n o t c o n t a i n any
b a n d s f r om c y c l o h e p t y l b r o m i d e .
N i t r o c y c l o o c t a n e . — N i t r o c y c l o o c t a n e was p r e p a r e d f r o m c y c l o -
o c t y l b r o m i d e and s o d i u m n i t r i t e i n d i m e t h y l f o r m a m i d e a c c o r d i n g t o
t h e m e th o d f o r s y n t h e s i s o f 2 - n i t r o o c t a n e f rom 2 - b r o m o o c t a n e ( 1 1 4 ) .
The r e a c t i o n p r o d u c t , a f t e r p u r i f i c a t i o n by p r e c i s i o n r e c t i f i c a t i o n ,
y i e l d e d n i t r o c y c l o o c t a n e ( 4 . 0 7 g . , 0 . 0 2 6 m o l e , 8.7% b a s e d on c y c l o -
o c t y l b r o m i d e ) w h i c h was a t l e a s t 96% p u r e by gas c h r o m a t o g r a p h y .
The i n f r a r e d s p e c t r u m o f t h i s compound c o n t a i n e d no f u n c t i o n a l
g r o u p s o t h e r t h a n t h e n i t r o g r o u p . I t d i d n o t c o n t a i n an y b a n d s
f r o m c y c l o o c t y l b r o m i d e . The m a t e r i a l was s u f f i c i e n t l y p u r e t o
y i e l d k i n e t i c d a t a o f h i g h p r e c i s i o n .
97
The i n f r a r e d s p e c t r a o f t h e p r e s e n t n i t r o c y c l o a l k a n e s w e r e ,
f o r a l l p u r p o s e s , i d e n t i c a l w i t h t h o s e t a k e n by F l a n a g a n (19 ) f o r
t h e compounds u s e d i n h i s w o r k .
E q u i p m e n t f o r D e t e r m i n a t i o n o f R a t e s o f N e u t r a l i z a t i o n
and I o n i z a t i o n C o n s t a n t s
C o n s t a n t T e m p e r a t u r e C o n t r o l . — Any w i d e m o u th , i n s u l a t e d
v e s s e l was s u i t a b l e f o r t h e k i n e t i c s t u d i e s a t 0 ° . The b a t h was
f i l l e d w i t h c r u s h e d i c e and d i s t i l l e d w a t e r t o form a t h i c k s l u s h .
O c c a s i o n a l man ual s t i r r i n g m a i n t a i n e d a c o n s t a n t t e m p e r a t u r e .
F l u c t u a t i o n s i n t e m p e r a t u r e were n o t s u f f i c i e n t l y l a r g e t o b e
d e t e c t e d by a Beckman T h e r m o m e te r .
A S a r g e n t c o n s t a n t t e m p e r a t u r e w a t e r b a t h s y s t e m (Model S-
84 8 0 5 ) was u s e d f o r k i n e t i c r u n s a t 1 0 . 0 - 0 . 0 5 ° and 2 0 . 0 - 0 . 0 5 ° .
I t was m o d i f i e d t o a l l o w f o r more f l e x i b l e o p e r a t i o n . The m e r c u r y
t h e r m o r e g u l a t o r was r e p l a c e d w i t h a t h e r m i s t o r a c t i v a t e d , z e r o
v o l t a g e s w i t c h t r i g g e r c i r c u i t ( G e n e r a l E l e c t r i c PA 424) w h i c h c o n
t r o l l e d a 500 w a t t r a p i d r e s p o n s e i m m e r s i o n h e a t e r . The c o i l p r o
v i d e d t o o p e r a t e t h e b a t h b e l o w room t e m p e r a t u r e was a l s o r e p l a c e d
w i t h a r e f r i g e r a t i o n u n i t . The h e a t e x c h a n g e c o i l o f t h i s u n i t
was p l a c e d i n a v e r t i c a l c y l i n d e r a r o u n d t h e c e n t r a l h e a t i n g and
c i r c u l a t i n g u n i t o f t h e S a r g e n t s y s t e m .
A l l w a t e r b a t h s w e r e g ro unde d t o o b t a i n more s t a b l e c e l l
r e s i s t a n c e m e a s u r e m e n t s . G ro u n d in g was a c c o m p l i s h e d by i m m e r s i n g
98
t h e b a r e d end o f a n i n s u l a t e d l e a d w i r e b e n e a t h t h e s u r f a c e o f t h e
w a t e r and c o n n e c t i n g i t s o t h e r end t o a s i n k f a u c e t .
C o n d u c t i v i t y B r i d g e . — An I n d u s t r i a l I n s t r u m e n t s C o n d u c t i v i t y
B r i d g e (Model RC-18) was u s e d t o m easu re c e l l r e s i s t a n c e . The
i n s t r u m e n t was a s e l f - c o n t a i n e d , r e s i s t a n c e - c a p a c i t a n c e b r i d g e ,
r . f . o s c i l l a t o r an d c a t h o d e r a y o s c i l l o s c o p e n u l l d e t e c t o r . The
i n s t r u m e n t had a s e l e c t i o n o f two f r e q u e n c i e s , 1-KC and 3-KC and
was c a p a b l e o f m e a s u r i n g c e l l r e s i s t a n c e (R) o r c e l l c o n d u c t i v i t y
( 1 / R ) d i r e c t l y . A s c h e m a t i c d i ag ra m o f t h e i n s t r u m e n t i s s h o ’.ra i n
F i g u r e A. A s h i e l d e d l e a d was used t o c o n n e c t t h e b r i d g e c i r c u i t
t o t h e t e r m i n a l p o s t s o f t h e c o n d u c t i v i t y c e l l .
C o n d u c t i v i t y C e l l s . — The c o n d u c t i v i t y c e l l s were o f s p e c i a l
d e s i g n a s i l l u s t r a t e d i n F i g u r e s 5 and 6 . The s m a l l vo lum es o f t h e
c e l l s f a c i l i t a t e u s e o f s m a l l amounts o f m a t e r i a l and make more
s t a b l e m e a s u r e m e n t s p o s s i b l e . The u s e o f c a p i l l a r y t u b i n g t o h o u s e
p l a t i n u m e l e c t r o d e l e a d s h a s two m a jo r a d v a n t a g e s o v e r t h e d e s i g n
u s e d by p r e v i o u s w o r k e r s ( 1 9 , 5 7 ) . The c a p i l l a r y t u b i n g i s much l e s s
s u s c e p t i b l e t o b r e a k a g e t h a n t h e t h i n w a l l e d , s m a l l d i a m e t e r t u b i n g
u s e d p r e v i o u s l y f o r m e r c u r y l e a d s . The p l a t i n u m l e a d s s o l d e r e d t o
b r a s s t e r m i n a l p o s t s w h i c h w ere i n t u r n a n c h o r e d t o t h e end o f t h e
c a p i l l a r y by means o f e p o x i d e r e s i n p r o v i d e d a much n e a t e r , more
t r o u b l e - f r e e c o n n e c t i o n t h a n t h e mercu ry r e s e r v o i r .
99
B r i d g e i n P o s i t i o n t o M e a s u r e R e s i s t a n c e
A m p l i f i e r
Generator
Cell
C R O6 D e c o d e Re s i s t o r
W a g n e r G r o u n d
S e l e c t o rW a g n e r G r o u n d B o l a n c e
B r i d g e i n P o s i t i o n t o M e a s u r e C o n d u c t a n c e
A m p l i f i e r
6 D e c o d e R e s i s t o r
G e n e r a t o r
10 KC R O
W a g n e r G r o u n d S e l e c t o r
W a g n e r G r o u n d B a l a n c e
F i g u r e 4 . C i r c u i t Diag ram o f I n d u s t r i a l I n s t r u m e n t s , I n c . Model RC-18 C o n d u c t i v i t y B r i d g e
100
B ra ss p ost so l de red to 2 0 g o u g e p l a t i num j o i n e d to c a p i l l a r y wi th e p o x i d e resin.
35 3 5
9 . 4cm
cm
2.5cmc m cm
F i g u r e 5 . D iag ram o f C o n d u c t i v i t y C e l l Used t o M e a s u re R e s i s t a n c e o f S o l u t i o n s w i t h Low Impedance
101
B r a s s p o s t so l de red to 2 0 gau ge plat inurn, joined to c a p i l l a r y wi th e p o x i d e resin.
/a
35
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n . A
9 . 4cm
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1.5cm
2 .5 4 2 .cm cm
^ 2.5 ^ cm
F i g u r e 6 . D iag r am o f C o n d u c t i v i t y C e l l Used t o M ea s u re R e s i s t a n c e o f S o l u t i o n s w i t h High Impedance
102
The c h o i c e o f e l e c t r o d e geom et ry d e p e n d e d upon th e s y s t e m
b e i n g s t u d i e d . F o r e x a m p l e , i n t h e am ine c a t a l y s i s s t u d i e s , t h e
e l e c t r o d e s w e r e c i r c u l a r w i t h a d i a m e t e r o f 1 . 1 0 cm. and a s e p a r a t i o n
o f 2 .5 cm. H o w ev er , i n t l ie v e r y d i l u t e s y s t e m s u s e d t o s t u d y
h y d r o x i d e i o n c a t a l y s i s , i t was n e c e s s a r y t o d e c r e a s e t h e e l e c t r o d e
s e p a r a t i o n and i n c r e a s e t h e i r a r e a s s i g n i f i c a n t l y i n o r d e r t o b r i n g
c e l l r e s i s t a n c e s i n t o t h e ra nge o f t h e i n s t r u m e n t . These d e s i g n
f e a t u r e s a r c i l l u s t r a t e d i n F i g u r e s
S y r i n g e s . — The s y r i n g e s u sed t o i n j e c t t h e n i t r o compounds
i n t o t h e r e a c t i o n v e s s e l were o f th e m i c r o l i t e r t y p e . A H a m i l t o n
701-H m i c r o l i t e r s y r i n g e ( c a p a c i t y 10 m i c r o l i t e r s ) o r a m i c r o m e t e r
s y r i n g e (R oger G i l m o n t I n d u s t r i e s , c a p a c i t y 0 . 2 m l . ) was u sed w i t h
e q u a l a c c u r a c y i n d e t e r m i n a t i o n o f t h e k i n e t i c c o n s t a n t s .
P o t e n t i o m e t e r . — A Beckman R e s e a r c h pH m e t e r (Model 101900)
was used t o make a l l p o t e n t i o r a e t r i c m e a s u r e m e n t s . I t was e q u i p p e d
w i t h a C o r n i n g c a l o m e l r e f e r e n c e e l e c t r o d e (4 7 6 0 0 2 ) and a C o r n i n g ,
t r i p l e - p u r p o s e g l a s s e l e c t r o d e (4 7 6 0 2 2 ) . The m e a s u r i n g c i r c u i t
was g ro u n d ed by r u n n i n g a l e a d f rom t h e a lu m in u m l o o p s s u p p o r t i n g
t h e pH c e l l s i n t h e t h e r m o s t a t e d b a t h t o a s i n k f a u c e t .
pH C e l l s . — The c e ] . l s used to m e a s u r e pH w e r e d e s i g n e d
s i m i l a r t o t h e s t a n d a r d G r i f f i n b e a k e r . They w e r e made o f 47 mm.
I . D . t h i c k - w a l l e d p y r e x t u b i n g . The mouth o f t h e c e l l was f l a r e d
103
s l i g h t l y t o a l l o w t h e c e l l t o b e s e a l e d w i t h a nu m b er 11 n e o p r e n e
s t o p p e r . The e l e c t r o d e s and i n l e t - o u t l e t t u b e s ( f o r i n t r o d u c t i o n o f
a n i n e r t a t m o s p h e r e ) w e r e a l s o mounted i n t h e same s i z e s t o p p e r and
t h i s u n i t was f i t t e d i n t o t h e c e l l when m e a s u r e m e n t s w e re b e i n g
made. The c e l l c a p a c i t y was 45 t o 50 m l .
P r e p a r a t i o n of R e a g e n t s and S o l u t i o n s
H y d r o x id e I o n C a t a l y s i s . — The s o l v e n t u s e d t o s t u d y t h e
n e u t r a l i z a t i o n o f n i t r o compounds by h y d r o x i d e i o n was 50% by vo lume
1 , 2 - d i m e t h o x y e t h a n e - w a t e r t o p e r m i t c o m p a r i s o n o f t h e s e r e s u l t s w i t h
- 4p r e v i o u s s t u d i e s ( 1 8 , 1 9 , 2 4 ) . Use o f s m a l l a m o u n t s o f b a s e (10 N)
made i t n e c e s s a r y t o p u r i f y t h e g lyme a c c o r d i n g t o t h e method s o f
F i e s e r (115) f o r c o m m e r c i a l 1 , 4 - d i o x a n e . F o r 1 , 2 - d i m e t h o x y e t h a n e ,
(115) L . F . F i e s e r , " E x p e r i m e n t s i n O r g a n i c C h e m i s t r y " , 3 r d E d i t i o n R e v i s e d , D. C. H e a t h and Co. ( 1 9 5 7 ) , p . 284 .
t h e n i t r o g e n sweep was e l i m i n a t e d and t h e r e f l u x t i m e s w e re 12 h o u r s
o r more .
A s t o c k s o l u t i o n o f sod ium h y d r o x i d e ( 0 . 0 0 1 ÎJ) was p r e p a r e d
by d i l u t i n g an a l i q u o t ( 5 . 0 0 m l . ) o f c a r b o n a t e f r e e sod ium h y d r o x i d e
(The Ohio S t a t e U n i v e r s i t y R e a g e n t L a b o r a t o r y , 0 . 1 0 0 ^ ) i n a
v o l u m e t r i c f l a s k (500 m l . ) w i t h d i m i n e r a l i z e d d o u b l e d i s t i l l e d
w a t e r . An a l i q u o t ( 1 0 . 0 0 m l . ) o f t h i s s t o c k s o l u t i o n a d d e d to an
104
a l i q u o t ( 1 0 . 0 0 m l . ) o f f r e s h l y d i s t i l l e d 1 , 2 - d i i n e t h o x y e t h a n e was
d i l u t e d w i t h t h e s o l v e n t m i x t u r e i n a t h e r m o s t a t e d v o l u m e t r i c
f l a s k (100 m l . ) t o y i e l d t h e k i n e t i c s o l u t i o n o f sodium h y d r o x i d e
(0 .0 0 0 1 . The s t o c k s o l u t i o n s o f so d iu m h y d r o x i d e w e re t e s t e d
p e r i o d i c a l l y f o r c a r b o n a t e i o n by a d d i t i o n o f an a l i q u o t (10 m l . )
o f b a r iu m c h l o r i d e s o l u t i o n (1 1 m l . ) . I f t h e r e s u l t i n g
s o l u t i o n became c l o u d y , i n d i c a t i n g t h e p r e s e n c e of b a r iu m c a r b o n a t e ,
t h e s o l u t i o n was d i s c a r d e d . S t o c k s o l u t i o n s w e re s t o r e d u n d e r
a r g o n .
M e t h o x i d e I o n C a t a l y s i s .— M e t h a n o l ( J . T. Baker C h e m i c a l
Company, r e a g e n t ) u s e d i n t h e s t u d y o f n e u t r a l i z a t i o n o f n i t r o
compounds by m e t h o x i d e i o n was d r i e d by d i s t i l l a t i o n f rom mag
n e s iu m a c c o r d i n g t o t h e p r o c e d u r e o f F i e s e r ( 1 1 6 ) . A s t o c k s o l u t i o n
(116) L. F . F i e s e r , 0 £ . c i t . , p . 289 .
o f sodium m e t h o x i d e ( 0 . 1 ^ ) i n m e t h a n o l was p r e p a r e d by r e a c t i o n o f
f r e s h l y c u t ( s i l v e r w h i t e ) so d iu m m e t a l i n a known volume o f d r i e d
m e t h a n o l w h i l e f l u s h i n g t h e f l a s k w i t h a s t r e a m o f d r y a r g o n . An
a l i q u o t ( 5 . 0 0 m l . ) o f t h i s s o l u t i o n was a d d e d to a volume o f w a t e r
( a b o u t 25 m l . ) and s t a n d a r d i z e d by t i t r a t i o n a g a i n s t s t a n d a r d
h y d r o c h l o r i c a c i d . The s o l u t i o n was t h e n d i l u t e d t o t h e d e s i r e d
105
v o lu m e t o y i e l d a s t o c k s o l u t i o n o f s o d i u m m e t h o x i d e ( 0 . 1 _N) i n
m e t h a n o l . An a l i q u o t ( 1 .0 0 m l . ) o f t h e s t o c k s o l u t i o n was d i l u t e d
w i t h d r y m e t h a n o l i n a dr y v o l u m e t r i c f l a s k , w h ich had b e e n
p r e v i o u s l y f l u s h e d w i t h a r g o n and t h e r m o s t a t e d a t 0 . 0 0 ° , t o y i e l d
t h e k i n e t i c s o l u t i o n (0 .0 0 1 _d) i n so d iu m m e t h o x i d e . A l l s o l u t i o n s
o f so d iu m m e t h o x i d e w e re p r e p a r e d f r o m m e t h a n o l d i s t i l l e d j u s t
p r i o r t o m i x i n g a n d p r o t e c t e d f rom a t m o s p h e r i c m o i s t u r e by s t o r a g e
u n d e r a r g o n .
E t h o x i d e I o n C a t a l y s i s . — E t h a n o l , u s e d t o s t u d y n e u t r a l i z a t i o n
o f n i t r o compounds by e t h o x i d e i o n , was d r i e d by two p r o c e d u r e s .
The e t h a n o l t h u s p r e p a r e d gave t h e same k i n e t i c r e s u l t s . One
m e th o d em p lo y ed t h e p r o c e d u r e which l l i n e and c o - w o r k e r s u s e d t o
d r y i s o p r o p y l a l c o h o l (117 ) and m e t h a n o l (1 18 ) . A b s o l u t e e t h a n o l
(117 ) J . H i n e , L. G. Mahone, a n d C. L. l o t t a , J . Am. Chem. S o c . , 89_, 5911 ( 1 9 6 7 ) .
(118 ) J . n i n e and K. T a n a b e , i b i d . , 62 , 1463 ( 1 9 5 8 ) .
( U . S . I n d u s t r i a l C h e m i c a l s Company, r e a g e n t , 900 m l . ) was p l a c e d
i n a 1 - l i t e r ro u n d b o t t o m f l a s k and s o d i u m m e t a l (7 g . ) was a d d e d
w h i l e a s t r e a m o f a r g o n was p a s s e d o v e r t h e s u r f a c e o f t h e l i q u i d .
A f t e r t h e so d iu m h a d r e a c t e d , d i e t h y l p h t h a l a t e (30 g . ) was a d d e d
a n d t h e s y s t e m r e f l u x e d f o r 3 h o u r s . The e t h a n o l was d i s t i l l e d
106
and u s e d i m m e d i a t e l y t o p r e p a r e k i n e t i c s o l u t i o n s . The o t h e r
method i n v o l v e d a b s o l u t e e t l i a n o l (U .S . I n d u s t r i a l C h em ica l s
Company, r e a g e n t , 500 m l . ) w h ich had b e e n s t o r e d o v e r m o l e c u l a r
s i e v e s ( F i s l i c r S c i e n t i f i c Company, 4 A) f o r a t l e a s t 12 h o u r s and
t h e n u s e d d i r e c t l y t o p r e p a r e t h e k i n e t i c s o l u t i o n s .
S t o c k and k i n e t i c s o l u t i o n s o f sodium e t h o x i d e w e re p r e
p a r e d i n a manner i d e n t i c a l t o t h a t o f s t a n d a r d sodium m e t h o x i d e
s o l u t i o n s .
G l y c o l a t e I o n C a t a l y s i s . — E t h y l e n e g l y c o l , u s e d to s t u d y
n e u t r a l i z a t i o n o f n i t r o compounds by g l y c o l a t e i o n , was p u r i f i e d
i n t l ie f o l l o w i n g m an n e r . E t h y l e n e g l y c o l ( M a th e s o n , Coleman, and
B e l l , r e a g e n t , 2 , 5 0 0 m l . ) was p l a c e d i n a 3 - l i t e r ro u n d b o t t o m
f l a s k . P o t a s s i u m h y d r o x i d e ( A l l i e d C h em ica l Company, r e a g e n t ,
10 g . ) was added to t h e g l y c o l and t h e t e m p e r a t u r e o f t l ie m i x t u r e
r a i s e d t o a c h i e v e s o l u t i o n . D u r i n g t h i s t i m e , t h e f l a s k was
f l u s h e d w i t h a r g o n . When a l l t h e p o t a s s i u m h y d r o x i d e was i n
s o l u t i o n , t h e f l a s k was f i t t e d w i t h a d i s t i l l a t i o n column (2 4"
p a c k e d w i t h 6 mm. g l a s s b e a d s ) an d t h e e t h y l e n e g l y c o l was d i s
t i l l e d u n d e r a r g o n a t a t m o s p h e r i c p r e s s u r e . The f i r s t f r a c t i o n
(250 m l . ) was l a r g e l y w a t e r and was d i s c a r d e d a l o n g w i t h a s e c o n d
f r a c t i o n (300 m l . ) o f e t h y l e n e g l y c o l . A c e n t e r c u t ( 1 , 2 0 0 m l . )
was t h e n c o l l e c t e d i n t h r e e ro u n d b o t t o m f l a s k s (500 m l . ) w h ic h
107
h a d b e e n d r i e d , c h a r g e d w i t l i m o l e c u l a r s i e v e s ( F i s h e r S c i e n t i f i c
Company 4A) , f l u s h e d w i t h a r g o n , i n t r o d u c e d i n t o t h e d i s t i l l a t i o n
s y s t e m , f l am e d w i t h a F i s h e r b u r n e r and a l l o w e d t o c o o l b e f o r e any
d i s t i l l a t e was c o l l e c t e d . Each f r a c t i o n was i m m e d i a t e l y d e g a s s e d
b y h e a t i n g t h e g l y c o l u n d e r r e d u c e d p r e s s u r e t o b o i l i n g t h e n b a c k -
f l u s h i n g w i t h a r g o n 3 t i m e s t h r o u g h an a d a p t e r ( 2 4 / 4 0 ) w i t h a
T e f l o n s t o p c o c k (4 mm.) .
Sodium g l y c o l a t e ( 0 . 1 - 0 . 2 N) i n e t h y l e n e g l y c o l was p r e
p a r e d by a d d i n g a s m a l l p i e c e o f f r e s h l y c u t so d iu m t o a f l a s k a t
room t e m p e r a t u r e w h i c h h ad b e e n d r i e d by f l a m i n g t h e w a l l s , c h a r g e d
w i t h m o l e c u l a r s i e v e s , e v a c u a t e d w h i l e s t i l l h o t , b a c k - f l u s h e d w i t h
a r g o n and t h e n f u r t h e r d r i e d and p u r g e d by a l l o w i n g a s t r e a m o f
a r g o n t o p a s s t h r o u g h t h e f l a s k f o r 15 m i n u t e s w h i l e i n t e r m i t t e n t l y
f l a m i n g t h e w a l l s o f t i i e f l a s k . The a r g o n i n l e t was a h y p o d e r m i c
n e e d l e (16 g a . ) i n s e r t e d i n t o a serum cap f i t t e d t o t h e n e c k o f an
a d a p t e r o f t h e t y p e e m p lo y ed a b o v e . The a d a p t e r was h e l d i n t l ie
f l a s k w i t h a j o i n t c l a m p ( K o n t e s G l a s s I n c . , Kem-Klamp) . The t i p
o f t ' l e n e e d l e was p o s i t i o n e d above t h e s u r f a c e o f t h e l i q u i d i n t h e
f l a s k . The e x i t p o r t was a h y p o d e rm ic n e e d l e (18 g a . ) w h ich j u s t
p e n e t r a t e d t h e s e p t u m . E t h y l e n e g l y c o l was t r a n s f e r r e d t o t h e
f l a s k . A f t e r t h e s o d i u m h a d r e a c t e d , an a l i q u o t (1 m l . ) o f t h e
s o d i u m g l y c o l a t e s o l u t i o n was removed, a d d e d t o w a t e r (25 m l . ) a n d
t i t r a t e d w i t h s t a n d a r d h y d r o c h l o r i c a c i d . The so d iu m g l y c o l a t e
108
s o l u t i o n was t h e n d i l u t e d a t room t e m p e r a t u r e w i t h e t l i y l e n e g l y c o l
t o y i e l d a s t o c k s o l u t i o n o f sod ium g l y c o l a t e ( 0 . 2 6 0 ^ ) . An a p p r o p
r i a t e a l i q u o t o f t h i s s o l u t i o n was t h e n d i l u t e d a t room t e m p e r a t u r e
w i t h e t h y l e n e g l y c o l i n a f l a s h t h a t h ad b e e n d r i e d , c h a r g e d w i t h
m o l e c u l a r s i e v e s and f i l l e d w i t h a r g o n , a s d e s c r i b e d a b o v e , to
y i e l d a k i n e t i c s o l u t i o n o f so d iu m g l y c o l a t e ( 0 . 0 0 1 t o 0 . 0 0 0 1 '£)
i n e t h y l e n e g l y c o l .
A l l s o l u t i o n s w ere p r e p a r e d f rom e t h y l e n e g l y c o l which had
b e e n d i s t i l l e d , and d e g a s s e d a s d e s c r i b e d . A l l t r a n s f e r s were
Tvide w i t h s y r i n g e s w h ich had b e e n d r i e d , f l u s h e d w i t h a r g o n , f i t t e d
w i t h a t h r e e - w a y p l a s t i c v a l v e (Ace G l a s s I n c . , e q u i p p e d w i t h L u e r
h u b s ) an d a s p e c i a l h y p o d e r m i c n e e d l e ( H a m i l t o n C o . , 10 g a . , 12 i n . ) .
(Tlie t l i ree - ' . ; ay v a l v e p r o v i d e d a c o n v e n i e n t i n l e t f o r a r g o n so t h e
s y s t e m c o u l d b e f l u s h e d b e f o r e and a f t e r a n a l i q u o t was w i t h d r a w n . )
T r i e t h y l a m i n e C a t a l y s i s . — The s o l v e n t u s e d t o s t u d y n e u t r a l
i z a t i o n o f n i t r o c y c l o a l k a n e s by t r i e t h y l a m i n e was a m i x t u r e o f 1 , 2 -
d i m e t h o x y e t h a n e and w a t e r (50% by v o l u m e ) . T h i s s y s t e m p e r m i t t e d
t h e p r e s e n t r e s u l t s t o b e com par ed w i t h t h o s e f rom p r e v i o u s s t u d i e s
i n t h i s l a b o r a t o r y (19) .
1 , 2 - D i m c t h o x y e t h a n e (M a th e s o n , C o lem a n , and B e l l , r e a g e n t )
was p u r i f i e d upon s t o r a g e f o r a t l e a s t 24 h o u r s o v e r p o t a s s i u m
h y d r o x i d e ( A l l i e d C h e m i c a l Company, r e a g e n t ) , f i l t r a t i o n , and
d i s t i l l a t i o n f rom c a l c i u m h y d r i d e ( M e t a l H y d r i d e s I n c o r p o r a t e d ) .
109
The p u r i t y o f t h e d i s t i l l e d m a t e r i a l was a t t e s t e d by g a s c h r o m a t o
g r a p h y ( 1 1 1 ) . W a te r (The Ohio S t a t e U n i v e r s i t y R e a g e n t L a b o r a t o r y ,
d e m i n e r a l i z e d , d o u b l e d i s t i l l e d ) was r e f l u x e d and d i s t i l l e d from
p o t a s s i u m p e r m a n g a n a t e .
T r i e t h y l a m i n e ( M a th e s o n , Coleman , and B e l l , r e a g e n t ) was
d i s t i l l e d f r o m c a l c i u m h y d r i d e . I t s p u r i t y was e s t a b l i s h e d by gas
c h r o m a t o g r a p h y . S t a n d a r d k i n e t i c s o l u t i o n s i n 1 , 2 - d i m e t h o x y e t h a n e -
w a t e r (50% by v o lu m e) w ere p r e p a r e d by w e i g h i n g t r i e t h y l a m i n e
( 2 . 1 - 2 . 2 g . , 0 . 2 1 - 0 . 2 2 m o le ) i n t o a t a r e d , s t o p p e r e d b o t t l e and
t h e n d i l u t i n g t h e s a m p l e w i t h t h e s o l v e n t a t t h e t e m p e r a t u r e of
t h e b a t h i n a v o l u m e t r i c f l a s k (100 m l . ) t o y i e l d a k i n e t i c s o l u t i o n
o f t r i e t h y l a m i n e ( 0 . 2 1 M).
S o l u t i o n s w e r e a l w a y s p r e p a r e d f rom r e a g e n t s d i s t i l l e d j u s t
p r i o r t o m i x i n g .
D e t e r m i n a t i o n o f A p p a r e n t I o n i z a t i o n C o n s t a n t s o f N i t r o
c y c l o a l k a n e s . — The s o l v e n t u s e d t o s t u d y t h e i o n i z a t i o n c o n s t a n t s o f
t h e C-4 t h r o u g h C-8 n i t r o c y c l o a l k a n e s was m e t h a n o l (33.3% by w e ig l i t )
and w a t e r (66.7% by w e i g h t ) .
The s o l v e n t was p r e p a r e d by m i x in g m e t h a n o l ( A l l i e d C hem ical
C o . , r e a g e n t , 424 m l . , 333 g . , room t e m p e r a t u r e ) and w a t e r (The
Ohio S t a t e U n i v e r s i t y R e a g e n t L a b o r a t o r y , d e m i n e r a l i z e d , d o u b l e
d i s t i l l e d , 667 m l . , 667 g . , room t e m p e r a t u r e ) and a l l o w i n g t h e
m i x t u r e t o come t o room t e m p e r a t u r e .
110
Two s t a n d a r d b u f f e r s w e re p r e p a r e d . I n o n e , sod ium t e t r a
b o r a t e ( A l l i e d C h e m i c a l C o . , r e a g e n t , 1 . 9 4 5 g . , 0 . 0 0 5 0 9 9 mole) and
p o t a s s i u m c h l o r i d e ( A l l i e d C hem ica l C o . , r e a g e n t , 0 . 7 5 3 8 g . , 0 . 0 1 0 1 1
m o l e ) was d i s s o l v e d i n t h e c o - s o l v e n t , m e t h a n o l and w a t e r (1272 m l . ,
1000 g . ) ; i n t h e o t h e r b u f f e r , a c e t i c a c i d ( J . T. B a k e r C h e m i c a l
C o . , r e a g e n t , 0 . 6 8 1 6 g . , 0 . 0 1 1 3 5 m o l e ) , so d iu m a c e t a t e ( J . T. B a k e r
C h e m i c a l C o . , r e a g e n t , 0 . 9 0 8 9 g . , 0 . 0 1 1 0 8 m o l e ) , an d p o t a s s i u m
c h l o r i d e ( A l l i e d C h e m i c a l C o . , r e a g e n t , 0 . 7 5 8 3 g . , 0 . 0 1 0 1 7 m o le )
was d i s s o l v e d i n t h e s o l v e n t m i x t u r e (1272 m l . , 1000 g . ) t o y i e l d
s o l u t i o n s o f pH 9 . 3 7 8 a n d 5 .2 8 9 r e s p e c t i v e l y a s a s s i g n e d by B a t e s
and c o - w o r k e r s (1 19) . The b u f f e r s w e re c h e c k e d a g a i n s t e a ch o t h e r
u s i n g t h e Beckman R e s e a r c h pH M e t e r .
(119) R. G. B a t e s , M. P a a b o , and R. A. R o b i n s o n , J . P h y s , C h em . , 1833 ( 1 9 6 3 ) .
S t a n d a r d s o l u t i o n s o f n i t r o compounds w e r e p r e p a r e d by
w e i g h i n g th e a p p r o p r i a t e amount o f m a t e r i a l i n t o a s m a l l v i a l and
d i l u t i n g i t s c o n t e n t s i n a v o l u m e t r i c f l a s k (250 m l . ) c o n t a i n i n g
p o t a s s i u m c h l o r i d e ( a p p r o x i m a t e l y 0 . 1 8 g . , 0 . 0 0 2 4 m o l e ) w i t h t h e
c o - s o l v e n t .
S t a n d a r d s o l u t i o n s o f sodium h y d r o x i d e w e r e p r e p a r e d by
d i l u t i n g an a l i q u o t ( 1 0 . 0 0 m l . ) o f sodium h y d r o x i d e (The Ohio S t a t e
Ill
U n i v e r s i t y R e a g e n t L a b o r a t o r y , 0 .1 0 0 c a r b o n a t e - f r e e ) and an a l i
q u o t o f m e t h a n o l ( 6 . 3 5 m l . ) i n a v o l u m e t r i c f l a s k (250 m l . ) w i t h
t h e c o - s o l v e n t .
P h y s i c a l M easu re m en ts
H y d r o x i d e I o n C a t a l y s i s .— In p r e p a r a t i o n f o r a k i n e t i c r u n ,
a c l e a n c o n d u c t i v i t y c e l l was r i n s e d w i t h w a t e r (The Ohio S t a t e
U n i v e r s i t y R e a g e n t L a b o r a t o r y , d e i . i i n e r a l i x e d , d o u b l e d i s t i l l e d ) .
The c e l l was d r i e d b y r i n s i n g w i t h a c e t o n e ( J . T. B ak er C h e m i c a l
Company, r e a g e n t ) a n d t h e n p u r g i n g w i t h a s t r e a m o f d r y n i t r o g e n .
The c e l l u t i l i z e d was t l i a t shown i n F i g u r e i n w h ich l a r g e e l e c
t r o d e s a r c s p a c e d v e r y c l o s e t o g e t h e r .
A f t e r d r y i n g , t h e c e l l was p l a c e d i n an i c c - w a t e r b a t h a t
0 . 0 0 ° . An a l i q u o t ( 2 4 . 0 0 m l . ) of t h e k i n e t i c s o l u t i o n ( 0 . 0 0 0 1 II
sod ium h y d r o x i d e i n 50% by volume 1 , 2 - d i m c t h o x y c t h a n e - w a t e r ) was
t r a n s f e r r e d i n t o t h e c e l l w i t h 10 .00 ml . an d 4 . 0 0 ml . p i p e t t e s
p r e v i o u s l y c h i l l e d i n a f r e e z e r t o - 1 0 ° . The e n t i r e s y s t e m was
a l l o w e d t o come t o e q u i l i b r i u m . At t h i s p o i n t , t h e c e l l c o n t e n t s
c o u l d b e s w i r l e d a n d t h e r e s i s t a n c e o f t h e c e l l r e t u r n e d , i n a few
momen ts , t o t h e p r e v i o u s r e s i s t a n c e v a l u e p l u s o r minus 1-2% o f t h e
i n i t i a l r e a d i n g .
At e q u i l i b r i u m , an a l i q u o t ( a r o u n d 0 . 0 1 0 0 m l . ) o f t h e n e a t
n i t r o compound, a t room t e m p e r a t u r e , was t r a n s f e r r e d t o t h e c e l l
w i t h an RGI M i c r o m e t e r s y r i n g e . The c e l l was removed f rom t h e
112
b a t h , i n v e r t e d w i t h a s h a k i n g m o t i o n a n d r a p i d l y r e p l a c e d i n t h e
b a t h . S i n c e t h e k i n e t i c s w e r e f i r s t o r d e r ( l a r g e e x c e s s o f n i t r o
c o m p o u n d ) , z e r o t i m e c o u l d b e s e l e c t e d a t an y p o i n t a f t e r a d d i t i o n
o f t h e s u b s t r a t e . T h e r e f o r e , t h e s y s t e m was a l l o w e d a c e r t a i n
t i m e ( a p p r o x i m a t e l y 0 . 3 m i n . ) f o r t h e e l e c t r o d e - l i q u i d i n t e r f a c e
t o become e s t a b l i s h e d a g a i n b e f o r e t h e l a p s e t i m e r was s t a r t e d a n d ,
a t t h a t momen t , t h e i n i t i a l c e l l r e s i s t a n c e (R^) was r e c o r d e d . The
i n c r e a s e i n c e l l r e s i s t a n c e (R) was m e a s u r e d a t r e g u l a r i n t e r v a l s
o f t i m e . T h i s c h a n g e was f o l l o w e d by a d j u s t i n g t h e b r i d g e d e c a d e
r e a d i n g s t o a r e s i s t a n c e v a l u e g r e a t e r t h a n t h a t o f t h e c e l l so t h a t
i n s t r u m e n t r e a c h e d t h e b a l a n c e p o i n t a t t h e d e s i r e d t i m e .
I n t h e s e e x p e r i m e n t s , t h e r e s i s t a n c e o f t h e c e l l was o b s e r v e d
t o i n c r e a s e t o a maximum (R ) and t h e n b e g a n t o d e c r e a s e v e r ymax
s l o w l y , a p p a r e n t l y due t o t h e d e c o m p o s i t i o n o f t h e n i t r o n a t e i o n .
T h i s s m a l l , c o n t i n u a l c h a n g e i n r e s i s t a n c e was a t t r i b u t e d
t o s u b s e q u e n t d e c o m p o s i t i o n o f t h e n i t r o n a t e a n i o n i n t o t h e more
h i g h l y c o n d u c t i n g n i t r i t e i o n . I n s u b s t a n t i a t i o n o f t h i s , i t h a s
b e e n o b s e r v e d ( 9 1 , 1 2 0 ) t h a t p r o l o n g e d a c t i o n o f b a s e s upon s a l t s o f
(1 2 0 ) E. M. N y g a a rd , J . H. McCracken an d T. T. N o l a n d , P a t . 2 , 3 7 0 , 1 8 5 (27 F eb . 1945) t o Socony-Vacuum O i l Company, I n c .
n i t r o a l k a n e s may remove t h e n i t r o g r o u p , f o r m i n g , i n t h e p r o c e s s ,
n i t r i t e i o n .
113
S i n c e maximum r e s i s t a n c e was u s u a l l y o b t a i n e d a t t h e t i m e
w h i c h was e s t i m a t e d to be t h e t im e o f 10 h a l f - l i v e s (121), i t was
(121) See s e c t i o n e n t i t l e d D e t e r m i n a t i o n o f Time I n f i n i t y .
t a k e n a s . Those m e th o d s y i e l d e d v e r y c o n s i s t e n t s e c o n d - o r d e r
r a t e c o n s t a n t s .
M e t h o x i d e Io n C a t a l y s i s .— I n t h e s t u d i e s o f n e u t r a l i z a t i o n
o f t h e n i t r o compounds by m e t h o x i d e i o n i n m e t h a n o l , th e c o n d u c t i v i t y
c e l l s w e re h a n d l e d i n t h e s a n e manner a s b e f o r e . The c e l l u t i l i z e d
was s i m i l a r t o t h a t shown i n F i g u r e 5 .
A f t e r d r y i n g , t h e c e l l was p l a c e d i n an i c e - w a t e r b a t h a t
0 . 0 0 ° . An a l i q u o t ( 1 2 , 0 0 m l . ) o f t h e k i n e t i c s o l u t i o n ( 0 . 0 0 1 II
so d iu m m e t h o x i d e i n m e t h a n o l ) was t r a n s f e r r e d i n t o the c e l l w i t h
1 0 . 0 0 ml . and 2 . 0 0 ml . p i p e t t e s c h i l l e d t o - 1 0 ° . The s y s t e m was
b r o u g h t t o e q u i l i b r i u m a s b e f o r e .
The same p r o c e d u r e s u s e d i n t h e s t u d y o f h y d r o x i d e i o n
c a t a l y s i s were em ployed i n t h i s work e x c e p t t h a t a 0 .0200 m l . a l i
q u o t o f t h e n i t r o compound was i n j e c t e d i n t o t h e c e l l . T h e s e t e c h
n i q u e s y i e l d e d v e r y c o n s i s t e n t k i n e t i c d a t a .
E t h o x i d e I o n C a t a l y s i s .— The same t e c h n i q u e s , c o n c e n t r a t i o n s ,
a n d t e m p e r a t u r e s u s e d i n s t u d i e s o f m e t h o x i d e i o n c a t a l y s i s w ere
u s e d i n t h e s e i n v e s t i g a t i o n s . However , d e t e r m i n a t i o n of t h e v e l o c i t y
116
c o n s t a n t f o r n e u t r a l i z a t i o n o f n i t r o c y c l o h e p t a n e was made u s i n g
b o t h t h e t e c h n i q u e s employed i n m e t h o x i d e i o n c a t a l y s i s and t h e
t e c h n i q u e s em p lo y ed i n t h e g l y c o l a t e i o n c a t a l y s i s d e s c r i b e d i n
t h e n e x t s e c t i o n . T h i s work was done t o c o n f i r m t h a t t h e c a t a l y s t
i n t h e s e e x p e r i m e n t s w as , i n d e e d , e t h o x i d e i o n and n o t h y d r o x i d e
i o n t o any a p p r e c i a b l e e x t e n t .
G l y c o l a t e I o n C a t a l y s i s .— I n t h e s t u d i e s of n e u t r a l i z a t i o n
o f n i t r o compounds by g l y c o l a t e i o n , t h e c l e a n , s t o p p e r e d c o n
d u c t i v i t y c e l l s ( F i g u r e 6 ) we re r i g o r o u s l y d r i e d w i t h d r y a r g o n
w h i l e b e i n g f l a m e d . The a r g o n i n l e t was a h y p o d er m ic n e e d l e (16 g a . )
i n s e r t e d i n t o a r u b b e r serum cap w h ic h f i t t i g h t l y i n t h e mou th o f
t h e c e l l . The i n l e t n e e d l e e x t e n d e d a s c l o s e t o t h e b o t t o m o f t h e
c e l l a s p o s s i b l e . The e x h a u s t n e e d l e (13 g a . ) p r o t r u d e d j u s t
t h r o u g h t l ie s e p tu m i n t o t h e c e l l . T h i s a r r a n g e m e n t i n s u r e d maximum
f l o w o f g a s t h r o u g h t h e c e l l . The f l a m i n g an d p u r g i n g p r o c e s s was
c o n t i n u e d f o r 15 m i n u t e s , hlien t h e c e l l i iad c o o l e d , u n d e r a s l o w
s t r e a m o f a r g o n , i t was p l a c e d i n t h e i c e - w a t e r b a t h and a l l o w e d
s e v e r a l m i n u t e s t o r e a c h t h e r m a l e q u i l i b r i u m . Then an a l i q u o t
( 2 0 . 0 0 m l . ) o f t h e t h e r m o s t a t e d , k i n e t i c s o l u t i o n o f so d iu m g l y c o l a t e
( 0 . 0 0 1 N , l a e t h y l e n e g l y c o l ) was t r a n s f e r r e d t o th e c e l l .
W h i l e t h e k i n e t i c s o l u t i o n was b e i n g drawn i n t o t h e s y r i n g e ,
t h e e x h a u s t n e e d l e was removed from t h e s e r u m cap so t h e f l a s k w o u l d
n o t b e c o n t a m i n a t e d w i t h a i r . Wlii le t h e s o l u t i o n was b e i n g a d d e d t o
115
t h e c e l l , t h e e x h a u s t n e e d l e was l e f t i n t h e se rum cap t o i n s u r e
t h a t t h e i n t e r n a l c e l l p r e s s u r e e q u a l e d a t m o s p h e r i c p r e s s u r e . A f t e r
t h e l i q u i d h a d b e e n t r a n s f e r r e d t o t h e c e l l , t h e c e l l was p u r g e d w i t h
a r g o n by means o f t h e t h r e e - w a y v a l v e o n t h e s y r i n g e . I t was
e s s e n t i a l t h a t t h e i n t e r n a l p r e s s u r e o f t h e c e l l b e t h e same a s a t m o s
p h e r i c so t h a t t h e n i t r e compound c o u l d be i n j e c t e d e a s i l y i n t o t h e
k i n e t i c s o l u t i o n . The c e l l and i t s c o n t e n t s w e re a l l o w e d t o e q u i l i
b r a t e a s b e f o r e . At e q u i l i b r i u m , an a l i q u o t ( 0 . 0 4 - 0 . 0 8 m l . ) o f t h e
n i t r o compound was i n j e c t e d i n t o t h e c e l l w i t h a M i c r o m e t e r s y r i n g e .
The c e l l was re m o v e d f r o m th e b a t h , i n v e r t e d and s h a k e n w i t h a r a p i d
up and down m o t i o n an d i m m e d i a t e l y r e p l a c e d i n t h e b a t h . The s y s t e m
was a l l o w e d s u f f i c i e n t t i m e ( 0 . 5 - 0 . 7 5 m i n u t e s ) t o a g a i n e s t a b l i s h t h e
e l e c t r o d e - l i q u i d i n t e r f a c e b e f o r e z e r o t i m e was r e c o r d e d and r e s i s t a n c e
m e a s u r e m e n t s w e r e made a s d e s c r i b e d p r e v i o u s l y . The d a t a o b t a i n e d
w e re r e p r o d u c i b l e .
D e u t e r i u m E x c h a n g e . — I n o r d e r t o e s t a b l i s h r e l a t i v e r a t e s o f
p r o t o n r e m o v a l f r o m a r e p r e s e n t a t i v e n i t r o c y c l o p r o p a n e , d e u t e r i u m
ex c h a n g e s t u d i e s w e r e c o n d u c t e d on 2 - n i t r o p r o p a n e and t r a n s - 2 - e t h y l -
n i t r o c y c T o p r o p a n e u n d e r s i m i l a r c o n d i t i o n s i n t h e c o - s o l v e n t , d e u t e r i u m
o x i d e - d i m e t h y l f o r m a m i d e . R e f e r e n c e s o l u t i o n s , w h i c h d i d n o t c o n t a i n
a b a s i c c a t a l y s t , w e r e p r e p a r e d by m i x i n g i n a s m a l l s t o p p e r e d v i a l :
1 . 0 m l . 2 - n i t r o p r o p a n e (C om merc ia l S o l v e n t s C o r p o r a t i o n , p r e c i s i o n
r e c t i f i e d a s d e s c r i b e d ) , 1 . 0 m l . d e u t e r i u r a —o x i d e (Co lum bia O r g a n i c
116
d i m e t h y l f onnaûi ide ( J . T. Baker C h e m i c a l Company, r e a g e n t ) ; an d i n a
s e c o n d v i a l , 1 . 0 ml . t r a n s - 2 - e t h y l n i t r o c y c l o p r o p a n e (122), 1 . 0 m l .
d e u t e r i u m o x i d e and 3 . 0 ml . d i n i e t h y l f o r m a r a i d e .
(122) Sample p r e p a r e d i n t h i s l a b o r a t o r y by J . A s u n s k i s ; J . A s u n s k i s and II. S h e c h t e r , J . Org . Chem. , 33 , 1164 ( 1 9 6 8 ) .
N u c l e a r m a g n e t i c r e s o n a n c e s p e c t r a o f t h e r e f e r e n c e s o l u t i o n s
w e r e t a k e n t o i d e n t i f y p o s i t i o n s an d i n t e n s i t i e s of t h e s i g n a l s due
t o a c i d i c p r o t o n s o f t h e n i t r o compounds i n t h e s y s t e m s . The a c i d i c
p r o t o n o f t r a n s - 2 - e t h y l n i t r o c y c l o p r o p a n e a p p e a r s as an u n s y m m e t r i c a l
p e n t u p l e t a t a b o u t 4 . 1 ppm. ( 5 . 9 7 t a u ) . T h i s p e a k i s s h i f t e d
s l i g h t l y down f i e l d ( a b o u t 0 . 2 ppm.) i n t h e s o l u t i o n s w i t h d e u t e r i u m
o x i d e - d i m e t h y l f o r m a m i d e .
Tv;o k i n e t i c s o l u t i o n s w e re t h e n p r e p a r e d by m i x i n g i n a
s m a l l v i a l : 1 . 0 ml . 2 - n i t r o p r o p a n e , 1 . 0 ml . d e u t e r i u m o x i d e , 1 . 5
m l . d i m e t h y l f o r m a m i d e , and 0 . 1 5 m l . t r i e t h y l a m i n e ( M a th e s o n , C o l e
man, and B e l l , r e a g e n t ) ; and i n a s ec o n d v i a l : 1 . 0 m l . o f t r a n s -
2 - e t h y l n i t r o c y c l o p r o p a n e , 1 . 0 ml . d e u t e r i u m o x i d e , 3 . 0 ml . d i m e t h y l -
fo r ra a in ide , a n d 0 . 1 5 m l . t r i c t h y l a m i n e .
H. M. R. s p e c t r a showed t h a t 2 - n i t r o p r o p a n e h a d c o m p l e t e l y
e x c h a n g e d i t s a c i d i c p r o t i u m f o r d e u t e r i u m w i t h i n 40 m i n u t e s a t
room t e m p e r a t u r e , w h e r e a s t r a n s - 2 - e t h y l n i t r o c y c l o ? r o p a n e u n d e r w e n t
no a p p r e c i a b l e e x c h a n g e a f t e r two we eks u n d e r t h e same c o n d i t i o n s .
117
Th e t e c h n i q u e s h o u l d h a v e b e e n a b l e t o d e t e c t a n y d e u t e r i u m i n c o r p
o r a t i o n g r e a t e r t h a n a b o u t 10%.
D e u t e r i u m e x c h a n g e i n t o t h e m e t h i n e p o s i t i o n o f d i c y c l o -
p r o p y l k e t o n e was s t u d i e d . Two r e f e r e n c e s o l u t i o n s w e re p r e p a r e d :
0 . 5 m l . d i c y c l o p r o p y l k e t o n e (C o lum bia O r g a n i c C h e m i c a l s Company) i n
d e u t e r i u m - o x i d e - d i m e t h y l f o r m a m i d e ( 1 . 0 m l . - 1 . 8 0 m l . ) ; and 0 . 5 m l .
d i c y c l o p r o p y l k e t o n e i n t - b u t a n o l - d ^ ( 2 . 5 m l . ) ( 1 2 3 ) . The hT-ÎR
s p e c t r a o f t h e s e s o l u t i o n s w e re n o t c a l i b r a t e d w i t h D I S .
(1 23) t - B u t a n o l - d ^ was p r e p a r e d by s lo w a d d i t i o n o f D^O t o a n e x c e s s o f f r e s h l y s u b l i m e d p o t a s s i u m t - b u t o x i d e u n d e r an i n e r t a t m o s p h e r e . t - B u t a n o l - d was t h e n d i s t i l l e d a t r e d u c e d p r e s s u r e f rom t h e f l a s k . The i s o t o p i c p u r i t y o f t h e s o l v e n t wasd e t e r m i n e d by i t s NI-IR s p e c t r u m .
K i n e t i c s o l u t i o n s w e re p r e p a r e d u s i n g t h e same am o u n t s o f
m a t e r i a l , h o w e v e r , t h e y w e r e m a d e . 0 . 6 M i n s o d iu m d e u t e r o x i d e and
0 . 2 1 M i n p o t a s s i u m t - b u t o x i d e r e s p e c t i v e l y . NMR s p e c t r a o f t h e
s y s t e m c o n t a i n i n g d e u t e r o x i d e i o n w e re t a k e n o v e r a 5 day p e r i o d .
No i n c o r p o r a t i o n o f d e u t e r i u m i n t o t h e m e t h i n e p o s i t i o n o f d i c y c l o
p r o p y l k e t o n e c o u l d b e d e t e c t e d . NliR s p e c t r a o f t h e s y s t e m co n
t a i n i n g p o t a s s i u m t - b u t o x i d e w e re t a k e n o v e r a 20 d a y p e r i o d . No
i n c o r p o r a t i o n o f d e u t e r i u m c o u l d b e d e t e c t e d .
The c o m m e r c i a l r e a g e n t g r a d e m a t e r i a l s w e re u s e d w i t h o u t
f u r t h e r p u r i f i c a t i o n . The t r a n s - 2 - e t h y l n i t r o c y c l p r o p a n e was u s e d
a s o b t a i n e d . K i n e t i c s w e r e s t u d i e d a t room t e m p e r a t u r e .
118
T r l e t h y l a m l n e C a t a l y s i s .— I n t h e s t u d i e s o f n e u t r a l i z a t i o n o f
n i t r o compounds by t r i e t h y l a m i n e , t h e c o n d u c t i v i t y c e l l s w e r e p r e p a r e d
i n t h e m anner d e s c r i b e d i n t h e r e a c t i o n s w i t h h y d r o x i d e i o n .
The d r i e d , s t o p p e r e d c e l l , s i m i l a r t o t h e one i n F i g u r e 5 was
t h e r m o s t a t e d a t t h e d e s i r e d t e m p e r a t u r e and an a l i q u o t (an amou nt
s u f f i c i e n t t o c o v e r t h e e l e c t r o d e s , a b o u t 12 m l . ) o f t h e t h e r m o -
s t a t e d k i n e t i c s o l u t i o n ( 0 . 2 1 M t r i e t h y l a m i n e i n 50% by volume 1 , 2 -
d i m e t h o x y e t h a n e - w a t e r ) was t r a n s f e r r e d i n t o t h e c e l l w i t h a h y p o
d e r m i c s y r i n g e . The e n t i r e s y s t e m was a l l o w e d t o come t o e q u i l i b r i u m
a s b e f o r e .
When t h e s y s t e m h a d r e a c h e d e q u i l i b r i u m , a n a l i q u o t ( 3 . 4 m i c r o
l i t e r s ) o f t h e n e a t , k i n e t i c g r a d e , n i t r o com pound, a t room t e m p e r
a t u r e , was i n j e c t e d d i r e c t l y i n t o t h e c e l l w i t h a H am i l to n m i c r o l i t e r
s y r i n g e (701-N) and t h e c e l l c o n t e n t s w e r e s w i r l e d v i g o r o u s l y t o
i n s u r e c o m p l e t e s o l u t i o n o f t h e m o d e r a t e l y s o l u b l e n i t r o c y c l o a l k a n e .
A f t e r a b o u t 0 . 5 m i n u t e s , z e r o t i m e was r e c o r d e d on a l a p s e t i m e r a n d ,
i n t h e c a s e o f am in e c a t a l y s i s , t h e c o n d u c t i v i t y (1/R^) o f t h e c e l l
a t t h i s t i m e was r e c o r d e d . The i n c r e a s e i n c e l l c o n d u c t i v i t y was
f o l l o w e d a s a f u n c t i o n o f t i m e i n a m an n e r s i m i l a r t o t h a t f o r
f o l l o w i n g c h a n g e s i n r e s i s t a n c e i n a n i o n i c c a t a l y s i s s t u d i e s .
I n m ak in g t h e s e m e a s u r e m e n t s , t h e c o n d u c t i v i t y o f t h e c e l l
i n c r e a s e d s l i g h t l y u pon s t a n d i n g t o a v a l u e g r e a t e r t h a n t h e v a l u e
t a k e n ( a t 10 h a l f - l i v e s ) a s 1/R . T h i s s m a l l , c o n t i n u a l r i s e i n
119
c o n d u c t i v i t y was a t t r i b u t e d t o s u b s e q u e n t d e c o m p o s i t i o n o f t h e
n i t r o n a t e a n i o n i n t o more h i g h l y c o n d u c t i n g s p e c i e s a s m e n t i o n e d
b e f o r e .
D e t e r m i n a t i o n o f A p p a r e n t I o n i z a t i o n C o n s t a n t s . — B e f o r e e a c h
e . m . f . m e a s u r e m e n t , t h e g l a s s e l e c t r o d e was s t a n d a r d i z e d a g a i n s t
b o t h s t a n d a r d b u f f e r s o l u t i o n s ( 5 . 2 8 9 and 9 . 3 7 8 ) . The pH* v a l u e s
o f t h e s e f r e s h b u f f e r s w e r e i n t e r n a l l y c o n s i s t e n t t o w i t h i n 0 . 0 0 3
pH* u n i t s o f t h e a c c e p t e d v a l u e . A f t e r m e a s u r i n g t h e pH* o f t h e
t e s t s o l u t i o n , t h e g l a s s e l e c t r o d e was a g a i n c h e c k e d w i t h a s t a n d a r d
b u f f e r t o d e t e r m i n e i t s s t a b i l i t y .
I n m e a s u r i n g t h e a p p a r e n t i o n i z a t i o n c o n s t a n t f o r t h e
n i t r o c y c l o a l k a n e s , t e c h n i q u e s s i m i l a r t o t h o s e o f T u r n b u l l and
Maron (42) w e r e u s e d . The p H * 's w e r e m e a s u r e d on s o l u t i o n s made up
by a d d i t i o n o f an a l i q u o t ( 5 . 0 0 , 1 0 . 0 0 o r 1 5 . 0 0 m l . ) o f s t a n d a r d ,
c a r b o n a t e - f r e e , s o d i u m h y d r o x i d e ( a p p r o x i m a t e l y 0 . 0 0 4 in . t h e
s o l v e n t ) t o an a l i q u o t ( 2 0 . 0 0 m l . ) o f s t a n d a r d n i t r o compound ( a p p r o x
i m a t e l y 0 . 0 0 4 i n t h e s o l v e n t ) . E x c e p t f o r n i t r o c y c l o b u t a n e , e . m . f .
m e a s u r e m e n t s w e r e t a k e n 12 t o 24 h o u r s a f t e r e a c h s a m p l e was p r e
p a r e d s i n c e e q u i l i b r i u m was e s t a b l i s h e d v e r y s l o w l y . Long e q u i l i b r a t i o n
t i m e s w e r e a l s o n o t e d by T u r n b u l l an d Maron i n d e t e r m i n a t i o n s o f t h e
f o r 2 - n i t r o p r o p a n e .
E q u i l i b r i u m , i n a l l s y s t e m s e x c e p t n i t r o c y c l o b u t a n e , was
d e f i n e d a s t h e t i m e a t w h i c h t h e g l a s s e l e c t r o d e g a v e s t a b l e r e a d i n g s
120
o f e . m . f . d u r i n g a 10 t o 60 m i n u t e p e r i o d a n d v a l u e s c a l c u l a t e d
f rom 3 s i m i l a r m e a s u r e m e n t s a t e i t h e r 1/A o r 1 / 2 ( o r b o t h ) n e u t r a l
i z a t i o n p o i n t s w e r e r e p r o d u c i b l e t o w i t h i n - 10%. R e a d i n g s i n t h e
n i t r o c y c l o b u t a n e s y s t e m had t o b e made w i t h i n 26 m i n u t e s ( 1 / 4 o r
1 / 2 n e u t r a l i z a t i o n ) t o 100 m i n u t e s ( 3 / 4 n e u t r a l i z a t i o n ) o f m i x i n g .
The s y s t e m n e v e r r e a l l y a c h i e v e d e q u i l i b r i u m and showed e x t e n s i v e
c h a n g e a f t e r on e t o two d a y s .
I n a l l c a s e s , t h e t im e o f m e a s u r e m e n t o f e . m . f . was a t l e a s t
5 t i m e s t h a t c a l c u l a t e d f o r t h e r e a c t i o n t o t a k e p l a c e . T h i s c a l
c u l a t i o n was b a s e d on t h e s e c o n d - o r d e r r a t e c o n s t a n t s f o r n e u t r a l
i z a t i o n o f t h e r e s p e c t i v e n i t r o compounds i n 50% by volume 1 , 4 -
d i o x a n e - w a t e r a t 28° ( 1 9 ) .
The p o i n t o f e q u i l i b r i u m i n t h e s e s y s t e m s was open t o
q u e s t i o n . I n t h e w o r k by T u r n b u l l an d M a r o n , was d e t e r m i n e d
( p o t e n t i o m e t r i c a l l y ) by t i t r a t i o n o f an a l i q u o t o f a s t a n d a r d ,
a q u e o u s s o l u t i o n o f n i t r o compound w i t h i n c r e m e n t s o f s t a n d a r d so d iu m
h y d r o x i d e t o a p p r o x i m a t e l y 25% n e u t r a l i z a t i o n . I t was o b s e r v e d f o r
n i t r o m e t h a n e and n i t r o e t h a n e t h a t e q u i l i b r i u m ( a s m easu r ed b y t h e
c o n s t a n c y o f t h e e . m . f . r e a d i n g ) was a t t a i n e d r a p i d l y (1 m i n u t e and
5 m i n u t e s r e s p e c t i v e l y ) . P a r t i a l l y n e u t r a l i z e d s o l u t i o n s o f 2 - n i t r o
p r o p a n e r e q u i r e d 24 h o u r s t o a c h i e v e a c o n s t a n t e . m . f . r e a d i n g .
I n a l l c a l c u l a t i o n s o f K^, t h e c o n c e n t r a t i o n s o f t h e n i t r o
compound and i t s a n i o n were d e d u c ed f r om t h e am o u n ts of s o l u t i o n s o f
s t a n d a r d b a s e a n d n i t r o compound u s e d .
121
D e t e r m i n a t i o n o f t h e I o n i z a t i o n C o n s t a n t o f T r i e t h y l a m i n e . —
The i o n i z a t i o n c o n s t a n t , , o f t r i e t h y l a m i n e was d e t e r m i n e d i n 50%
by vo lume l , 2 - d i m e t h o % y e t h a n e - w a t e r u s i n g a g l a s s - c a l o m e l e l e c t r o d e
s y s t e m . The m e th o d o f s t a n d a r d i z a t i o n o f t h e g l a s s e l e c t r o d e i s
s i m i l a r t o t h a t o f R i t c h i e and U s c h o l d ( 1 2 4 ) , e x c e p t t h e g l a s s
e l e c t r o d e ( C o r n i n g 476022) was u n m o d i f i e d .
(124 ) C. D. R i t c h i e and R. E. U s c h o l d , J . Am. Chem. S o c . , 89 , 1721 ( 1 9 6 7 ) .
A s t a n d a r d s o l u t i o n of HCl ( a b o u t 0 . 0 0 1 K i n t h e s o l v e n t
s y s t e m ) was t i t r a t e d w i t h s t a n d a r d so d iu m h y d r o x i d e ( a b o u t 0 . 0 0 1 N
in t h e s o l v e n t s y s t e m ) . A p l o t o f - log[H"^] ( c a l c u l a t e d f rom
v o l u m e t r i c d a t a ) v e r s u s e . m . f . m e a s u r e d b%/ t h e g l a s s - c a l c m . e l e l e c
t r o d e s y s t e m g a v e a s t r a i g h t l i n e whose s l o p e was t h e t h e o r e t i c a l
59 - 2-mv w h e re 59-mv = 2 .3 0 3 RT/F , t h e t e m p e r a t u r e c o e f f i c i e n t o f
pH from t h e h e r n s t E q u a t i o n . ‘
The g l a s s e l e c t r o d e was c a l i b r a t e d a g a i n s t a s t a n d a r d s o l u t i o n
of HCl made up i n t h e s o l v e n t s y s t e m . I t h a s a l s o bee n shown (25)
t h a t t h e g l a s s e l e c t r o d e nay be c a l i b r a t e d f o r u s e i n a s i m i l a r
sy s t e m (50% by vo lum e 1 , 4 - d i o x a n e - w a t e r ) . v ; i th s t a n d a r d aque ous
b u f f e r s . Then a n a l i q u o t o f a s t a n d a r d s o l u t i o n o f t r i e t h y l a m i n e
made up i n t h e s o l v e n t was t r a n s f e r r e d t o t h e t h e r m o s t a t e d pH cup
and t i t r a t e d w i t h a l i q u o t s o f s t a n d a r d HCl s o l u t i o n . The c o n s t a n t
122
o f i o n i z a t i o n was c a l c u l a t e d f rom a m o u n t s o f s t a n d a r d s o l u t i o n o f
4 -
E t^ N , an d KCl u s e d . The c o n c e n t r a t i o n o f H was o b t a i n e d f r o m e . m . f ,
m e a s u r e m e n t s . The s t a n d a r d r e f e r e n c e s o l u t i o n was 0 . 0 0 1 0 0 N H C l .
M a t h e m a t i c a l A n a l y s i s o f K i n e t i c S v s t e m
N e u t r a l i z a t i o n o f Ac i d i c M i t r o Compoun ds . — The r e a c t i o n o f
a c i d i c n i t r o a l k a n e s w i t h a n i o n i c o r a m i n e b a s e s i s a b i m o l e c u l a r
p r o c e s s , f i r s t o r d e r i n n i t r o compound and f i r s t o r d e r i n b a s e .
I t may b e r e p r e s e n t e d by the g e n e r a l e q u a t i o n
HA + B -------- > a" + BH’’", (24 )
w here HA r e p r e s e n t s t h e a c i d i c n i t r o compound, B t h e b a s e , A t h e
- j -
n i t r o n a t e a n i o n and EH t'ne c o n j u g a t e a c i d o f t h e b a s e .
The r a t e o f t h i s r e a c t i o n i s e x p r e s s e d by
- d a / d t = d c / d t = k ^ a b , (25 )_ 4-
w h e r e a = [HA.], b = [ B] and c = [A ] = [BK ] a t t i m e , t , an d k ^ i s
t h e s e c o n d - o r d e r r a t e c o n s t a n t i n l i t e r s / m o l e - m i n u t e .
S i n c e t h e s e r e a c t i o n s were r u n u n d e r p s e u d o - f i r s t o r d e r
c o n d i t i o n s (HA > B o r B >> HA), t h e c o n c e n t r a t i o n o f t h e r e a c t a n t
i n e x c e s s r e m a i n e d e s s e n t i a l l y c o n s t a n t . I f HA w e re i n e x c e s s
( a n i o n i c c a t a l y s i s s y s t e m s ) , t h e n t h e r a t e o f d i s a p p e a r a n c e o f B i s
g i v e n by
- d b / d t = k ^ b , (2 6 )
whe re k.^ - k ^ a = p s e u d o - f i r s t o r d e r r a t e c o n s t a n t .
123
I n t e g r a t i o n o f E q u a t i o n 26 y i e l d s
l n ( b / b ) = k t , (2 7 )o
w h e r e b = t h e c o n c e n t r a t i o n o f B a t z e r o t i m e , t an d b = b - c .0 o o
T h e r e f o r e ,
l n [ l / ( b - c ) / b ] = k t . (2 8 )o o
The f r a c t i o n o f m a t e r i a l r e a c t e d a t t i m e , t , i s ( c / b ) and
c/b. - W (29)w h e r e X i s a m e a s u r a b l e p h y s i c a l p r o p e r t y o f t h e s y s t e m w h ic h v a r i e s
l i n e a r l y w i t h c o n c e n t r a t i o n o f a p a r t i c u l a r s p e c i e s (1 2 5 ) .
(1 25) A. A. F r o s t and R. G. P e a r s o n , " K i n e t i c s an d M e c h a n i s m " , J o h n W i l e y and S o n s , New Y o r k , 1953 , p . 2 9 .
I n t r o d u c i n g E q u a t i o n 29 i n t o E q u a t i o n 28 g i v e s
l n [ ( X < ^ - X ^ ) / X ^ - X)] = ' k t , (3 0 )
w h i c h r e a r r a n g e s t o
l n ( X ^ - X) = - k t + l n ( X ^ - X ^ ) . (31 )
F a s t r e a c t i o n s s u c h a s t h e s e b e i n g s t u d i e d a r e m o s t r e a d i l y
s t u d i e d by c o n d u c t o m e t r i c t e c h n i q u e s . T h e r e f o r e , i n t h i s i n v e s t i g a t i o n ,
X = 1 / R , R b e i n g t h e c e l l r e s i s t a n c e . S u b s t i t u t i n g 1 / R f o r X i n
E q u a t i o n 31 g i v e s
l n ( l / R ^ - 1 /R) = - k t + l n ( l / R ^ - 1 / R ^ ) . (32 )
A p l o t o f l o g ( 1 / R ^ - 1 / R) v e r s u s t i s a s t r a i g h t l i n e w i t h
s l o p e = - k ^ / 2 . 3 0 3 . The s e c o n d o r d e r r a t e c o n s t a n t , k ^ , e q u a l s
- 2 . 3 0 3 X s l o p e / b ^ .
124
T h i s m e thod o f a n a l y s i s ( p s e u d o - f i r s t o r d e r ) was s e l e c t e d
b e c a u s e t h e work o f F l a n a g a n (19) and t h a t o f W i l l i a m s (57) i n d i c a t e d
t h a t t h e r e a c t i o n b e t w e e n n i t r o c y c l o a l k a n e s and h y d r o x i d e i o n may
n o t b e g o i n g t o c o m p l e t i o n . Unde r p s e u d o - f i r s t o r d e r c o n d i t i o n s , t h e
l a r g e e x c e s s o f t h e n i t r o compound gave a d d i t i o n a l i n s u r a n c e o f t h e
c o m p l e t e n e s s o f r e a c t i o n and v e r i f i e d t h e r a t e c o n s t a n t s d e t e r m i n e d
by F l a n a g a n ( 1 9 ) . A l s o , t h i s method d o e s n o t r e q u i r e t h e d e t e r
m i n a t i o n o f R w h ic h i s n o t e a s i l v m e a s u r e d f o r f a s t r e a c t i o n s . I t o
i s a d v a n t a g e o u s b e c a u s e i f ( 1 / R ^ ^ - 1 /R) i s d i r e c t l y p r o p o r t i o n a l t o
t h e c o n c e n t r a t i o n o f t h e s p e c i e s i n t h e s y s t e m , i s i n d e p e n d e n t
o f t h e a b s o l u t e v a l u e o f t h e c o n d u c t a n c e , t h e p r o p o r t i o n a l i t y f a c t o r
b e t w e e n c o n d u c t a n c e a n d _ c o n c e n t r a t i o n and t h e m a g n i t u d e o f t h e
c o n d u c t a n c e c h a n g e .
F l a n a g a n (19) fo u n d t h a t i n t h e s y s t e m 50% by vo lume 1 , 4 -
d i o x a n o - w a t e r c o n d u c t a n c e d o es v a r y l i n e a r l y w i t h c o n c e n t r a t i o n of
s o d i u m h y d r o x i d e . Ko i n v e s t i g a t i o n of t h e r e l a t i o n b e t w e e n c o n d u c t a n c e
an d n i t r o n a t e a n i o n was made i n t h a t s t u d y . I t was a s s u m e d , h o w e v e r ,
t h a t a l i n e a r r e l a t i o n s o u l d a l s o h o l d f o r t h e n i t r o n a t e a n i o n i n t h e
same r a n g e o f c o n c e n t r a t i o n s . No i n v e s t i g a t i o n o f t h e l i n e a r i t y of
c o n d u c t a n c e w i t h c o n c e n t r a t i o n was made i n t h e p r e s e n t i n v e s t i g a t i o n .
H o w ev er , s i n c e t h e s o l v e n t s u s e d w e re o f r e a s o n a b l y h i g h d i e l e c t r i c
c o n s t a n t , and t l ie s y s t e m s r e a s o n a b l y d i l u t e , i t was a ssum ed t h a t t h e
i o n s wou ld b e h a v e i d e a l l y o r a t l e a s t t h a t t h e c o n d u c t a n c e w o u ld
125
v a r y i n a l i n e a r r e l a t i o n w i t h t h e c h a n g e o f c o n c e n t r a t i o n o f s p e c i e s
p r e s e n t .
I n t h e e x p e r i m e n t s i n v o l v i n g h y d r o x i d e i o n c a t a l y s i s t h e r a t i o
a / b was i n v e s t i g a t e d i n t h e r a n g e P.O < a / b < 10 00 . The r a t e o o o o ~
c o n s t a n t s w e re i n d e p e n d e n t o f t h e r a t i o . T h i s was n o t t r u e i n
g l y c o l a t e i o n c a t a l y s i s a t l e a s t f o r 2 - n i t r o p r o p a n e . With t h i s
m o l e c u l e i t was found t h a t was a f u n c t i o n o f t h e r a t i o , a ^ / b ^ , a t
low v a l u e s a nd i n d e p e n d e n t o f t h e r a t i o a t h i g h v a l u e s ( 5 0 0 / 1 t o
1 0 0 0 / 1 ) . T h i s s u g g e s t e d t h a t t h e r e a c t i o n was n o t g o i n g t o c o m p l e t i o n
a t low v a l u e s of a / b .o o
I n g e n e r a l , p l o t s o f l o g ( 1 / R ^ - 1 /R) v e r s u s t w e re good
s t r a i g h t l i n e s t o 90% c o m p l e t i o n a t t e s t i n g t h e v a l i d i t y o f t h e
e x p e r i m e n t a l t e c h n i q u e .
A c t i v a t i o n P a r a m e t e r s f o r Amine C a t a l y s i s . — The a c t i v a t i o n
p a r a m e t e r s f o r amine c a t a l y s i s w ere c a l c u l a t e d f rom t h e t h e rm o d y n a m ic
e q u a t i o n :
A S * /R AH*/RT: (
h 'k 2 = kT e e (33)
w h e r e k = B o l t z m a n n c o n s t a n t
h = P l a n c k c o n s t a n t
AS* = e n t r o p y o f a c t i v a t i o n
AH* = e n t h a l p y o f a c t i v a t i o n
X = K e l v i n t e m p e r a t u r e
R = Gaé c o n s t a n t
1 2 6
kgP l o t s w e r e made o f l o g — v e r s u s 1 / T . The s l o p e s o f t h e
s t r a i g h t l i n e s o b t a i n e d a r e - A H * / 2 . 3 0 3 R . AS* was c a l c u l a t e d f o r
e a c h o f t h e t h r e e t e m p e r a t u r e s f rom t h e e q u a t i o n s :{q
AS* = AH*/T - 2 .303 R l o g - 2 . 3 0 3 R l o g ^ (3 4 )
o rk?
AS* = AH*/T 4- 4 . 5 7 6 l o g ^ - 5 5 . 3 5 ( 3 5 )
and t h e a v e r a g e v a l u e t a k e n .
D e t e r m i n a t i o n o f Time I n f i n i t y . — I n d e t e r m i n i n g t h e r a t e s o f
n e u t r a l i z a t i o n o f n i t r o compounds by c o n d u c t o m e t r i c t e c h n i q u e s
e m p l o y i n g p s e u d o - f i r s t o r d e r c o n d i t i o n s , i t was e s s e n t i a l t h a t a n
a c c u r a t e v a l u e o f R ^ b e o b t a i n e d . H o w e v e r , i n t h e c a s e o f t r i e t h y l
am ine c a t a l y s i s , t h e r e s i s t a n c e o f a c e l l d i d n o t become c o n s t a n t
a f t e r a p e r i o d o f t i m e (10 h a l f - l i v e s ) more t h a n s u f f i c i e n t , f o r
t h e n e u t r a l i z a t i o n r e a c t i o n t o b e c o m p l e t e d . I n t h e c a s e s o f
c a t a l y s i s w i t h a n i o n i c s p e c i e s (OH , MeO , e t c . ) , t h e c e l l r e s i s t a n c e
wen t t h r o u g h a maximum, and t h i s maximum was t a k e n a s R ^ . I n
e i t h e r c a s e , t h e c h a n g i n g c e l l r e s i s t a n c e was s u p p o s e d l y due t o s u b
s e q u e n t d e c o m p o s i t i o n o f t h e n i t r o n a t e i o n t o y i e l d n i t r i t e i o n s a l t s
o f o r g a n i c a c i d s ( 9 1 ) . T h e r e f o r e , i t was n e c e s s a r y t o e s t a b l i s h a
m e thod o f e s t i m a t i n g i n f i n i t e t i m e an d h e n c e , i n f i n i t e r e s i s t a n c e i n
t h e s e s y s t e m s .
C a l c u l a t i o n s show t h a t a t a t i m e o f 10 h a l f - l i v e s i n a p s e u d o -
f i r s t p r o c e s s , t h e r e a c t i o n i s 99.9% c o m p l e t e . The r e s i s t a n c e a t 10
127
h a l f - l i v e s c a n , t h e r e f o r e , be c o n s i d e r e d i n f i n i t e r e s i s t a n c e . The
t i m e a t 10 h a l f - l i v e s was c a l c u l a t e d by a s e l f - c o n s i s t e n t m e t h o d f rom
t h e k i n e t i c d a t a . T h i s m ethod i n v o l v e d r e p e a t e d e v a l u a t i o n o f t h e
e x p r e s s i o n ;
/ ( 1 / R ^ - 1 / R ) / = ( 1 / R ) ^ / 2 ’ ( 3 6 )
2
w h e r e 1 /R = r e s i s t a n c e o f t h e c e l l a t z e r o t i m e ,o
1 /R = r e s i s t a n c e o f t h e c e l l a t an y t i m e , t ,
( 1 / R ) ^ = r e s i s t a n c e o f t h e c e l l a t I ' h a l f - l i f ec a l c u l a t e d f r o m d a t a a t t i m e , t ,
an d / ( 1 / R - 1 / R ) / = a b s o l u t e v a l u e o f d i f f e r e n c e s o f c e l lc o n d u c t a n c e a t t i m e t and t .o
S u c c e s s i v e v a l u e s o f c e l l r e s i s t a n c e , m e a s u r e d a t s p e c i f i c t i m e s ( t )
d u r i n g t h e r e a c t i o n , a r e u s ed t o e v a l u a t e t h e e x p r e s s i o n . As t h e
r e a c t i o n a p p r o a c h e s c o m p l e t i o n , t h e v a l u e ( 1 / R ) ^ y 2 w i l l u s u a l l y b e
f o u n d t o l i e b e t w e e n two r e c o r d e d r e s i s t a n c e s an d h e n c e b e t w e e n two
r e c o r d e d t i m e s . The l a r g e r v a l u e o f t h e r e c o r d e d t im e was t a k e n
a s t h e u p p e r l i m i t o f 1 h a l f - l i f e . The c e l l r e s i s t a n c e a t i n f i n i t e
t i m e was m e a s u r e d a t o r b e f o r e t h e t i m e c o r r e s p o n d i n g t o t h e u p p e r
l i m i t o f (10 X 1 h a l f - l i f e ) .
T h i s t e c h n i q u e , a s u s e d t o e s t i m a t e t i m e i n f i n i t y , g a v e v e r y
c o n s i s t e n t v a l u e s f o r t h e s e c o n d - o r d e r r a t e c o n s t a n t s ( k ^ ) d e t e r m i n e d
i n t h e t r i e t h y l a m i n e c a t a l y s i s s t u d i e s . I t a l s o showed t h a t t h e
maximum r e s i s t a n c e o f t h e c e l l s i n a n i o n i c c a t a l y s i s e x p e r i m e n t s was
v e r y n e a r l y e q u a l t o R ^ .
APPENDIX I
1 2 8
129
TABLE 14
RATE CONSTANTS FOR NEUTRALIZATION OF 2-NITROPROPANE BY SODIUi'I HYDROXIDE IN 50% BY VOLUNE 1,2-DIMETHOXYETHANE-UATER
AT 0 . 0 0 ° AS A FUNCTION OF IN IT IA L CONCENTRATION OF 2-NITROPROPANE
[R„CHNO„] X 10^ ^ z o
[NaOK] X 10^ k ( m i n . ” ^)o 1
k ^ C l . / m . - m i n . )
2 . 2 2 1 . 0 0 . 0 2 1 0 9 . 4 64 . 6 4 1 . 0 0 . 0 4 8 4 1 0 . 46 . 9 6 1 . 0 0 . 0 6 8 3 9 . 8 19 . 2 8 1 . 0 0 . 0 9 3 8 1 0 . 1
■ 2( a v g . ) = 1 0 . 0 - 0 . 3 l . / r a . - r a i n .
TABLE 15
RATE CONSTANTS FOR NEUTRALIZATION OF2-NITROPROPANE BY SQDIUN HYDROXIDE IN
50% BY VOLUME 1 , 2-DIMETllOXYETHANE-WATER AT 0 .0 0 °
130
[RgCHNOglo X 10^ [NaOli]^ X 10^ k ^ ( m l n . “ ^) k 2 ( l . / m . - m i n . )
4 .6 4 9 .5 5 0 .0 5 2 1 1 1 .24 .6 4 9 .5 5 0 .4 0 8 4 1 0 .44 .6 4 9 .5 5 0 .0 5 0 8 1 0 .94 .6 4 9 .5 5 0 .5 6 3 1 1 .6
^2( a v g . ) = 1 0 .4 - 0 .6 1 . / r a . - m in .
TABLE 16
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOBUTANE BY SODIUM HYDROXIDE IN
50% BY VOLUME 1 , 2-DIMEIllOXYETHANE-WATER AT 0,.0 0 °
[RgCHNO,], X 10^ [NaOH]^ X 10^ k ^ ( n i in .~ ^ ) k ^ ( 1 . / n . - m i n . )
4 .9 6 9 .5 5 0 .7 0 7 1424 .9 6 9 .5 5 0 .7 0 7 1424 .9 6 9 .5 5 0 .7 1 3 1454 .9 6 9 .5 5 0 .7 0 8 143
^2 ( a v g . ) = 143 - 1 1 . / m . - m i n .
131
TABLE 17
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOPENTANE BY SODIUIl HYDROXIDE IN
50% BY VOLUME 1 , 2-DIMETHOXYETHANE-WATER AT 0 .0 0 °
[R^CHNOglo X 10^ [NaOH] X 10^ k , ( m i n . " ^ )O -L k 2 ( l . / m . - m i n . )
3 .8 6 9 .5 5 0 .1 6 6 4 3 . 03 .8 6 9 .5 5 0 . 1 6 8 4 3 .53 . 8 6 9 .5 5 0 .1 6 2 4 1 . 23 .8 6 9 .5 5 0 .1 5 4 3 9 .9
^2 ( a v g . ) = 4 1 .9 - 1 . 3 1 . / m . - m i n .
TABLE 18
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOHEXANE BY SODIUM HYDROXIDE IN
502; BY VOLUME I,2-DIMETH0XYETILAi;E-WATER AT 0 .0 0 °
[RgCHNOgjg X 10^ [NaOH]^ X 10^ k ^ ( m i n . “ ^) k ^ ^ l . / m . - m i n . )
3 .3 9 9 .5 5 0 .0 2 7 2 8 .0 23 .3 9 9 .5 5 0 .0 2 7 6 8 .1 43 .3 9 1 0 .1 0 .0 2 8 6 8 . 4 43 .3 9 1 0 .1 0 .0 2 6 6 7 .8 5
^2 ( a v g . ) = 8 .1 1 - 0 . 1 8 1 . / m . - m in .
1 3 2
TABLE 19
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOHEPTAiNE BY SGDIUI-I HYDROXIDE IN
50% BY VOLUME 1 , 2-DIMETHOXYETHANE-WATER AT 0 .0 0 '
[RgCHNOg]^ X 10^ [NaOII]^ X lo'^ k ^ C m in ." ^ ) k - ^ / l . / m . - m i n . )
3 .0 4 1 .0 1 0 .0 7 4 8 2 4 .63 .0 4 1 .0 1 0 .0 7 1 7 2 3 .63 .0 4 1 .0 1 0 .0 7 3 6 2 4 .23 .0 4 1 .0 1 0 .0 7 4 9 2 4 .6
( a v g . ) = 2 4 .2 - 0 . 4 1 . / m . - m i n .
TABLE 20
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOOCTANE BY SODIUM HYDROXIDE IN
50% BY VOLUME 1 , 2-DIMETHOXYETHANE-WATER AT 0 .0 0 °
[RgCHNOgl^ X 10^ [NaOH] X lo'^ k , ( r a i n . " ^ ) 0 1
k g ^ l . / m . - m i n . )
2 .7 6 1 .0 1 0 .0 5 1 8 1 8 .82 .7 6 1 .0 1 0 .0 5 2 3 1 9 .02 .7 6 1 .0 1 0 .0 5 2 8 1 9 .12 .7 6 1 .0 1 0 .0 5 0 0 1 8 .1
k^ ( a v g . ) = 1 8 .8 - 0 . 0 3 1 . / m . - m i n .
133
TABLE 21
RATE CONSTANTS FOR NEUTRALIZATION OF2-NITROPROPANE BY SODILÎ-I METHOXIDE IN
MET1IAÎJ0L AT 0 .0 0 °
[RgCHNO ] X 10^ [NaOMe]^ X 10^ k ^ ( r a i n . " ^ ) k g X l . / m . - m i n . )
1 .8 5 1 .0 0 . 0 2 5 3 1 .3 61 .8 6 1 .0 0 .0 2 3 5 1 .2 71 .8 6 1 .0 0 .0 3 1 3 1 .6 91 .8 6 1 .0 0 .0 2 8 2 1 .5 2
( a v g . ) = 1 .4 6 - 0 .1 0 1 . / m . - m i n .
TABLE 22
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOBUTANE BY SODIUM METHOXIDE IN
METHANOL AT 0 .0 0 °
[RgCHNOg]^ X 10^ [NaOMe] X 10^ k , ( m i n . “ ^) 0 1
k ^ ( l . / m . - m i n . )
1 .9 8 1 .0 0 . 4 9 8 2 5 .21 .9 8 1 .0 0 . 5 0 3 2 5 .41 .9 8 1 .0 0 . 5 1 3 2 5 .91 .9 8 1 .0 0 . 5 4 8 2 7 .6
“ a( a v g . ) = 2 6 .0 - 0 . 8 1 . / m . - m i n .
134
TABLE 23
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOPENTANE BY SODIUM METHOXIDE IN
METHANOL AT 0 .0 0 °
[R^CHNO^]^ X 10^ [NaOMe] X 10^ k . ( r a i n . " ^ ) k^ o 1 2
( 1 . / m . - m i n . )
1 .5 4 1 .0 0 .1 1 6 7 .5 21 .5 4 1 . 0 0 .1 1 7 7 .5 71 .5 4 1 .0 0 .1 1 6 7 .5 11 .5 4 1 .0 0 .1 2 4 8 .0 8
• ^ 2 ( a v g . ) = 7 .6 7 - 0 .2 0 1 . / m . - m i n .
TABLE 24
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOHEXAI\[E BY SODIUM METHOXIDE IN
METHANOL AT 0 .0 0 °
[R„CHiNO„] i. / o X 10^ [NaOMe] X 10^ k ( m in .~ ^ ) k„ o 1 z
( l . / m . - m i n . )
1 .3 6 1 . 0 0 .0 2 6 8 1 .9 71 .3 6 1 .0 0 .0 3 0 2 2 .2 21 .3 6 1 .0 0 .0 2 9 4 2 .1 61 .3 6 1 . 0 0 .0 2 9 6 2 .1 8
k2 ( a v g . ) = 2 .1 3 - 0 . 0 8 1 . / m . - m i n .
135
TABLE 25
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOHEPTANE BY SODIUN METHOXIDE IN
METHANOL AT 0<.00°
[R^CHNOg]^ X i q 2 [NaOMe] X 10^ k ^ ( r a i n . “ ^) k ^ ( l . / m . - m i n . )
1 .2 2 1 . 0 0 .0 6 4 5 5 .3 01 .2 2 1 . 0 0 .0 6 8 2 5 .5 91 .2 2 1 . 0 0 .0 6 8 2 5 .5 91 .2 2 1 . 0 0 .0 6 7 7 5 .5 6
^2 ( a v g . ) = 5 .5 1 - 0 .0 5 l . / m . - m i n .
TABLE 26
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOOCTANE BY SODIUM METHOXIDE IN
METHANOL AT 0 .0 0 °
[RgCHNOg]^ X 10^ [NaOMe] X 10^ k , ( m i n . “ ^)O -L
k g ( l . / m . - m i n . )
1 .1 0 1 . 0 0 .0 4 6 3 4 .1 91 . 1 0 1 . 0 0 .0 4 7 0 4 .2 51 . 1 0 1 . 0 0 .0 4 6 8 4 .2 31 . 1 0 1 .0 0 .0 5 4 0 4 .9 1
^2( a v g . ) = 4 .4 0 - 0 .2 6 l . / m . - m i n .
136
TABLE 27
RATE CONSTANTS FOR NEUTRALIZATION OF2-NITROPROPANE BY SODIUÎI ETIIOXIDE IN
ETI-IANOL AT 0 .0 0 °
[R CIINO ]2. / 0
X 10^ [NaOEt] X 10^ k , ( m i n . “ ^)O 1
k ^ ( l . / m . - m i n . )
1 .8 6 1 .0 0 . 5 9 4 3 1 .91 .8 6 1 .0 0 .6 3 9 3 4 .41 .8 6 1 .0 0 . 5 8 3 3 1 .31 .8 6 1 . 0 0 .6 3 2 3 4 .0
( a v g . ) = 3 2 .9 - 1 . 3 l . / m . - m i n .
TABLE 28
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOBUTANE BY SODIUFÏ ETUOXIDE IN
ETtiANOL AT 0 .0 0 °
[RgCHNOg]^ X 102 [NaOEt] X 10^ k f r n i n . " ^ ) o 1
k g ( l . / m . - m i n . )
1 .9 8 1 . 0 Im m e a su ra b ly f a s t
k ^ ( e s t . ) = 2 9 1 l . / m . - m i n .
137
TABLE 29
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOPENTANE BY SODIUN ETHOXIÜE IN
ETHANOL AT 0.,00°
[R^CHNOg]^ X 10^ [NaOEt]^ X 10^ k ^ ( m in . k g ( l . / m . - m i n . )
1 .5 4 1 .0 1 .9 6 1271 .3 4 1 .0 2 .0 8 1351 .5 4 1 .0 2 .0 4 1331 .5 4 1 .0 1 .9 0 144
kg ( a v g ' ) = 135 - 5 1 . / m . - m i n .
TABLE 30
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOHEXANE BY SODIUN ETKOXIDE IN
ETHANOL AT 0 . 00°
[R_CHNO_]Z Z o X 10^ [NaOEt] X 10^ o
k^Crain. k g ( l . / m . - m i n .
1 .3 5 1 .0 0 .3 5 2 2 5 .81 .3 6 1 .0 0 .3 2 9 2 4 .21 .3 6 1 .0 0 .3 1 3 2 3 .01 .3 6 1 .0 0 .3 4 3 2 4 .5
( a v g . ) = 2 4 .5 - 01.9 l . / m . - m i n .
138
TABLE 31
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOHEPTANE BY SODIUN ETHOXIDE IN
ETHANOL AT 0 .0 0 °
[R2CHN02]Q X 10^ [NaOEt] X 10^ 0
k ^ C l . / m . - m i n . )
1 .2 2 1 .0 0 .9 2 1 7 5 .71 .2 2 1 .0 1 .0 0 8 2 .21 .2 2 1 .0 0 .9 4 2 7 7 .51 .2 2 1 .0 0 .9 9 2 8 1 .6
" 2( a v g . ) = 7 9 .2 - 2 . 6 l . / m . - m i n .
TABLE 32
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOOCTANE BY SODIU)! ETHOXIDE IN
ETHANOL AT 0 .0 0 °
[R-CHNO,] X 10^ i. ^ 0
[NaOEt] X 10^ 0
k ^ ( m in .~ ^ ) k ^ ( l . / m . - m i n . )
1 .1 0 1 .0 0 .6 3 0 5 7 .31 .1 0 1 .0 0 .6 5 1 5 9 . 21 .1 0 1 . 0 0 .6 2 5 5 6 .81 .1 0 1 . 0 0 .6 5 2 5 9 .3
k ( a v g . ) = 5 8 .2 - 1 . 1 l . / m . - m i n .
139
TABLE 33
RATE CONSTANTS FOR NEUTRALIZATION OF 2-NITROPROPANE BY SODIUÎ'I GLYCOLATE IN ETHYLENE GLYCOL AT 0 .0 0 ° AS A FUNCTION
OF THE INITIAL CONCENTRATION OF 2-NITROPROPANE
[R CHNOg]^ X 10% [NaO(CH2)20H]g X 10^ k 2 ( l . / m . - m i n . )
2 .2 2 10 0 .0 1 5 4 0 .6 9 02 .0 6 10 0 .0 1 2 9 0 .6 2 64 .4 6 10 0 .0 6 3 0 1 .4 14 .1 2 10 0 .0 4 7 8 1 .1 64 .4 6 5 .0 0 .0 8 1 8 1 .8 34 .4 6 2 .0 0 .0 7 2 3 1 .6 24 . 1 2 2 .0 0 .0 2 8 1 0 .6 8 24 .4 6 2 .0 0 .1 0 7 5 2 .4 24 .4 6 30 0 .0 3 4 8 0 .7 8 1
1 1 .1 10 0 .1 5 7 1 .4 21 1 .1 10 0 .1 9 6 1 .7 7
4 .4 6 1 .0 0 .1 0 4 2 .3 41 1 .1 1 . 0 0 .2 5 8 2 .3 21 1 . 1 1 . 0 0 .2 6 6 2 .4 0
TABLE 34
RATE CONSTANTS FOR NEUTRALIZATION OF2-NITROPROPANE BY SODIUM GLYCOLATE IN
ETHYLENE GLYCOL AT 0 .00°
140
[RgCHNOg]^ X 10^ [NaO(CH„)„OH] X 10* k , ( m i n . " ^ )Z Z O 1 k 2 l . / m . - m i n .
4 .4 6 2 . 0 0 .1 0 8 2 .4 24 .4 6 1 . 0 0 .1 0 4 2 .3 4
1 1 .1 1 . 0 0 .2 5 8 2 .3 21 1 . 1 1 . 0 0 .2 6 6 2 .4 0
^2( a v g . ) = 2 .3 7 - 0 .0 4 l . / m . - m i n .
TABLE 35
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOBUTANE BY SOÜIUîI GLYCOLATE IN
ETHYLENE GLYCOL AT 0 .0 0 °
[RgCHNOgjg X 10^ [Na0(CH2)20H] X 10^ k ^ ( m i n . “ ^ ) k ^ l . / m . - m i n .
2 .1 4 3 . 0 0 .3 8 3 1 7 .92 .1 4 3 . 0 0 .4 4 0 2 0 .62 .1 4 3 . 0 0 .3 7 7 1 7 .62 .1 4 3 . 0 0 .4 0 4 1 8 .9
k ( a v g . ) = 1 8 . 8 - 0 .9 l . / m . - m i n .2
141
TABLE 36
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOPENTANE BY SODIUI-I GLYCOLATE IN
ETHYLENE GLYCOL AT 0 .00°
[R2CHN02]q X 10^ [NaO(CIl2)20H]^ X 10^ k ^ l . / m . - m i n .
3 .7 0 3 .0 0 .2 8 5 7 .7 03 .7 0 3 .0 0 .2 8 6 7 .7 33 .7 0 3 .0 0 .2 6 3 7 .1 13 .7 0 3 .0 0 .3 2 3 7 .9 7
^2( a v g . ) = 7 .6 3 - 0 .2 6 l . / m . - m i n .
TABLE 37
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOHEXANE BY SODIUN GLYCOLATE IN
ETHYLENE GLYCOL AT 0 .0 0 °
[RgCHNOglo X 10% [NaO(CH2)20H] X 10^ k ^ ( m i n . “ ^) k ^ l . / m . - m i n .
8 .0 1 1 .0 0 .1 1 0 1 .3 78 .0 1 1 .0 0 .1 1 6 1 .4 58 .0 1 1 .0 0 .1 1 1 1 .3 98 .0 1 1 .0 0 .1 0 9 1 .3 6
( a v g . ) = 1 .3 9 - 0 .0 3 l . / m . - m i n .
142
TABLE 38
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOHEPTANE BY 'SODIUI-I GLYCOLATE
IN ETHYLENE GLYCOL AT 0 .0 0 °
[RCHNO ]Z Z o
X 10^ [NaO(CH2)20H] X 10^ k ^ ( m i n . “ ^ ) k ^ l . / m . - m i n .
7 .3 1 3 .0 0 .3 5 4 4 .8 47 .3 1 3 .0 0 .4 2 8 5 .8 53 .6 6 3 .0 0 .2 0 6 5 .6 33 .6 6 3 . 0 0 .1 9 6 5 .4 1
kg ( a v g . ) = 5 .4 3 - 0 . 3 1 l . / m . - m i n .
TABLE 39
RATE CONSTANTS FOR NEUTRALIZATION OFNITROCYCLOOCTANE BY SODIUI-I GLYCOLATE IN
ETHYLENE GLYCOL AT 0 . 0 0 °
[R„CHN0J ^ Z o
X 10^ [NaOCCH^igOHj^ X 10^ k j_ (m ln .“ ^) k g l . / m . - m i n .
2 .6 5 3 .0 0 .0 7 8 7 2 .9 76 .6 3 3 .0 0 .1 9 2 2 .9 06 .6 3 3 .0 0 .1 8 1 2 . 7 36 .6 3 3 .0 0 .1 6 8 2 .5 5
k ( a v g . ) = 2 .7 9 - 0 .1 5 l . / m . - m i n .2
143
TABLE 40
REPRESENTATIVE DATA FOR NEUTRALIZATION OF 2-NITROPROPANE BYSODIUM HYDROXIDE IN 50% BY VOLUME 1 , 2-DIHETHOXYETHANE-WATER
AT 0 .0 0 “ AS A FUNCTION OF INITIAL CONCENTRATION OF 2-NITROPROPANE
Run 6 0 -IV Temp. = 0 . 0 0 “
2 - N i t r o p r o p a n e NaOH = 0 .0 0 0 1 0 1
= 0 .0 0 2 2 2 MN
R X 1 0 -4 Time(Ohms) Log [ ( 1 / R - 1 /R ^ ^ )1 0 ^ ] (M in . )
2 .3 1 1 8 E q u i l i b r i u m2 .3 8 0 0 2 .0 2 6 1 0 .0 02 .5 5 3 0 1 .8 9 0 4 1 0 .0 62 .6 6 0 7 1 .7 9 1 2 2 0 .0 22 .7 4 6 9 1 .6 9 9 3 3 0 .0 32 .8 9 3 5 1 .4 9 9 6 5 2 .6 82 .9 7 4 0 1 .3 4 7 1 7 0 .0 13 .0 4 1 7 1 .1 6 8 8 9 0 .0 03 .0 8 9 8 0 .9 8 3 6 1 1 0 .0 03 .1 2 3 6 0 .7 8 7 5 1 3 0 .03 .1 7 2 5 0 .0 7 9 2 1903 .1 8 4 6 262 (oo;
S lo p e = 0 . 00914- 1
m in . k_ = 0 . 0 2 1 0 /0 .0 0 2 2 2 = 9 . 4 6 l . / m . - m i n .
P lo t o f k in e t i c run 60-IV shown in F igure 7 .
2000 '
.500
? 1 . 0 0 0
94%
0.5001__0.00 25 .0 50.0 75 .0 100.0 125.0
Ti me ( mi n. )F igu re 7 . -o
145
TABLE 41
REPRESENTATIVE DATA FOR NEUTRALIZATION OF 2-NITROPROPANE BYSODIUM HYDROXIDE IN 50% BY VOLUME 1 , 2-DIMETiIOXYETHANE-WATER
AT 0 .0 0 ° AS A FUNCTION OF INITIAL CONCENTRATION OF 2-NITROPROPANE
Run 61 -IV Temp. = 0 . 00°
2 - N i t r o p r o p a n e NaOH = 0 .000101
= 0.00696 MN
- 4R X 10 (Ohms) Log [ ( 1 /R - 1 /R ) i c / ]
oo
Time(M in . )
2 .4 2 32 .5 5 0 0
E q u i l i b r i u m1 .8 6 7 2 0 . 0 0
2 .7 1 0 0 1 .7 0 3 3 5 . 0 12 .8 2 2 0 1 .5 5 4 6 1 0 .0 12 .9 0 4 0 1 .4 1 2 5 1 5 .0 62 .9 6 5 0 1 .2 7 3 5 2 0 .0 13 .0 4 7 2 0 .9 8 5 4 3 0 .0 13 .0 9 3 8 0 .6 7 4 9 4 0 . 0 03 .1 1 9 9 0 .3 0 5 4 5 0 .0 43 .1 3 9 7 . 82 (oo:
S lo p e = 0 . 0296 m in . ^ kg = 0 . 0 6 8 3 /0 .0 0 6 9 6 = 9 .8 1 l . / m . - m i n .
P l o t o f k i n e t i c r u n 61 -IV shown i n F i g u r e 8 .
2.000
1.500
.000
0.500
97%
20.00.00 10.0 30.0 4 0 .0 50.0 MF ig u re 8 . Time ( min.) ON
147
TABLE 42
REPRESENTATIVE DATA FOR NEUTRALIZATION OF NITROCYCLOBUTAI'JE BY SODIUî-I HYDROXIDE IN
50% BY VOLUZ-IE 1,2-DIMETHOXYETHANE-WATER AT 0 . 0 0 '
Run 2 8 -IV N i t r o c y c l o b u t a n e = 0 .0 0 4 9 6 MTemp. = 0 . 00° NaOH = 0 .0 0 0 0 9 5 5 N
R X 1 0 "^ Time(Ohms) Log [ ( 1 /R - 1 / R ^ ^ ) 1 0 ' ] (M in . )
2 .6 4 1 2 E q u i l i b r i u m3 .0 0 0 0 1 .8 9 3 4 0 . 0 03 .2 6 0 0 1 .7 5 3 3 0 . 4 83 .5 2 0 0 1 .5 3 1 5 1 . 1 33 .6 3 0 0 1 .4 0 4 7 1 . 5 23 .7 3 4 0 1 .2 4 8 5 2 . 0 03 .8 2 0 0 1 .0 6 7 8 2 . 5 73 .8 7 0 0 0 .9 1 9 6 3 .0 43 .9 0 6 0 0 .7 7 3 0 3 . 5 03 .9 3 3 0 0 .6 2 0 1 4 . 0 03 .9 5 5 0 0 .4 3 9 3 4 . 5 73 .9 6 7 0 0 .0 7 5 6 5 . 0 13 .9 9 4 6 7 .5 03 .9 9 8 5 1 0 . 0 0 (o o )3 .9 9 3 7
— 1 0 .7 2 116
S lo p e = 0 . 313 m in . k = -------------- = 145 l . / m . , -m in .2 0 .0 0 4 9 6
P l o t o f k i n e t i c r u n 2 8 - I V shown i n F i g u r e 9 .
2.000
.5 0 0
1.000
o>
0 .5 0 096%
1.00 2.00 3 .0 0 4 .0 0 5 .0 0F igu re 9, T i m e ( mi n J
4N00
149
TABLE 43
REPRESENTATIVE DATA FOR NEUTRALIZATION OF NITROCYCLOPENTANE BY SODIUM METHOXIDE
IN METHANOL A’T 0 .0 0 °
Run 8 2 -IV N i t r o c y c l o p e n t a n e = 0 .0 1 5 4 MTemp. = 0 .0 0 ° NaOMe = 0 .0 0 0 1 0 N
. ^ - 4R X 10 7 Time(Ohms) Log [ ( 1 / R - 1 / R ^ ^ ) 1 0 ' ] ( M in . )
1 .4 6 0 0 2 .0 1 0 3 0 .0 01 .5 2 3 0 1 .8 6 9 4 2 .5 41 .5 6 9 0 1 .7 3 8 5 5 .0 41 .6 0 3 8 1 .6 1 2 2 7 .5 11 .6 3 0 7 1 .4 8 6 4 1 0 .0 01 .6 6 7 2 1 .2 3 6 3 1 5 .0 01 .6 8 9 2 0 .9 7 4 0 2 0 .2 41 .7 0 0 7 0 .7 3 3 2 2 5 .0 01 .7 0 7 6 0 .4 8 2 9 3 0 .0 01 .7 1 6 5 74 (oo:
S lo p e = 0 .0 5 0 6 m in. -1 = 0 . 1 1 7 / 0 . 0 1 5 4 = 7 .5 7 l . / m . - m i n .
Plot of kinetic run 82-IV shown in Figure 10.
2.000
'o 1.500
o> 1.000
0 .5 0 0 97%
10.0 20.00.00 30.0F igu re 10.
Time ( min.) UlO
TABLE 44
REPRESENTATIVE DATA FOR NEUTRALIZATION OF NITROCYCLOHEXANE BY s'ODIUII ETHOXIDE
IN ETHANOL AT 0 .0 0 °
151
Run 1 0 7 - IV N i t r o c y c l o h e x a n e = 0 .0 1 3 6 MTemp. = 0 .0 0 ° NaOEt = 0 .0 0 1 0 N
R X 1 0 -4 Time(Ohms) Log [ ( 1 / R - 1 /R ^ ^ )1 0 ^ ] (M in .)
2 .1 5 8 6 E q u i l i b r i u m2 .2 0 0 0 , , 1 , 4 8 3 3 0 .0 02 .2 4 0 0 1 .3 4 8 7 1 .0 42 .2 7 0 0 1 .2 1 5 4 2 .0 12 .2 9 3 0 1 .0 7 9 2 3 .0 02 .3 1 1 0 0 .9 3 4 5 4 .0 42 .3 2 4 0 0 .7 9 1 0 5 .0 82 .3 3 9 6 0 .5 1 9 8 7 .0 32 .3 5 7 9 20 (oo
1S lo p e = 0 .1 3 6 m in . k = 0 . 0 3 1 3 / 0 . 0 1 3 6 = 23. 0 l . / m . - m i n .
P l o t o f k i n e t i c r u n 1 0 7 -IV shown i n F i g u r e 1 1 .
1.500
8 1.000
o»89%0.500
0.00 2.50 5.00 7 . 50 M
Figure 11. T i m e ( m i n
153
TABLE 45
REPRESENTATIVE DATA FOR NEUTRALIZATION OF 2-NITROPROPANE BYSODIUMjGLYCOLATE IN ETHYLENE GLYCOL AT 0 .0 0 °
AS A FUNCTION OF INITIAL CONCENTRATION OF 2-NITROPROPANE
Run 141-IV Temp. = 0 .0 0 °
2 - N i t r o p r o p a n e NaO(CH^) OH =
= 0 . 1 1 1 M 0 .0 0 1 0 N
R X lO "^ Time(Ohms) Log [ ( 1 /R - 1 / R ^ ^ ) 1 0 ^ ] (M in . )
5 .9 8 5 7 E q u i l i b r i u m5 .5 5 0 0 1 .8 5 0 6 0 .0 06 .4 2 0 0 1 .6 6 7 3 2 .5 07 .1 7 0 0 1 .4 7 9 9 5 .0 07 .7 1 0 0 1 .3 1 0 1 7 .5 18 .0 8 0 0 1 .1 6 0 8 1 0 .0 18 .3 4 0 0 1 .0 2 6 1 1 2 .5 48 .7 4 6 0 0 .7 0 5 9 2 0 .3 09 .0 3 0 3 489 .0 8 1 3 • 689 .1 5 1 1 144 (oo)9 .1 7 4 4 1999 .2 5 5 8 ■ 443
S lo p e = 0 .0 6 8 3 m i n . ' l k = 0 . 1 5 7 / 0 . 1 1 1 = 1 . 42 l . / m . - m i n .
P lo t o f k in e t ic run 141-IV shoxm in F ig u r e 12.
2.000
1.500
S 1.000-
0.00 5.0 10.0 15.0 20.0Time (min.)
F igu re 12 .Ln
155
TABLE 46
OF 2-NITROPROPANE BYSODIUM GLYCOLATE IN ETHYLENE GLYCOL AT 0.00°
AS A FUNCTION OF INITIAL CONCENTRATION OF 2-NITROPROPANE
Run 1 4 4 - IV Temp. = 0 .0 0 °
2 - N i t r o p r o p a n e 0 .1 1 1 NaOCCHg) OH = 0 .0 0 0 1 3
MN
—AR X 10 Time
(Ohms) Log [ ( 1 / R - 1 /R q o )1 0 ] (M in . )
3 .3 6 8 5 E q u i l i b r i u m3 .8 0 0 0 1 .8 6 5 0 0 . 0 04 .2 8 0 0 1 .6 4 1 1 2 . 0 44 .6 5 0 0 1 .4 0 0 9 4 . 0 04 .8 9 4 0 1 .1 5 9 9 6 . 0 15 .0 3 3 0 0 .9 4 5 0 8 . 0 05 .1 1 5 0 0 .7 4 9 7 1 0 .0 05 .2 0 8 5 0 .3 2 4 3 1 5 .0 05 .2 3 5 6 0 .0 4 9 2 2 0 .0 05 .2 5 2 7 ' 3 0 .0 05 .2 5 7 9 425 .2 6 6 4 60 (oo)5 .2 6 5 7 95
S lo p e = 0 .1 1 2 m i n . " ^ k = 0 . 0 2 5 8 / 0 . 1 1 1 = 2 .3 2 1 . / m. - m i n .
Plot of kinetic run 144-IV shown in Figure 13.
F igu re 13.
1.500
.000
o>
0.500
0.00 5 .0 0 10.0T i m e ( mi n . )
15.0 Utcr>
157
TABLE 47
REPRESENTATIVE DATA FOR NEUTRALIZATION OF NITROCYCLOHEPTANE BY SODIUM GLYCOLATE
IN ETHYLENE GLYCOL AT 0 .0 0 °
Run 19-V N i t r o c y c l o h e p t a n e = 0 .0 3 6 6 MTemp. = 0 .0 0 ° NaOCCHg) OH = 0 .0 0 3 0 N
R X 10"4 Time(Ohms) Log [ ( 1 /R - 1 /R ^ ^ )1 0 ^ ] ( M i n . )
1 .3 4 2 7 E q u i l i b r i u m1 .3 6 0 0 1 .9 2 9 1 0 . 0 01 .4 1 1 0 1 .7 6 6 1 2 .0 41 .4 5 2 0 1 .5 8 3 6 4 . 0 11 .4 8 0 0 1 .4 0 3 5 6 . 0 11 .4 9 8 0 1 .2 3 5 5 8 .0 01 .5 0 9 6 1 .0 8 1 7 1 0 .0 11 .5 1 6 9 0 .9 4 8 4 1 2 .0 11 .5 2 9 6 0 .5 3 1 5 2 0 .0 01 .5 3 7 6 40 (oo]1 .5 3 9 9 60
- 1S lo p e = 0 .0 8 6 1 m in . k_ = 0 . 1 9 8 / 0 . 0 3 6 6 = 5 .4 1 l . / m . - m i n .
P lo t o f k in e t i c run 19-V shown in F igu re 14,
2.000
1.500
? 1.000
0 .5 0 0 .0.00 5 .0 0 10.0 15.0 20.0 M
U i
F igu re 14 . T i m e (min. )
Run
TABLE 48
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K^, OF NITROCYCLOBUTANE IN 33.3% BY WEIGHT METHANOL-WATER AT 2 5 .0 “
Fraction o f N itro Compound N eutralized
Age o f S ystem (m in .)
pH o f S y s tem a t
Time, t(m in .)(C alculated from Average pH Value)
17 9 -III 1/4
(Estimated time o f complete rea c t io n X 5 = 15.5 min.)
4882
107 420
2 d ay s
8.9008.6308.9088.7768 .1 2
3.99 X 10-1 0
pH (Avg.) = 8.904 - 0.004 (Avg. o f f i r s t and th ird readings)
1 8 8 -III 1 /4
(Estimated time o f complete rea c t io n X 5 = 15.5 min.)
12.413.214.2 15.1 16.8 17.620.521.524.5
8.9969.0089.0048.9999.0189.0329.033 9.0269.019
3.00 X 10-10
pH (Avg.) = 9.026 - 0 .004 (Avg. o f l a s t s i x readings)
LnVO
TABLE 48 (C ontinued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,OF NITROCYCLOBUTANE IN 33.3% BY WEIGHT METHANOL-WATER AT 25.0*
Fraction o f Nitro Run Compound N eutralized
Age o f System (m in.)
pH of System at
Time, t (m in .) (C alculated from Average pH Value)
1 8 3 -III 1/2 90 9.512 -10150 9.482 3.6 X 10(Estimated time o f complete 254 9.43r ea c t io n X 5 = 22.9 min.) 594 9.33
plL (Avg.) = 9 .47 - 0 .04 (Avg. o f f i r s t three readings)
1 8 7 -III 1 /2 13.7 9.50816.3 9.514
(Estimated time o f complete 17.6 9.521 -10rea c t io n X 5 = 22.9 min.) 19.6 9.523 2.85 X 10 •
24.1 9.52326.3 9.521
pH (Avg.) =■ 9 .522 ± 0 .001 (Avg. o f l a s t four readings)
o\o
TABLE 48 (C ontinued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K , OF NITROCYCLOBUTANE IN 33.3% BY WEIGHT METHANOL-WATER AT 2 5 .0 “N
Age of pH ofFraction o f Nitro System System at (C alculated from
Run Compound N eutralized (min.) Time, t (m in .) Average pH Value)
1 8 5 -III 3/4 66 .3 9.94071.0 9 .954
(Estimated time of complete .7 5 .9 9 .948— in
rea c t io n X 5 =■ 60.5 min.) 78.5 9.947 3.04 X 1085.3 9.943
101 9.943104 9.946105 9.946
pH (Avg.) - 9 .946 i 0 .002 (Avg. o f l a s t s i x readings)
K (Avg.) = (3 .04 + 2 .85 + 3 .00) X 10 N --------------------------------------
-10
2 .9 6 - 0 . 0 8 X 1 0 " ^ °
ON
TABLE 49
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K^, OF NITROCYCLOPENTANE IN 33.3% BY WEIGHT MILTHANOL-WATER AT 2 5 .0 “
RunFraction o f N itro
Compound N eutra lized
Age of System (min.)
pH of System at
Time, t (m in .)
S?(C alculated from Average pll Value)
220 -III 1 /4
(Estimated time of complete rea c t io n X 5 = 79.5 min.)
71.380.998.2110128
7.4387.4807.4607.4447.424
1.11 X 10- 8
pH (Avg.) =• 7.449 - 0 .017 (Avg. o f a l l readings)
138313891400142714421474
7.2907.3427.3767.4027.4087.420
1.22 X 10- 8
pH (Avg.) “ 7 .410 - 0.007 (Avg. o f l a s t three readings)
o\
TABLE 49 (C ontinued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K . OF NITROCYCLOPENTANE IN 33.3% BY WEIGHT METHANOL-WATER AT 2 5 .0 “N
Fraction o f N itro Run Compound N eutralized
Age of System (min.)
pH of System at
Time, t (m in .)
%N(C alculated from Average pH Value)
2 2 4 -III 1 /4 73 7.49684 7.488
1.27 X 10~®(Estimated time of complete 100 7.470rea c t io n X 5 = 79.5 min.) 126
1397.4607.458
' 160 7.454
pH (Avg.) = 7.457 i 0 .002 (Avg. o f l a s t three readings)
2 2 5 -I II 1 /4 3070 7.4681 .17 X 10"G3135 7.495
(Estimated time o f complete 3155 7.495r ea c t io n X 5 = 79.5 min.) +pH (Avg.) = 7.495 - 0 .000 (Avg. o f l a s t two readings)
w
TABLE 49 (C ontinued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,OF NITROCYCLOPENTANE IN 33.3% BY WEIGHT METHANOL-WATER AT 2 5 .0 “
Age o f pH o f %NF r a c t i o n o f N i t r o S y s tem S y stem a t ( C a l c u l a t e d fro m
Run Compound N e u t r a l i z e d ( m in . ) T im e, t ( m i n . ) A v e rag e pH V a lu e )
2 2 4 - I I I 1 /2 214 7 .6 5 4249 7 .6 6 6 2 .4 2 X lO 'G
( E s t i m a t e d t im e o f c o m p le te 272 7 .6 8 0r e a c t i o n X 5 = 143 m i n . ) 288 7 .6 8 4
pll (A v g .) =■ 7 .6 7 6 - 0 .0 0 7 (Avg. o f l a s t tr liree r e a d i n g s )
2 2 5 - I I I 1 /2 2869 7 .7 9 62900 7 .8 2 2 1 .6 4 X 1 0 "^
( E s t i m a t e d t im e o f c o m p le te 2925 7 .8 4 0r e a c t i o n X 5 = 143 m i n . ) 2951 7 .8 4 8
pH (A v g .) “ 7 .8 4 4 - 0 .0 0 4 (Avg. o f a l l r e a d i n g s )
o\
TABLE 49 (C ontinued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,OF NITROCYCLOPENTANE IN 33.3% BY WEIGHT METHANOL-WATER AT 25 .0*
Age o f pll o f %F r a c t i o n o f N i t r o S ys tem S ystem a t ( C a l c u l a t e d from
Run Compound N e u t r a l i z e d ( m i n . ) T im e , t ( m i n . ) A v e ra g e pH V a lu e )
2 2 5 - I I I 3 /4 379 7 .9 1 6 _Q464 7 .9 4 6 4 .5 9 X 10
( E s t i m a t e d t im e o f c o m p le te 504 7 .9 5 1r e a c t i o n X 5 = 300 m i n . )
pll (A v g .) = 7 .9 4 8 - 0 .0 0 2 (Avg. o f l a s t two r e a d i n g s )
1752 7 .9 6 41770 7 .9 9 71781 8 .0 2 01798 8 .0 4 9 3 .3 5 X 10"®1814 8 .0 6 81824 8 .0 7 61831 8 .1 0 6
pH (A v g .) = 8 .0 8 3 - 0 .0 1 5 (Avg. o f l a s t t h r e e r e a d i n g s )
(A v g .) = ( 1 . 2 2 + 1 .2 7 + 1 . 1 7 ) X lO 'G3
= 1 .2 2 ± 0 .0 5 X 1 0 -8
TABLE 50
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K , OF NITROCYCLOIIEXANE IN 33.3% BY WEIGHT METHANOL-WATER AT 2 5 .0 °N
F r a c t i o n o f N i t r o Run Compound N e u t r a l i z e d
Age o f Sys tem ( m i n . )
pH o f S y s tem a t
T im e, t ( m i n . )
KN
( C a l c u l a t e d f ro m A v e ra g e pH V a lu e )
1 9 0 - I I I 1 /4 678 8 .3 7 3686 8 .4 1 7 - 9
( E s t i m a t e d t im e o f c o m p le te 688 8 .4 4 0 1 .0 0 X 10r e a c t i o n X 5 = 385 m in . ) 695 8 .4 8 0
699 8 .4 9 7
pH (A v g .) = 8 .4 5 8 - 0 .0 3 0 (Avg. o f l a s t f o u r r e a d i n g s )
1420 8 .2 9 81433 8 .3 4 4 _91438 8 .3 5 4 1 .2 6 X 101457 8 .3 8 6
pH (A v g .) = 8 .3 6 1 ± 0 .0 1 6 (Avg. o f l a s t t h r e e r e a d i n g s )
o\o\
TABLE 50 (Continued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K , OF NITROCYCLOHEXANE IN 33.3% BY WEIGHT METHANOL-WATER AT 25.0°N
F r a c t i o n o f N i t r o Run Compound N e u t r a l i z e d
Age o f S ystem ( m i n . )
pH o f S ys tem a t
T im e, t ( m i n . )
KN
( C a l c u l a t e d from A v e ra g e pH V a lu e )
1 8 9 - I I I 1 /2 7 1 5 .9 9 .0 7 17 1 9 .0 9 .1 8 1
( E s t i m a t e d t im e o f c o m p le te 7 2 1 .8 9 .2 1 0r e a c t i o n X 5 = 478 m i n . ) 7 2 7 .2 9 .2 3 8
, 7 2 9 . 2 9 .2 2 9 4 .9 0 X 1 0 " 1 °7 3 1 .5 9 .2 2 47 3 3 .4 9 .2 2 17 3 7 .2 9 .2 1 67 4 0 .9 9 .2 1 4
pH (A v g .) = 9 .2 2 2 - 0 .0 0 7 (Avg. o f l a s t 7 r e a d i n g s )
1496 8 .7 5 61507 8 .8 1 21516 8 .8 2 61524 8 .8 5 2 —91532 8 .8 5 7 1 .0 7 X 101540 8 .8 7 21560 8 .8 8 21568 8 .8 8 61578 8 .8 9 0
pH (A v g .) = 8 .8 8 2 - 0 .0 0 5 (Avg. o f l a s t 4 r e a d i n g s )
TABLE 50 (Continued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K^, OF NITROCYCLOHEXANE IN 33.3% BY WEIGHT METHANOL-WATER AT 25.0°
Age o f pH o fF r a c t i o n o f N i t r o S ys tem S y stem a t ( C a l c u l a t e d fro m
Run Compound N e u t r a l i z e d ( m i n . ) T im e, t (m in , . ) A v e rag e pH V a lu e )
1 8 9 - I I I ( c o n t ' d . ) 1 /2 2908 8 .6 2 12951 8 .6 6 1 q
( E s t i m a t e d t im e o f c o m p le te 2960 8 .6 6 9 1 .7 5 X 10r e a c t i o n X 5 = 478 m in . ) 2970 8 .6 6 7
2995 8 .6 7 83 0 1 0 8 .6 8 6
pH (A v g .) = 8 .6 6 8 - 0 .0 0 1 (Avg. o f r e a d i n g s 3 , 4 and 5)
2 4 0 - I I I 1 /2 395 8 .0 4 7407 8 .1 1 1
( E s t i m a t e d t im e o f c o m p le te 415 8 .1 0 2 1 .4 0 X 10"9r e a c t i o n X 5 = 478 m i n . ) 502 8 .1 0 4
1370 8 .7 5 51403 8 .7 9 9
pH (Avg. ) = 8 .7 7 7 - 0 .0 2 2 (Avg. o f l a s t 2 r e a d i n g s )
o\00
TABLE 50 (Continued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K , OF NITROCYCLOHEXANE IN 33.3% BY WEIGHT METHANOL-WATER AT 25.0°N
F r a c t i o n o f N i t r o Run Compound N e u t r a l i z e d
Age o f S y s tem ( m i n . )
pH o f S y s tem a t
T im e, t ( m i n . )( C a l c u l a t e d from A v e ra g e pH V a lu e )
1 9 0 - I I I ( c o n t ' d . ) 1 /4 2916 8 .3 3 72929 8 .3 5 9
( E s t i m a t e d t im e o f c o m p le t e 2940 8 ,3 7 0r e a c t i o n X 5 = 385 r a in . ) 2950 8 .3 8 1 —9
2958 8 .3 9 0 1 .1 1 X 10" 2968 8 .3 9 7
2979 8 .4 0 22993 8 .4 1 03016 8 .4 1 43024 8 .4 1 7
pH (A v g .) = 8 .4 1 4 i 0 .0 0 2 (Avg. o f l a s t f o u r r e a d i n g s )
2 3 9 - I I I 1 / 4 290 8 .4 3 2310 8 .4 0 5
( E s t i m a t e d t im e o f c o m p le t e 344 8 .4 1 7 1 .1 4 X 10"9r e a c t i o n X 5 = 385 m i n . ) 1318 8 .3 0 2
1348 8 .3 9 61372 8 .4 3 0
pH (A v g .) = 8 .4 1 6 - 0 .0 1 2 (Avg. o f r e a d i n g s 1 , 2 , 3 , 5 and 6)ONVD
TABLE 50 (Continued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K^, OF NITROCYCLOHEXANE IN 33.3% BY WEIGHT METHANOL-WATER AT 25.10°
RunF r a c t i o n o f N i t r o
Compound N e u t r a l i z e d
Age o f S y s tem ( m i n . )
pH o f S y s tem a t
T im e, t ( m i n . )( C a l c u l a t e d f ro m A v e ra g e pH V a lu e )
2 4 0 - I I I 3 /4 156015681608
9 .7 6 79 .7 6 09 .6 7 4
I11
4 . 5 1 X 1 0 " 1 °
pH (A v g .) = 9 .6 7 4 - 0 .0 0 6 (Avg. o f a l l r e a d i n g s )
(A v g .) = ( 1 .0 7 + 1 .2 6 + 1 .1 1 + 1 . 40) X 1 0 -9
4
1 .2 1 ± 0 .1 2 X 1 0 -9
o
TABLE 51
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K , OF NITROCYCLOHEPTANE IN 33 .3% BY WEIGHT METHANOL-WATER AT 2 5 . 0 “N
Age o f pH of KpjFraction o f N itro System System it (Calculated from
Run Compound N eutralized (min.) Time, t (m ln .) Average pH Value)
2 4 1 - I I I 1 /4 345 7 .4 8 4379 7 .5 0 6 1 .0 4 X 10“ ®395 7 .5 0 6419 7 .4 7 8
pH (Avg'.) = 7 .4 9 3 - 0 .0 1 2 (Avg. o f a l l r e a d i n g s )
1131 7 .3 4 21152 7 .3 7 5 1 .3 7 X 10“1174 7 .3 7 8
pH (A v g .) = 7 .3 7 6 - 0 . 0 0 1 (Avg. o f l a s t 2 r e a d i n g s )
TABLE 51 (C ontinued)
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K^, OF NITROCYCLOHEPTANE IN 33.3% BY WEIGHT METHANOL-WATER AT 2 5 .0 °
Fraction o f N itro Run Compound N eutralized
Age o f System (m in.)
pH of System a t
Time, t (m in .)(C alculated from Average pH Value)
2 4 2 -III 1 /2 43 7.83253 7.984
(Estimated time o f complete 60 7.960rea c t io n X 5 = 352 min.) 87 7.810
99 7.776 —R323 7.624 2.06 X 10362 7.653397 7.664
1418 7.6601440 7.674
pH (Avg.) = 7.667 - 0 .007 (Avg. o f l a s t 2 readings)
2 4 3 -III 1 /2 1629167517241752
7.5627.5947.6167.622
2.36 X 10-8
pH (Avg.) ■= 7 .611 - 0 .011 (Avg. o f l a s t 3 readings)
NJ
TABLE 51 (C ontinued)
REPRESENTATIVE DATA FOR DETERMINATION OF TUE DISSOCIATION CONSTANT,K^, OF NITROCYCLOHEPTANE IN .33.3% BY WEIGHT METHANOL-WATER AT 2 5 .0 “
RunF r a c t i o n o f N i t r o
Compound N e u t r a l i z e d
Age o f S ystem ( m i n . )
pli o f S y s tem a t
T im e, t ( m i n . )
KN
( C a l c u l a t e d f ro m A v e ra g e pH V a lu e )
2 4 3 - I I I ( C o n t ' d . ) 1 / 2
( E s t i m a t e d t im e o f c o m p le te r e a c t i o n X 5 = 352 m i n . )
3 /4
( E s t i m a t e d t im e o f c o m p le te r e a c t i o n X 5 = 440 m i n . )
16161630165216661684
7 .6 0 37 .6 1 27 .6 1 77 .6 2 07 .6 2 4
pH (A v g .) = 7 .6 1 8 - 0 .0 0 4 (Avg. o f l a s t 4 r e a d i n g s )
2 .3 2 X 10-8
1574160016241666
7 .8 0 27 .8 7 67 .8 4 67 .8 2 0
3 .9 4 X 10-8
pH (A v g .) = 7 .8 4 7 ^ 0 .0 2 1 (Avg. o f l a s t 3 r e a d i n g s )
X (A v g .) = ( 2 .0 6 + 2 .3 6 + 2 .3 2 ) X 10” ®
= 2 .2 5 - 0 . 1 2 X 10“ ®
LO
TABLE 52
REPRESENTATIVE DATA FOR DETERMINATION OF THE DISSOCIATION CONSTANT,K^, OF NIÏROCYCLOOCTANE IN 33.3% BY WEIGHT METHANOL-WATER AT 2 5 .0 °
RunF r a c t i o n o f N i t r o
Compound N e u t r a l i z e d
Age o f S ystem (m in . )
pH o f S ys tem a t
T im e, t ( m i n . )
%N( C a l c u l a t e d f ro m A v e ra g e pH V a lu e )
2 4 4 - I I I 1 /2 16251658
7 .5 3 27 .5 3 8 4 .8 2 X 10“ ®
pli (A v g .) =>
1696'1 7 1 4
1746
7 .5 3 5 - 0 .0 0 3
7 .4 3 67 .4 3 27 .4 1 5
6 .2 5 X 10~®
pH (A v g .) = 7 .4 2 8 - 0 .0 0 8
2 4 5 - I I I 1 /2 40394082
7 .4 6 87 .4 7 8 5 .5 6 X 10“ ®
pH (A v g .) = 7 .4 7 3 - 0 .0 0 5
S , (Avg. ) = ( 4 .8 2 + 6 .2 5 + 5 . 5 6 ) X 10“ ®
3
= 5 .5 4 ± 0 .4 8 X 10“ ®
175
TABLE 53
REPRESENTATIVE DATA FOR DEUTERATION OF 2-NITRGPRGPANE CATALYZED BY TRIETHYLAMINE IN
DEUTERIUM GXIDE-DIMETHYLFGRMAiMIDE AT 3 8 °
Run 53-1 Temp. = 38°
2 - N i t r o p r o p a n e = T r i e t h y la m in e =
1 .9 M 0 .1 2 M
A( a r e a u n d e r p e a k
i n s q . i n . )
A /A 0 lo g (A ^ /A ) Time (M in . )
1 .7 5 1 .0 0 0 .0 0 0 0 . 01 .5 9 1 .1 0 0 .0 4 2 5 . 51 .6 1 1 .0 9 0 .0 3 8 7 .91 .5 6 1 .1 2 0 .0 4 9 1 0 .91 .4 7 1 .1 9 0 .0 7 6 1 5 .51 .2 6 1 .3 9 0 .1 4 3 2 7 .91 .1 8 1 .4 8 0 .1 7 0 3 5 .1
- 3 - 1 - 2 - 1S lo p e = 5 . 1 X 10 m in . k^ = 1 . 2 X 10 min.
P lo t o f k i n e t i c run 53-1 shown in F ig u re 15 .
35.0
30.0
}25 .0
E20.0
15.0
10.0
5.0
00 0.05 0.10Log
0.15 0.20F i g u r e 1 5 .
177
TABLE 54
RATE CONSTANTS FOR NEUTRALIZATION OF 2-NITROPROPANEBY TRIETHYLAMINE IN 50% BY VOLUME
1 , 2-DIMETHOXYETHANE-WATER
T e m p e r a tu r e [Et^N] k ( l . / m . - m i n . ) 2
0 .0 0 ° 0 .2 1 5 0 .0 6 6 4. 0 .2 1 3 0 . 0 6 3 8
0 .2 0 8 0 .0 6 6 40 .2 0 8 0 .0 6 4 5
k2
( a v g . ) = 0 .0 6 5 3 - 0 .0 0 1 1 l . / m . - m i n .
1 0 .0 8 ° 0 .2 3 9 0 .1 4 10 .2 3 9 0 . 1 3 80 .2 3 9 0 .1 4 70 .2 1 0 0 .1 4 4
( a v g . ) = 0 .1 4 2 - 0 .0 0 3 l . / m . - m i n .
1 9 .9 6 ° 0 .2 0 8 0 . 2 7 40 .2 0 8 0 . 2 8 10 .2 0 8 0 . 2 8 10 .2 0 8 0 .2 7 7
( a v g . ) = 0 .2 7 7 - 0 .0 0 3 l . / m . - m i n .
AH* = 1 1 .8 k c a l . / m o l e
AS* = - 2 8 .8 c a l . /m o le -d e g .
178
TABLE 55
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOBUTANEBY TRIETHYLAMINE IN 50% BY VOLUÎffi
, 1 , 2-DIMETHOXYETlIANE-WATER
T e m p e ra tu re [E t^N ] k1 2 ( 1 . / m . - m i n . )
0 .0 0 ° 0 .2 1 4 1 .7 70 .2 1 4 1 .8 20 .2 1 4 1 .8 70 .2 1 4 1 .8 7
" 2( a v g . ) = 1 .8 3 ± 0 .0 4 l . / m . - m i n .
1 0 .0 8 ° 0 .2 1 4 3 .5 70 .2 1 4 3 .4 90 .2 1 4 3 .4 10 .2 1 4 3 . 4 3
%2( a v g . ) = 3 .4 8 - 0 .0 6 l . / m . - m i n .
1 9 .9 6 ° 0 .2 1 4 6 .3 60 .2 1 4 6 .2 60 .2 1 4 6 .5 00 .2 1 4 6 .5 4
" 2( a v g . ) = 6 .4 1 - 0 .1 0 l . / m . - m i n .
A H* = 9 .8 8 k c a l . / m o l e
A S* = - 3 3 . 8 c a l . / m o l e - d e g .
P l o t o f t h e T h erm o d y n am ic R e l a t i o n Log ( k „ /T ) V e r s u s (1 /T ) shown i n F i g u r e 1 7 , p ag e 1 8 5 .
179
TABLE 56
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOPENTANEBY TRIETHYLAMINE IN 50% BY VOLUME
1 , 2-DIMETHOXYETHANE-WATER
T e m p e ra tu r e [Et^N] k ^ ( l . / m . - r a i n . )
0 .0 0 ° 0 .2 0 8 0 .3 2 70 .2 0 8 0 .3 3 10 .2 0 8 0 .3 0 30 .2 1 0 0 .3 3 2
“ 2( a v g . ) = 0 .3 2 3 - 0 .0 1 0 l . / m . - m i n .
1 0 .0 8 ° 0 .2 0 7 0 .6 4 8 ,0 .2 0 7 0 .6 3 90 .2 0 7 0 .5 3 90 .2 1 0 0 .6 4 1
“ 2( a v g . ) = 0 .6 4 1 - 0 .0 0 3 l . / m . - m i n .
1 9 .9 6 ° 0 .2 0 9 1 .2 00 .2 0 9 1 .1 80 .2 0 9 1 .1 80 .2 1 0 1 .1 9
k ( a v g . ) = 1 .1 9 - 0 . 0 1 l . / m . - m i n .2
AH* = 9 . 9 3 k c a l . / m o l e
AS* = - 3 2 .4 c a l . /m o le -d e g .
180
TABLE 57
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOHEXANEBY TRIETHYLAMINE IN 50% BY VOLUME
1 , 2-DIMETHOXYETHANE-WATER
T e m p e ra tu re [E t]N ] k ^ ( l . / m . - m i n . )
0 .0 0 ° 0 .2 0 8 0 .0 4 5 30 .2 0 8 0 .0 4 2 30 .2 0 8 0 .0 4 4 70 .2 0 1 0 .0 4 5 0
k2
( a v g . ) = 0 .0 4 4 3 - 0 .0 0 1 0 l . / m . - m i n .
1 0 .0 8 ° 0 .2 0 5 0 .0 9 2 30 .2 0 5 0 .0 9 0 00 .2 1 0 0 .0 9 5 20 .2 1 0 0 .0 9 5 7
" 2( a v g . ) = 0 .0 9 3 3 - 0 .0 0 2 2 l . / m . - m i n .
1 9 .9 6 ° 0 .2 0 7 0 .2 2 40 .2 0 7 0 .2 1 50 .2 1 1 0 .2 1 40 .2 1 1 0 .2 1 8
( a v g . ) = 0 .2 1 8 - 0 .0 0 4 l . / m . - m i n .
AH* = 1 1 .3 k c a l . / m o l e
AS* = -3 1 .2 c a l . /m o le -d e g .
181
TABLE 58
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOHEPTANEBY TRIETHYLAMINE IN 50% BY VOLUME
1 , 2-DIMETHOXYETlIANE-WATER
T e m p e r a t u r e [Et^N] k ^ C l . / m . - m i n . )
0 .0 0 ° 0 .2 1 4 0 .2 9 20 .2 1 4 0 .2 9 50 .2 1 4 0 .2 9 00 .2 1 4 0 .2 7 2
k ( a v g . ) = 0 . 2 8 7 - 0 .0 0 8 l . / m . - m i n .2
1 0 .0 8 ° 0 .2 1 4 0 .5 1 40 .2 1 4 0 .5 1 00 .2 1 4 0 .4 7 60 .2 1 4 0 .4 8 5
k^ ( a v g . ) = 0 .4 9 6 - 0 .0 1 6 l . / m . - m i n .
1 9 .9 6 ° 0 .2 1 4 ' 0 .8 6 50 .2 1 4 0 .9 1 40 .2 1 4 0 .9 1 40 .2 1 5 0 .8 2 0
k ^ ( a v g . ) = 0 . 8 7 8 - 0 .0 3 6 l . / m . - m i n .
AH* = 8 . 0 1 k c a l . / m o l e
AS* = - 4 0 . 3 c a l . / m o l e - d e g .
182
TABLE 59
RATE CONSTANTS FOR NEUTRALIZATION OF NITROCYCLOOCTANEBY TRIETHYLAMINE IN 50% BY VOLUl-IE
1 , 2-DIMETHOXYETHANE-WATER
T e m p e r a tu r e [E t^N ] ( 1 . / m . - r a i n . )
0 . 0 0 ° 0 .2 1 4 0 .1 9 30 .2 1 4 0 .1 9 50 .2 1 4 0 .1 8 50 .2 1 4 0 .1 8 0
( a v g . ) = 0 .1 8 8 - 0 . 0 0 6 l . / m . - m i n .
1 0 .0 8 ° 0 .2 1 4 0 .3 6 00 .2 1 4 0 .3 6 70 .2 1 4 0 .3 6 30 .2 1 4 0 .3 7 7
( a v g . ) = 0 .3 6 7 - 0 . 0 0 5 l . / m . - m i n .
1 9 .9 6 ° 0 .2 1 5 0 .6 2 40 .2 1 5 0 .6 9 90 .2 1 5 -JO .6520 .2 1 5 0 .6 5 7
( a v g . ) = 0 .6 5 8 - 0 . 0 2 0 l . / m . - m i n .
AH* = 9 . 3 8 k c a l . / m o l e
AS* = - 3 5 .5 c a l . /m o le -d e g .
183
TABLE 60
I REPRESENTATIVE DATA FOR NEUTRALIZATION OF NITROCYCLOHEXANE BYTR:;iETliYLAMINE IN 50% BY VOLUME 1 , 2-DIMETHOXYETHANE-UATER AT 0 .0 0 '
I Run 2 1 7 -1 17 Temp. = 0 .0 0 °
N i t r o c y c l o h e x a n e = a p p ro x . T r i e t h y l a m i n e =
0 .0 0 5 8 M 0 .2 0 8 M
' (1/R) X 10^ Time(Ohms~^) Log [ ( 1 / R - 1 /R ^ ^ ) 1 0 * ] (M in . )
1 4 .7 5 E q u i l i b r i u m1 4 .8 0 1 .3 9 7 9 0 . 0 02 1 .0 9 1 .2 7 2 1 3 9 .9 12 3 .9 4 1 .2 0 0 3 5 9 .9 22 6 .6 1 1 .1 2 0 2 7 9 .9 42 8 .8 3 1 .0 4 0 2 . 9 9 .9 43 0 .7 6 0 .9 5 6 2 1 2 0 .5 23 2 .2 3 0 .8 7 9 1 1 3 9 .9 73 3 .5 4 0 .7 9 6 6 1 6 0 .0 03 4 .7 2 0 .7 0 5 9 1 8 2 .2 03 5 .5 0 0 .6 3 3 5 2 0 0 .2 83 6 .7 2 0 .4 8 8 6 2 3 4 .0 03 7 .5 6 0 .3 5 0 2 2 6 1 .9 83 8 .2 0 0 .2 0 4 1 3 0 1 .1 03 9 .6 6 4753 9 .6 5 5863 9 .8 0 11853 9 .8 0 1216
2 Slope = 0 .0 0 4 0 4 —1m in . = 0 .0 4 4 7 l . / m . - m i n .•
E îlo t o f k i n e t i c run 217-11 shown in F ig u r e 1 6 .
. 5 0 0
1.000
' 8
j
o
0 .5 0 0
0.200 L_ 0.00 3 0 0 . 0 0100.00 200.00
F igure 16.T i m e ( mi n.)
CO
- 1.500
- 1.750
C \ J
2.000h
3.703.603.40 3.50F igure 17 . 1/ T X IQ3 00
Ln
