Microwave Assisted Solvent-free Synthesis of Some Imine Derivatives
6
Research Article Microwave Assisted Solvent-Free Synthesis of Some Imine Derivatives Yunus Bekdemir 1 and KürGat Efil 1,2 1 Department of Molecular Biology and Genetics, Faculty of Arts and Science, Canik Basarı University, 55080 Samsun, Turkey 2 Department of Chemistry, Faculty of Arts and Sciences, Ondokuz Mayis University, 55139 Samsun, Turkey Correspondence should be addressed to Yunus Bekdemir; [email protected] Received 2 January 2014; Revised 23 February 2014; Accepted 24 February 2014; Published 26 March 2014 Academic Editor: Joseph E. Saavedra Copyright © 2014 Y. Bekdemir and K. Efil. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Some imine derivatives (1a–7d) were synthesized using a rapid and an environmentally friendly method with reaction of aromatic aldehydes (a–d) and aromatic amines (1–7) (in 1 : 1 molar ratio) in the presence of -ethoxyethanol as a wetting reagent (2 drops) under solvent-free conditions using microwave heating. 1. Introduction Compounds containing the –C=N– (azomethine group) structure are known as Schiff bases, usually synthesized from the condensation of primary amines and active carbonyl groups [1]. e reaction is acid-catalyzed and is generally carried out by refluxing the carbonyl compound and amine, with an azeotroping agent if necessary, and separating the water as formed [2]. Schiff bases are well known for their biological applications as antibacterial, antifungal, anticancer, and antiviral agents; furthermore, they have been used as intermediates in medical substrates and as ligands in complex formation with some metal ions [1, 3]. e synthesis of imines was firstly reported by Hugo Schiff in 1864 and they have been known since then [4]. e imine compounds have been prepared using molecular sieves [5, 6], infrared irradiation [7], Mg(ClO 4 ) 2 [8], P 2 O 5 /SiO 2 [9], ZnCl 2 [10], CaO under microwave power [11], ethyl lactate as a tunable solvent [12], K10 clay [13], TiCl 4 [14], alumina [15], CeCl 3 ⋅7H 2 O [16], ultrasound irradiation [17], polymer-supported [18], nanotube TiO 2 (in sunlight) [19], and Ti(OEt) 4 [20, 21]. e present work reveals the comparative aspects of con- densation of some aromatic amines with aldehyde derivatives using microwave and conventional methods. e amine and aldehyde compounds as starting materials, -ethoxyethanol (-EE) as wetting reagent and microwave power as an effective source of heating are used in this study. e cor- responding imine compounds were prepared in high yields and short reaction times using this effective and environment friendly method. 2. Results and Discussion In this work, we synthesized quickly and efficiently a series imine derivatives (1a–7d) by condensation of some aromatic amines (1–7) and aldehyde derivatives such as salicylaldehyde (a), p-chlorobenzaldehyde (b), p-methoxybenzaldehyde (c) and cinnamaldehyde (d) under microwave-assisted solvent- free conditions using -EE as wetting reagent. -EE that is a polar molecule quickly absorbs microwaves and therefore heats up and heats around effectively. As a result, -EE, which increases the polarity of the reaction medium, has an active role in the heating of the reaction medium by microwaves. e general reaction was summarized in Scheme 1. In addition, we tested the effect of different microwave power such as 180, 360, 600, 900 W and detected the microwave power of 180 W and 360 W are more appropriate choices for the reaction. Hence, the optimum microwave reaction conditions were determined using 180 and 360 W microwave power and neat and wetting with -EE for compound 1a. e highest reaction yield (94%) and shorter reaction time Hindawi Publishing Corporation Organic Chemistry International Volume 2014, Article ID 816487, 5 pages http://dx.doi.org/10.1155/2014/816487
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Transcript of Microwave Assisted Solvent-free Synthesis of Some Imine Derivatives
Research ArticleMicrowave Assisted Solvent-Free Synthesis ofSome Imine Derivatives
Yunus Bekdemir1 and KuumlrGat Efil12
1 Department of Molecular Biology and Genetics Faculty of Arts and Science Canik Basarı University 55080 Samsun Turkey2Department of Chemistry Faculty of Arts and Sciences Ondokuz Mayis University 55139 Samsun Turkey
Correspondence should be addressed to Yunus Bekdemir bekdemirbasariedutr
Received 2 January 2014 Revised 23 February 2014 Accepted 24 February 2014 Published 26 March 2014
Academic Editor Joseph E Saavedra
Copyright copy 2014 Y Bekdemir and K Efil This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
Some imine derivatives (1andash7d) were synthesized using a rapid and an environmentally friendly method with reaction of aromaticaldehydes (andashd) and aromatic amines (1ndash7) (in 1 1 molar ratio) in the presence of 120573-ethoxyethanol as a wetting reagent (2 drops)under solvent-free conditions using microwave heating
1 Introduction
Compounds containing the ndashC=Nndash (azomethine group)structure are known as Schiff bases usually synthesized fromthe condensation of primary amines and active carbonylgroups [1] The reaction is acid-catalyzed and is generallycarried out by refluxing the carbonyl compound and aminewith an azeotroping agent if necessary and separating thewater as formed [2] Schiff bases are well known for theirbiological applications as antibacterial antifungal anticancerand antiviral agents furthermore they have been used asintermediates inmedical substrates and as ligands in complexformationwith somemetal ions [1 3]The synthesis of imineswas firstly reported by Hugo Schiff in 1864 and they havebeen known since then [4] The imine compounds have beenprepared using molecular sieves [5 6] infrared irradiation[7] Mg(ClO
4)2[8] P
2O5SiO2[9] ZnCl
2[10] CaO under
microwave power [11] ethyl lactate as a tunable solvent[12] K10 clay [13] TiCl
4[14] alumina [15] CeCl
3sdot7H2O
[16] ultrasound irradiation [17] polymer-supported [18]nanotube TiO
2(in sunlight) [19] and Ti(OEt)
4[20 21]
The present work reveals the comparative aspects of con-densation of some aromatic amines with aldehyde derivativesusing microwave and conventional methods The amine andaldehyde compounds as starting materials 120573-ethoxyethanol(120573-EE) as wetting reagent and microwave power as an
effective source of heating are used in this study The cor-responding imine compounds were prepared in high yieldsand short reaction times using this effective and environmentfriendly method
2 Results and Discussion
In this work we synthesized quickly and efficiently a seriesimine derivatives (1andash7d) by condensation of some aromaticamines (1ndash7) and aldehyde derivatives such as salicylaldehyde(a) p-chlorobenzaldehyde (b) p-methoxybenzaldehyde (c)and cinnamaldehyde (d) under microwave-assisted solvent-free conditions using 120573-EE as wetting reagent 120573-EE that isa polar molecule quickly absorbs microwaves and thereforeheats up and heats around effectively As a result120573-EE whichincreases the polarity of the reaction medium has an activerole in the heating of the reaction medium by microwaves
The general reaction was summarized in Scheme 1 Inaddition we tested the effect of different microwave powersuch as 180 360 600 900W and detected the microwavepower of 180W and 360W are more appropriate choicesfor the reaction Hence the optimum microwave reactionconditions were determined using 180 and 360Wmicrowavepower and neat and wetting with 120573-EE for compound 1aThe highest reaction yield (94) and shorter reaction time
Hindawi Publishing CorporationOrganic Chemistry InternationalVolume 2014 Article ID 816487 5 pageshttpdxdoiorg1011552014816487
2 Organic Chemistry International
Ar
ArH
O
+ NH2 R
2
R1
R3
R2
R1
R3
Microwave N
(andashd) (1andash7d)(1ndash7)
Scheme 1
Table 1 The optimization of microwave conditions for compound1a
Microwave methodWatt Time (min) Reaction conditions Yield ()180 5 Wetting (with 120573-EE) 83360 5 Wetting (with 120573-EE) 93360 15 Wetting (with 120573-EE) 94360 5 Neat 88360 15 Neat 81
Table 2 The optimization of classical conditions for compound 1a
Classical methodTime (min) Yield () Reaction conditions30 64 Reflux60 73 Reflux120 76 Reflux240 75 Reflux1300lowast 74 RefluxProcedure 1mmol aldehyde (10mL of ethanol) and 1mmol amine (10mL ofethanol) are mixed a balloon and then boiled under reflux on a hot platelowast300min (heated) + 1000min (unheated)
(15min) were obtained at 360W microwave power with 120573-EE In the absence of wetting reagent the reaction yields are81 for 15 minutes and 88 for 5 minutes It is understoodthat the reaction yield was increased by wetting reagentthat increases the polarity of the reaction medium Theoptimization of microwave-assisted conditions was given inTable 1
In addition we have synthesized some imine derivatives(1a4a 1b4b 1c4c 1d4d) under classical conditions using asolvent (azeotropic) and traditional heating source (hot plate)for comparison with microwave conditions Firstly synthesisof compound 1a under the classical reaction conditions wastested at various periods of time (30 60 120 240 1300min) todetermine the optimumreaction timewhichwas determinedas 120 minutes Information on the optimization of thereaction time of compound 1a for classic conditions waspresented in Table 2
The compounds 1a 4a 1b 4b 1c 4c 1d and 4d wereobtained at 76 73 63 79 67 73 67 and75 yields respectively in 120 minutes under the classi-cal reaction conditions whereas in microwave conditions
0
20
40
60
80
100
Yiel
d (
)
Compound
MicrowaveClassical
1a 4b1b4a 4d1d4c1c
Figure 1 Comparison of yields under the microwave and classicalconditions
the corresponding reaction yields were 94 97 95 9891 97 95 and 96 respectively in 10ndash15 minutes Allthe results such as reactions time yields and melting pointsof the compounds were presented in Table 3 In addition theyields of microwave and conventional reaction conditions forsome imines were expressed graphically in Figure 1
3 Conclusion
In conclusion we have developed a simple microwaveassisted solvent-free method for the synthesis of imines usinga wetting reagent (120573-ethoxyethanol) The method workswell for the reaction of this type amines and aldehydesBecause we have synthesized imine compounds for goodyields and fast reaction times in our method Our methodhas some advances such as higher reaction yields shorterreaction times and green reaction conditions than classicalrequirements used of a solvent and conventional heat source(like hot plate) and other some microwave methods used ofcatalyst and solid supports In addition some imines weresynthesized for the first time by us with this study
4 Experimental
All of the chemicals were obtained from commercial sourcesor prepared according to standard methods Melting points
Organic Chemistry International 3
Table 3 Synthesis of imine derivatives under microwave irradiation
N Ar R1
R2
R3
Microwavea Classicalb mp ∘C Lit mp ∘CYield 119905min Yield 119905min
1a
OH
OH H H 94 15 76 120 188ndash190 190 [22]2a OH H Cl 93 15 mdash mdash 159ndash162 156ndash1565 [23]3a OH CH3 H 93 15 mdash mdash 199ndash202 mdash4a H H H 97 10 73 120 50ndash53 50-51 [24]5a H Cl H 94 15 mdash mdash 103ndash105 104 [12]6a H CH3O H 96 15 mdash mdash 83ndash85 82ndash835 [25]7a H CH3 H 97 15 mdash mdash 93-94 90ndash915 [25]1b
Cl
OH H H 95 15 63 120 116ndash118 117 [26]2b OH H Cl 92 20 mdash mdash 123ndash125 mdash3b OH CH3 H 91 20 mdash mdash 134ndash137 mdash4b H H H 98 10 79 120 63ndash66 64-65 [24]5b H Cl H 94 15 mdash mdash 110-111 110-111 [24]6b H CH3O H 91 30 mdash mdash 124ndash126 124-125 [27]7b H CH3 H 93 15 mdash mdash 126ndash128 125 [27]1c
H3CO
OH H H 91 15 67 120 90-91 91ndash93 [22]2c OH H Cl 95 10 mdash mdash 86ndash88 mdash3c OH CH3 H 93 15 mdash mdash 86-87 mdash4c H H H 97 10 73 120 58ndash60 63ndash635 [24]5c H Cl H 97 15 mdash mdash 90ndash92 92 [16]6c H CH3O H 95 15 mdash mdash 147ndash149 145-146 [24]7c H CH3 H 91 15 mdash mdash 92-93 91-92 [24]1d OH H H 95 15 67 120 89ndash91 92 [22]2d OH H Cl 91 15 mdash mdash 91ndash93 mdash3d OH CH3 H 94 15 mdash mdash 97-98 mdash4d H H H 96 10 75 120 108ndash111 108-109 [12]5d H Cl H 96 15 mdash mdash 105ndash107 105 [12]6d H CH3O H 97 15 mdash mdash 120-121 119-120 [12]7d H CH3 H 90 15 mdash mdash 75ndash77 76-77 [28 29]aUnder solvent-free reaction using microwavebProcedure 1mmol aldehyde (10mL of ethanol) and 1mmol amine (10mL of ethanol) are mixed a balloon and then boiled under reflux on a hot plate
were determined with an Electrothermal 9100 apparatusThe infrared absorption spectrum of the compounds hasbeen recorded in the region at 4000 and 400 cmminus1 rangeusing a Bruker Vertex 8080 v spectrophotometer using KBrpressed pellet technique at room temperature The 1H NMRand 13C NMR spectra were recorded using a Bruker AC200NMR 200MHz spectrometer in CDCl
3-1198891and DMSO-
1198896using TMS as the internal standard Elemental analyses
were conducted at the METU Central Laboratory using aLECO CHNS-932 All syntheses were carried out in A BoshHMT 812C modified microwave oven
General Procedure for Preparation of 1andash7d Aldehyde(1mmoL) amine (1mmoL) and two drops of 120573-ethox-yethanol as awetting reagentweremixed in a beakerThen thebeaker was placed in the microwave oven and was exposedto microwave irradiation (360W) The product obtainedby reaction was washed with cold ethanol Then it was
recrystallized in ethanolThe physical and spectra data of thecompounds 3a 2b 3b 2c 3c 2d and 3d are as follows
N-(Salicylidene)-2-hydroxy-4-methylaniline (3a) Mp 199-202∘C IR 3033 2965 2916 2858 1612 (C=N) 1592 15271486 1422 1278 1221 1141 1113 1012 869 788 754 720 622587 556 cmminus1 1H NMR (DMSO-d
6) 120575 894 (s 1H N=CH)
1390 (s 1H OH) 965 (s 1H OH) 13C NMR (DMSO-d6)
120575 16054 16036 15082 13756 13236 13225 13192 1201711946 11914 11846 11693 11648 Elemental Anal Calcd forC14H13NO2 C 7399 H 577 N 616 Found C 7281 H
564 N 616
N-(p-Chlorobenzylidene)-2-hydroxy-5-chloroaniline (2b)Mp 123ndash125∘C IR 3367 3086 3071 3059 2910 28941626 (C=N) 1588 1569 1478 1424 1370 1274 1234 11941154 1087 1011 911 857 815 799 (CndashCl) 697 658 608 548533 cmminus1 1H NMR (CDCl
3) 120575 866 (s 1H N=CH) 791
4 Organic Chemistry International
(d J = 84Hz 2H Ar) 754 (d J = 84Hz 2H Ar) 734(s 1H Ar) 724 (d J = 86Hz 1H Ar) 702 (d J = 86Hz1H Ar) 13C NMR (CDCl
3) 120575 15675 (N=C) 15094 13821
13586 13387 13006 12928 12877 12507 11619 11616Elemental Anal Calcd for C
13H9Cl2NO C 5867 H 341
N 526 Found C 5774 H 342 N 526
N-(p-Chlorobenzylidene)-2-hydroxy-4-methylaniline (3b)Mp 134ndash137∘C IR 3367 3063 3049 3028 2907 2857 1629(C=N) 1576 1569 1497 1370 1344 1295 1242 1169 11541080 1011 947 874 857 828 808 (CndashCl) 793 733 687 610591 579 cmminus1 1H NMR (CDCl
3) 120575 872 (s 1H N=CH) 792
(d J = 83Hz 2H Ar) 753 (d J = 84Hz 2H Ar) 729 (dJ = 81Hz 1H Ar) 692 (s 1H Ar) 680 (d J = 80Hz 1HAr) 242 (s 3H CH
3) 13C NMR (CDCl
3) 120575 15409 (N=C)
15234 13981 13740 13454 13260 12972 12916 1209311567 11536 2148 Elemental Anal Calcd for C
14H12ClNO
C 6844 H 492 N 570 Found C 6764 H 489 N 569
N-(p-Methoxybenzylidene)-2-hydroxy-5-chloroaniline (2c)Mp 86ndash88∘C IR 3323 3017 2970 2954 2927 2840 1626(C=N) 1599 1569 1511 1453 1312 1250 1165 1027 804 650594 cmminus1 1H NMR (CDCl
3) 120575 988 (s 1H OH) 855 (s 1H
N=CH) 785 (d J = 85Hz 2H Ar) 723 (s 1H Ar) 711 (dJ = 86Hz 1H Ar) 699 (d J = 85Hz 2H Ar) 690 (d J =86Hz 1H Ar) 388 (s 3H OCH
3) 13C NMR (CDCl
3) 120575
16292 15776 (N=C) 15070 13669 13085 12849 1278112491 11608 11577 11433 5549 Elemental Anal Calcd forC14H12ClNO
2 C 6425 H 462 N 535 Found C 6292 H
457 N 545
N-(p-Methoxybenzylidene)-2-hydroxy-4-methylaniline (3c)Mp 86ndash87∘C IR 3344 3066 3018 2974 2934 2907 28401622 (C=N) 1593 1567 1509 1481 1423 1378 1245 1162 1026969 909 861 835 809 761 666 617 559 cmminus1 1H NMR(CDCl
3) 120575 859 (s 1H N=CH) 783 (d J = 87Hz 2H Ar)
716 (d J = 81Hz 1H Ar) 697 (d J = 87Hz 2H Ar) 681(s 1H Ar) 668 (d J = 78Hz 1H Ar) 386 (s 3H OCH
3)
231 (s 3H CH3) 13CNMR (CDCl
3) 120575 16252 15525 (N=C)
15202 13871 13368 13036 12913 12074 11534 1152611430 5545 2141 Elemental Anal Calcd for C
15H15NO2
C 7467 H 627 N 581 Found C 7463 H 641 N 621
N-(Cinnamylidene)-2-hydroxy-5-chloroaniline (2d)Mp 91ndash93∘C IR 3344 3064 3013 2964 2911 2881 2839 1621 (C=N)1577 1501 1483 1445 1366 1240 1154 1082 979 837 804 742683 661 593 cmminus1 1H NMR (CDCl
3) 120575 841 (d J = 82Hz
1H N=CH) 754 (d J = 52 2H Ar) 743ndash700 (m 5H Aramp CH=CH) 729 (s 1H Ar) 722 (d J = 81Hz 1H Ar)690 (d J = 86Hz 1H Ar) 13C NMR (CDCl
3) 120575 15936
15095 (N=C) 14523 13647 13535 12999 12899 1283612811 12769 12494 11599 11586 Elemental Anal Calcd forC15H12ClNO C 6991 H 469 N 543 Found C 6880 H
472 N 536
N-(Cinnamylidene)-2-hydroxy-4-methylaniline (3d) Mp 97-98∘C IR 3350 3061 3012 2963 2912 2880 2840 1624(C=N) 1577 1541 1498 1447 1368 1257 1157 1092 975836 804 749 686 630 552 cmminus1 1H NMR (CDCl
3) 120575 857
(d J = 66Hz 1H N=CH) 766 (dd J = 60 19Hz 2H Ar)754ndash712 (m 5H Ar amp CH=CH) 730 (d J = 79Hz 1H Ar)693 (s 1H Ar) 680 (d J = 81Hz 1H Ar) 243 (s 3H Ar)13C NMR (CDCl
3) 120575 15685 15228 (N=C) 14326 13938
13571 13320 12953 12892 12873 12746 12075 1154811504 2146 Elemental Anal Calcd for C
16H15NO C 8098
H 637 N 526 Found C 7922 H 618 N 590
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank the Middle East TechnicalUniversity analysis Center (Turkiye) for elemental analysesand Ozgur Ozdamar (Assistant Professor) and Hasan Saral(Assistant Professor) for the analysis NMR and IR of someimine compounds
References
[1] A M Asiri and S A Khan ldquoSynthesis and anti-bacterial activ-ities of some novel schiff bases derived from aminophenazonerdquoMolecules vol 15 no 10 pp 6850ndash6858 2010
[2] R W Layer ldquoThe chemistry of iminesrdquo Chemical Reviews vol63 pp 489ndash510 1963
[3] H-K Fun R Kia A M Vijesh and A M Isloor ldquo5-Diethy-lamino-2-[(E)-(4-methyl-3-nitrophenyl)iminomethyl]phenol aredeterminationrdquo Acta Crystallographica E Structure ReportsOnline vol 65 no 2 pp o349ndasho350 2009
[4] H Schiff ldquoSur quelques derives pheniques des aldehydesrdquoAnnali Di Chimica vol 131 p 118 1864
[5] K Taguchi and F H Westheimer ldquoCatalysis by molecularsieves in the preparation of ketimines and enaminesrdquo Journalof Organic Chemistry vol 36 no 11 pp 1570ndash1572 1971
[6] M E Kuehne ldquoThe application of enamines to a new synthesisof 120573-ketonitrilesrdquo Journal of the American Chemical Society vol81 no 20 pp 5400ndash5404 1959
[7] M A Vazquez M Landa L Reyes R Miranda J Tamarizand F Delgado ldquoInfrared irradiation effective promoter in theformation of N-benzylideneanilines in the absence of solventrdquoSynthetic Communications vol 34 no 15 pp 2705ndash2718 2004
[8] A K Chakraborti S Bhagat and S Rudrawar ldquoMagnesiumperchlorate as an efficient catalyst for the synthesis of iminesand phenylhydrazonesrdquo Tetrahedron Letters vol 45 no 41 pp7641ndash7644 2004
[9] H Naeimi H Sharghi F Salimi and K Rabiei ldquoFacile andefficient method for preparation of Schiff bases catalyzed byP2O5SiO2under free Solvent conditionsrdquo Heteroatom Chem-
istry vol 19 no 1 pp 43ndash47 2008[10] J H Billman and K M Tai ldquoReduction of Schiff bases
II benzhydrylamines and structurally related compoundsrdquoJournal of Organic Chemistry vol 23 no 4 pp 535ndash539 1958
[11] M Gopalakrishnan P Sureshkumar V Kanagarajan and JThanusu ldquoNew environmentally-friendly solvent-free synthesisof imines using calcium oxide under microwave irradiationrdquoResearch on Chemical Intermediates vol 33 no 6 pp 541ndash5482007
Organic Chemistry International 5
[12] J S Bennett K L Charles M R Miner et al ldquoEthyl lactateas a tunable solvent for the synthesis of aryl aldiminesrdquo GreenChemistry vol 11 no 2 pp 166ndash168 2009
[13] R S Varma R Dahiya and S Kumar ldquoClay catalyzed synthesisof imines and enamines under solvent-free conditions usingmicrowave irradiationrdquo Tetrahedron Letters vol 38 no 12 pp2039ndash2042 1997
[14] W A White and H Weingarten ldquoA versatile new enaminesynthesisrdquo Journal of Organic Chemistry vol 32 no 1 pp 213ndash214 1967
[15] F Texier-Boullet ldquoA simple convenient and mild synthesis ofimines on alumina surface without solventrdquo Synthesis vol 1985no 6-7 pp 679ndash681 1985
[16] L Ravishankar S A Patwe N Gosarani and A RoyldquoCerium(III)-catalyzed synthesis of schiff bases a greenapproachrdquo Synthetic Communications vol 40 no 21 pp 3177ndash3180 2010
[17] K P Guzen A S Guarezemini A T G Orfao R Cella CM PPereira and H A Stefani ldquoEco-friendly synthesis of imines byultrasound irradiationrdquo Tetrahedron Letters vol 48 no 10 pp1845ndash1848 2007
[18] R Annunziata M Benaglia M Cinquini and F CozzildquoPoly(ethylene glycol)-supported 4-alkylthio-substituted ani-line a useful starting material for the soluble polymer-sup-ported synthesis of imines and 1234-tetrahydroquinolinesrdquoEuropean Journal of Organic Chemistry no 7 pp 1184ndash11902002
[19] M Hosseini-Sarvari ldquoNano-tube TiO2as a new catalyst for
eco-friendly synthesis of imines in sunlightrdquo Chinese ChemicalLetters vol 22 no 5 pp 547ndash550 2011
[20] G Dutheuil S Couve-Bonnaire and X Pannecoucke ldquoDias-tereomeric fluoroolefins as peptide bond mimics preparedby asymmetric reductive amination of 120572-fluoroenonesrdquo Ange-wandte Chemie International Edition vol 46 no 8 pp 1290ndash1292 2007
[21] J F Collados E Toledano D Guijarro and M Yus ldquoMicro-wave-assisted solvent-free synthesis of enantiomerically pureN-(tert-Butylsulfinyl)iminesrdquo Journal of Organic Chemistryvol 77 Article ID 300919 pp 5744ndash5750 2012
[22] E Tauer and K H Grellmann ldquoPhotochemical and thermalreactions of aromatic Schiff basesrdquo Journal of Organic Chem-istry vol 46 no 21 pp 4252ndash4258 1981
[23] R J Argauer and C E White ldquoEffect of substituent groups onfluorescence ofmetal chelatesrdquoAnalytical Chemistry vol 36 no11 pp 2141ndash2148 1964
[24] J D Margerum and J A Sousa ldquoSpectroscopic studies ofsubstituted benzalanilinesrdquoApplied Spectroscopy vol 19 pp 91ndash97 1965
[25] J E Kuder H W Gibson and D Wychick ldquoElectrochemicalcharacterization of salicylaldehyde anilsrdquo Journal of OrganicChemistry vol 40 no 7 pp 875ndash879 1975
[26] F F Stephens and J D Bower ldquoThe preparation of benzimina-zoles and benzoxazoles from Schiff rsquos bases Part Irdquo Journal of theChemical Society pp 2971ndash2972 1949
[27] J Schmeyers F Toda J Boy and G Kaupp ldquoQuantitative solid-solid synthesis of azomethinesrdquo Journal of the Chemical SocietyPerkin Transactions 2 no 4 pp 989ndash993 1998
[28] W Xu S Zhang S Yang et al ldquoAsymmetric synthesis of 120572-aminophosphonates using the inexpensive chiral catalyst 111015840-binaphthol phosphaterdquoMolecules vol 15 no 8 pp 5782ndash57962010
[29] Y M S A Al-Kahraman H M F Madkour D Ali andM Yasinzai ldquoAntileishmanial antimicrobial and antifungalactivities of some new aryl azomethinesrdquoMolecules vol 15 no2 pp 660ndash671 2010
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2 Organic Chemistry International
Ar
ArH
O
+ NH2 R
2
R1
R3
R2
R1
R3
Microwave N
(andashd) (1andash7d)(1ndash7)
Scheme 1
Table 1 The optimization of microwave conditions for compound1a
Microwave methodWatt Time (min) Reaction conditions Yield ()180 5 Wetting (with 120573-EE) 83360 5 Wetting (with 120573-EE) 93360 15 Wetting (with 120573-EE) 94360 5 Neat 88360 15 Neat 81
Table 2 The optimization of classical conditions for compound 1a
Classical methodTime (min) Yield () Reaction conditions30 64 Reflux60 73 Reflux120 76 Reflux240 75 Reflux1300lowast 74 RefluxProcedure 1mmol aldehyde (10mL of ethanol) and 1mmol amine (10mL ofethanol) are mixed a balloon and then boiled under reflux on a hot platelowast300min (heated) + 1000min (unheated)
(15min) were obtained at 360W microwave power with 120573-EE In the absence of wetting reagent the reaction yields are81 for 15 minutes and 88 for 5 minutes It is understoodthat the reaction yield was increased by wetting reagentthat increases the polarity of the reaction medium Theoptimization of microwave-assisted conditions was given inTable 1
In addition we have synthesized some imine derivatives(1a4a 1b4b 1c4c 1d4d) under classical conditions using asolvent (azeotropic) and traditional heating source (hot plate)for comparison with microwave conditions Firstly synthesisof compound 1a under the classical reaction conditions wastested at various periods of time (30 60 120 240 1300min) todetermine the optimumreaction timewhichwas determinedas 120 minutes Information on the optimization of thereaction time of compound 1a for classic conditions waspresented in Table 2
The compounds 1a 4a 1b 4b 1c 4c 1d and 4d wereobtained at 76 73 63 79 67 73 67 and75 yields respectively in 120 minutes under the classi-cal reaction conditions whereas in microwave conditions
0
20
40
60
80
100
Yiel
d (
)
Compound
MicrowaveClassical
1a 4b1b4a 4d1d4c1c
Figure 1 Comparison of yields under the microwave and classicalconditions
the corresponding reaction yields were 94 97 95 9891 97 95 and 96 respectively in 10ndash15 minutes Allthe results such as reactions time yields and melting pointsof the compounds were presented in Table 3 In addition theyields of microwave and conventional reaction conditions forsome imines were expressed graphically in Figure 1
3 Conclusion
In conclusion we have developed a simple microwaveassisted solvent-free method for the synthesis of imines usinga wetting reagent (120573-ethoxyethanol) The method workswell for the reaction of this type amines and aldehydesBecause we have synthesized imine compounds for goodyields and fast reaction times in our method Our methodhas some advances such as higher reaction yields shorterreaction times and green reaction conditions than classicalrequirements used of a solvent and conventional heat source(like hot plate) and other some microwave methods used ofcatalyst and solid supports In addition some imines weresynthesized for the first time by us with this study
4 Experimental
All of the chemicals were obtained from commercial sourcesor prepared according to standard methods Melting points
Organic Chemistry International 3
Table 3 Synthesis of imine derivatives under microwave irradiation
N Ar R1
R2
R3
Microwavea Classicalb mp ∘C Lit mp ∘CYield 119905min Yield 119905min
1a
OH
OH H H 94 15 76 120 188ndash190 190 [22]2a OH H Cl 93 15 mdash mdash 159ndash162 156ndash1565 [23]3a OH CH3 H 93 15 mdash mdash 199ndash202 mdash4a H H H 97 10 73 120 50ndash53 50-51 [24]5a H Cl H 94 15 mdash mdash 103ndash105 104 [12]6a H CH3O H 96 15 mdash mdash 83ndash85 82ndash835 [25]7a H CH3 H 97 15 mdash mdash 93-94 90ndash915 [25]1b
Cl
OH H H 95 15 63 120 116ndash118 117 [26]2b OH H Cl 92 20 mdash mdash 123ndash125 mdash3b OH CH3 H 91 20 mdash mdash 134ndash137 mdash4b H H H 98 10 79 120 63ndash66 64-65 [24]5b H Cl H 94 15 mdash mdash 110-111 110-111 [24]6b H CH3O H 91 30 mdash mdash 124ndash126 124-125 [27]7b H CH3 H 93 15 mdash mdash 126ndash128 125 [27]1c
H3CO
OH H H 91 15 67 120 90-91 91ndash93 [22]2c OH H Cl 95 10 mdash mdash 86ndash88 mdash3c OH CH3 H 93 15 mdash mdash 86-87 mdash4c H H H 97 10 73 120 58ndash60 63ndash635 [24]5c H Cl H 97 15 mdash mdash 90ndash92 92 [16]6c H CH3O H 95 15 mdash mdash 147ndash149 145-146 [24]7c H CH3 H 91 15 mdash mdash 92-93 91-92 [24]1d OH H H 95 15 67 120 89ndash91 92 [22]2d OH H Cl 91 15 mdash mdash 91ndash93 mdash3d OH CH3 H 94 15 mdash mdash 97-98 mdash4d H H H 96 10 75 120 108ndash111 108-109 [12]5d H Cl H 96 15 mdash mdash 105ndash107 105 [12]6d H CH3O H 97 15 mdash mdash 120-121 119-120 [12]7d H CH3 H 90 15 mdash mdash 75ndash77 76-77 [28 29]aUnder solvent-free reaction using microwavebProcedure 1mmol aldehyde (10mL of ethanol) and 1mmol amine (10mL of ethanol) are mixed a balloon and then boiled under reflux on a hot plate
were determined with an Electrothermal 9100 apparatusThe infrared absorption spectrum of the compounds hasbeen recorded in the region at 4000 and 400 cmminus1 rangeusing a Bruker Vertex 8080 v spectrophotometer using KBrpressed pellet technique at room temperature The 1H NMRand 13C NMR spectra were recorded using a Bruker AC200NMR 200MHz spectrometer in CDCl
3-1198891and DMSO-
1198896using TMS as the internal standard Elemental analyses
were conducted at the METU Central Laboratory using aLECO CHNS-932 All syntheses were carried out in A BoshHMT 812C modified microwave oven
General Procedure for Preparation of 1andash7d Aldehyde(1mmoL) amine (1mmoL) and two drops of 120573-ethox-yethanol as awetting reagentweremixed in a beakerThen thebeaker was placed in the microwave oven and was exposedto microwave irradiation (360W) The product obtainedby reaction was washed with cold ethanol Then it was
recrystallized in ethanolThe physical and spectra data of thecompounds 3a 2b 3b 2c 3c 2d and 3d are as follows
N-(Salicylidene)-2-hydroxy-4-methylaniline (3a) Mp 199-202∘C IR 3033 2965 2916 2858 1612 (C=N) 1592 15271486 1422 1278 1221 1141 1113 1012 869 788 754 720 622587 556 cmminus1 1H NMR (DMSO-d
6) 120575 894 (s 1H N=CH)
1390 (s 1H OH) 965 (s 1H OH) 13C NMR (DMSO-d6)
120575 16054 16036 15082 13756 13236 13225 13192 1201711946 11914 11846 11693 11648 Elemental Anal Calcd forC14H13NO2 C 7399 H 577 N 616 Found C 7281 H
564 N 616
N-(p-Chlorobenzylidene)-2-hydroxy-5-chloroaniline (2b)Mp 123ndash125∘C IR 3367 3086 3071 3059 2910 28941626 (C=N) 1588 1569 1478 1424 1370 1274 1234 11941154 1087 1011 911 857 815 799 (CndashCl) 697 658 608 548533 cmminus1 1H NMR (CDCl
3) 120575 866 (s 1H N=CH) 791
4 Organic Chemistry International
(d J = 84Hz 2H Ar) 754 (d J = 84Hz 2H Ar) 734(s 1H Ar) 724 (d J = 86Hz 1H Ar) 702 (d J = 86Hz1H Ar) 13C NMR (CDCl
3) 120575 15675 (N=C) 15094 13821
13586 13387 13006 12928 12877 12507 11619 11616Elemental Anal Calcd for C
13H9Cl2NO C 5867 H 341
N 526 Found C 5774 H 342 N 526
N-(p-Chlorobenzylidene)-2-hydroxy-4-methylaniline (3b)Mp 134ndash137∘C IR 3367 3063 3049 3028 2907 2857 1629(C=N) 1576 1569 1497 1370 1344 1295 1242 1169 11541080 1011 947 874 857 828 808 (CndashCl) 793 733 687 610591 579 cmminus1 1H NMR (CDCl
3) 120575 872 (s 1H N=CH) 792
(d J = 83Hz 2H Ar) 753 (d J = 84Hz 2H Ar) 729 (dJ = 81Hz 1H Ar) 692 (s 1H Ar) 680 (d J = 80Hz 1HAr) 242 (s 3H CH
3) 13C NMR (CDCl
3) 120575 15409 (N=C)
15234 13981 13740 13454 13260 12972 12916 1209311567 11536 2148 Elemental Anal Calcd for C
14H12ClNO
C 6844 H 492 N 570 Found C 6764 H 489 N 569
N-(p-Methoxybenzylidene)-2-hydroxy-5-chloroaniline (2c)Mp 86ndash88∘C IR 3323 3017 2970 2954 2927 2840 1626(C=N) 1599 1569 1511 1453 1312 1250 1165 1027 804 650594 cmminus1 1H NMR (CDCl
3) 120575 988 (s 1H OH) 855 (s 1H
N=CH) 785 (d J = 85Hz 2H Ar) 723 (s 1H Ar) 711 (dJ = 86Hz 1H Ar) 699 (d J = 85Hz 2H Ar) 690 (d J =86Hz 1H Ar) 388 (s 3H OCH
3) 13C NMR (CDCl
3) 120575
16292 15776 (N=C) 15070 13669 13085 12849 1278112491 11608 11577 11433 5549 Elemental Anal Calcd forC14H12ClNO
2 C 6425 H 462 N 535 Found C 6292 H
457 N 545
N-(p-Methoxybenzylidene)-2-hydroxy-4-methylaniline (3c)Mp 86ndash87∘C IR 3344 3066 3018 2974 2934 2907 28401622 (C=N) 1593 1567 1509 1481 1423 1378 1245 1162 1026969 909 861 835 809 761 666 617 559 cmminus1 1H NMR(CDCl
3) 120575 859 (s 1H N=CH) 783 (d J = 87Hz 2H Ar)
716 (d J = 81Hz 1H Ar) 697 (d J = 87Hz 2H Ar) 681(s 1H Ar) 668 (d J = 78Hz 1H Ar) 386 (s 3H OCH
3)
231 (s 3H CH3) 13CNMR (CDCl
3) 120575 16252 15525 (N=C)
15202 13871 13368 13036 12913 12074 11534 1152611430 5545 2141 Elemental Anal Calcd for C
15H15NO2
C 7467 H 627 N 581 Found C 7463 H 641 N 621
N-(Cinnamylidene)-2-hydroxy-5-chloroaniline (2d)Mp 91ndash93∘C IR 3344 3064 3013 2964 2911 2881 2839 1621 (C=N)1577 1501 1483 1445 1366 1240 1154 1082 979 837 804 742683 661 593 cmminus1 1H NMR (CDCl
3) 120575 841 (d J = 82Hz
1H N=CH) 754 (d J = 52 2H Ar) 743ndash700 (m 5H Aramp CH=CH) 729 (s 1H Ar) 722 (d J = 81Hz 1H Ar)690 (d J = 86Hz 1H Ar) 13C NMR (CDCl
3) 120575 15936
15095 (N=C) 14523 13647 13535 12999 12899 1283612811 12769 12494 11599 11586 Elemental Anal Calcd forC15H12ClNO C 6991 H 469 N 543 Found C 6880 H
472 N 536
N-(Cinnamylidene)-2-hydroxy-4-methylaniline (3d) Mp 97-98∘C IR 3350 3061 3012 2963 2912 2880 2840 1624(C=N) 1577 1541 1498 1447 1368 1257 1157 1092 975836 804 749 686 630 552 cmminus1 1H NMR (CDCl
3) 120575 857
(d J = 66Hz 1H N=CH) 766 (dd J = 60 19Hz 2H Ar)754ndash712 (m 5H Ar amp CH=CH) 730 (d J = 79Hz 1H Ar)693 (s 1H Ar) 680 (d J = 81Hz 1H Ar) 243 (s 3H Ar)13C NMR (CDCl
3) 120575 15685 15228 (N=C) 14326 13938
13571 13320 12953 12892 12873 12746 12075 1154811504 2146 Elemental Anal Calcd for C
16H15NO C 8098
H 637 N 526 Found C 7922 H 618 N 590
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank the Middle East TechnicalUniversity analysis Center (Turkiye) for elemental analysesand Ozgur Ozdamar (Assistant Professor) and Hasan Saral(Assistant Professor) for the analysis NMR and IR of someimine compounds
References
[1] A M Asiri and S A Khan ldquoSynthesis and anti-bacterial activ-ities of some novel schiff bases derived from aminophenazonerdquoMolecules vol 15 no 10 pp 6850ndash6858 2010
[2] R W Layer ldquoThe chemistry of iminesrdquo Chemical Reviews vol63 pp 489ndash510 1963
[3] H-K Fun R Kia A M Vijesh and A M Isloor ldquo5-Diethy-lamino-2-[(E)-(4-methyl-3-nitrophenyl)iminomethyl]phenol aredeterminationrdquo Acta Crystallographica E Structure ReportsOnline vol 65 no 2 pp o349ndasho350 2009
[4] H Schiff ldquoSur quelques derives pheniques des aldehydesrdquoAnnali Di Chimica vol 131 p 118 1864
[5] K Taguchi and F H Westheimer ldquoCatalysis by molecularsieves in the preparation of ketimines and enaminesrdquo Journalof Organic Chemistry vol 36 no 11 pp 1570ndash1572 1971
[6] M E Kuehne ldquoThe application of enamines to a new synthesisof 120573-ketonitrilesrdquo Journal of the American Chemical Society vol81 no 20 pp 5400ndash5404 1959
[7] M A Vazquez M Landa L Reyes R Miranda J Tamarizand F Delgado ldquoInfrared irradiation effective promoter in theformation of N-benzylideneanilines in the absence of solventrdquoSynthetic Communications vol 34 no 15 pp 2705ndash2718 2004
[8] A K Chakraborti S Bhagat and S Rudrawar ldquoMagnesiumperchlorate as an efficient catalyst for the synthesis of iminesand phenylhydrazonesrdquo Tetrahedron Letters vol 45 no 41 pp7641ndash7644 2004
[9] H Naeimi H Sharghi F Salimi and K Rabiei ldquoFacile andefficient method for preparation of Schiff bases catalyzed byP2O5SiO2under free Solvent conditionsrdquo Heteroatom Chem-
istry vol 19 no 1 pp 43ndash47 2008[10] J H Billman and K M Tai ldquoReduction of Schiff bases
II benzhydrylamines and structurally related compoundsrdquoJournal of Organic Chemistry vol 23 no 4 pp 535ndash539 1958
[11] M Gopalakrishnan P Sureshkumar V Kanagarajan and JThanusu ldquoNew environmentally-friendly solvent-free synthesisof imines using calcium oxide under microwave irradiationrdquoResearch on Chemical Intermediates vol 33 no 6 pp 541ndash5482007
Organic Chemistry International 5
[12] J S Bennett K L Charles M R Miner et al ldquoEthyl lactateas a tunable solvent for the synthesis of aryl aldiminesrdquo GreenChemistry vol 11 no 2 pp 166ndash168 2009
[13] R S Varma R Dahiya and S Kumar ldquoClay catalyzed synthesisof imines and enamines under solvent-free conditions usingmicrowave irradiationrdquo Tetrahedron Letters vol 38 no 12 pp2039ndash2042 1997
[14] W A White and H Weingarten ldquoA versatile new enaminesynthesisrdquo Journal of Organic Chemistry vol 32 no 1 pp 213ndash214 1967
[15] F Texier-Boullet ldquoA simple convenient and mild synthesis ofimines on alumina surface without solventrdquo Synthesis vol 1985no 6-7 pp 679ndash681 1985
[16] L Ravishankar S A Patwe N Gosarani and A RoyldquoCerium(III)-catalyzed synthesis of schiff bases a greenapproachrdquo Synthetic Communications vol 40 no 21 pp 3177ndash3180 2010
[17] K P Guzen A S Guarezemini A T G Orfao R Cella CM PPereira and H A Stefani ldquoEco-friendly synthesis of imines byultrasound irradiationrdquo Tetrahedron Letters vol 48 no 10 pp1845ndash1848 2007
[18] R Annunziata M Benaglia M Cinquini and F CozzildquoPoly(ethylene glycol)-supported 4-alkylthio-substituted ani-line a useful starting material for the soluble polymer-sup-ported synthesis of imines and 1234-tetrahydroquinolinesrdquoEuropean Journal of Organic Chemistry no 7 pp 1184ndash11902002
[19] M Hosseini-Sarvari ldquoNano-tube TiO2as a new catalyst for
eco-friendly synthesis of imines in sunlightrdquo Chinese ChemicalLetters vol 22 no 5 pp 547ndash550 2011
[20] G Dutheuil S Couve-Bonnaire and X Pannecoucke ldquoDias-tereomeric fluoroolefins as peptide bond mimics preparedby asymmetric reductive amination of 120572-fluoroenonesrdquo Ange-wandte Chemie International Edition vol 46 no 8 pp 1290ndash1292 2007
[21] J F Collados E Toledano D Guijarro and M Yus ldquoMicro-wave-assisted solvent-free synthesis of enantiomerically pureN-(tert-Butylsulfinyl)iminesrdquo Journal of Organic Chemistryvol 77 Article ID 300919 pp 5744ndash5750 2012
[22] E Tauer and K H Grellmann ldquoPhotochemical and thermalreactions of aromatic Schiff basesrdquo Journal of Organic Chem-istry vol 46 no 21 pp 4252ndash4258 1981
[23] R J Argauer and C E White ldquoEffect of substituent groups onfluorescence ofmetal chelatesrdquoAnalytical Chemistry vol 36 no11 pp 2141ndash2148 1964
[24] J D Margerum and J A Sousa ldquoSpectroscopic studies ofsubstituted benzalanilinesrdquoApplied Spectroscopy vol 19 pp 91ndash97 1965
[25] J E Kuder H W Gibson and D Wychick ldquoElectrochemicalcharacterization of salicylaldehyde anilsrdquo Journal of OrganicChemistry vol 40 no 7 pp 875ndash879 1975
[26] F F Stephens and J D Bower ldquoThe preparation of benzimina-zoles and benzoxazoles from Schiff rsquos bases Part Irdquo Journal of theChemical Society pp 2971ndash2972 1949
[27] J Schmeyers F Toda J Boy and G Kaupp ldquoQuantitative solid-solid synthesis of azomethinesrdquo Journal of the Chemical SocietyPerkin Transactions 2 no 4 pp 989ndash993 1998
[28] W Xu S Zhang S Yang et al ldquoAsymmetric synthesis of 120572-aminophosphonates using the inexpensive chiral catalyst 111015840-binaphthol phosphaterdquoMolecules vol 15 no 8 pp 5782ndash57962010
[29] Y M S A Al-Kahraman H M F Madkour D Ali andM Yasinzai ldquoAntileishmanial antimicrobial and antifungalactivities of some new aryl azomethinesrdquoMolecules vol 15 no2 pp 660ndash671 2010
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
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Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
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Analytical Methods in Chemistry
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Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom
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Analytical ChemistryVolume 2014
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Quantum Chemistry
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Organic Chemistry International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Organic Chemistry International 3
Table 3 Synthesis of imine derivatives under microwave irradiation
N Ar R1
R2
R3
Microwavea Classicalb mp ∘C Lit mp ∘CYield 119905min Yield 119905min
1a
OH
OH H H 94 15 76 120 188ndash190 190 [22]2a OH H Cl 93 15 mdash mdash 159ndash162 156ndash1565 [23]3a OH CH3 H 93 15 mdash mdash 199ndash202 mdash4a H H H 97 10 73 120 50ndash53 50-51 [24]5a H Cl H 94 15 mdash mdash 103ndash105 104 [12]6a H CH3O H 96 15 mdash mdash 83ndash85 82ndash835 [25]7a H CH3 H 97 15 mdash mdash 93-94 90ndash915 [25]1b
Cl
OH H H 95 15 63 120 116ndash118 117 [26]2b OH H Cl 92 20 mdash mdash 123ndash125 mdash3b OH CH3 H 91 20 mdash mdash 134ndash137 mdash4b H H H 98 10 79 120 63ndash66 64-65 [24]5b H Cl H 94 15 mdash mdash 110-111 110-111 [24]6b H CH3O H 91 30 mdash mdash 124ndash126 124-125 [27]7b H CH3 H 93 15 mdash mdash 126ndash128 125 [27]1c
H3CO
OH H H 91 15 67 120 90-91 91ndash93 [22]2c OH H Cl 95 10 mdash mdash 86ndash88 mdash3c OH CH3 H 93 15 mdash mdash 86-87 mdash4c H H H 97 10 73 120 58ndash60 63ndash635 [24]5c H Cl H 97 15 mdash mdash 90ndash92 92 [16]6c H CH3O H 95 15 mdash mdash 147ndash149 145-146 [24]7c H CH3 H 91 15 mdash mdash 92-93 91-92 [24]1d OH H H 95 15 67 120 89ndash91 92 [22]2d OH H Cl 91 15 mdash mdash 91ndash93 mdash3d OH CH3 H 94 15 mdash mdash 97-98 mdash4d H H H 96 10 75 120 108ndash111 108-109 [12]5d H Cl H 96 15 mdash mdash 105ndash107 105 [12]6d H CH3O H 97 15 mdash mdash 120-121 119-120 [12]7d H CH3 H 90 15 mdash mdash 75ndash77 76-77 [28 29]aUnder solvent-free reaction using microwavebProcedure 1mmol aldehyde (10mL of ethanol) and 1mmol amine (10mL of ethanol) are mixed a balloon and then boiled under reflux on a hot plate
were determined with an Electrothermal 9100 apparatusThe infrared absorption spectrum of the compounds hasbeen recorded in the region at 4000 and 400 cmminus1 rangeusing a Bruker Vertex 8080 v spectrophotometer using KBrpressed pellet technique at room temperature The 1H NMRand 13C NMR spectra were recorded using a Bruker AC200NMR 200MHz spectrometer in CDCl
3-1198891and DMSO-
1198896using TMS as the internal standard Elemental analyses
were conducted at the METU Central Laboratory using aLECO CHNS-932 All syntheses were carried out in A BoshHMT 812C modified microwave oven
General Procedure for Preparation of 1andash7d Aldehyde(1mmoL) amine (1mmoL) and two drops of 120573-ethox-yethanol as awetting reagentweremixed in a beakerThen thebeaker was placed in the microwave oven and was exposedto microwave irradiation (360W) The product obtainedby reaction was washed with cold ethanol Then it was
recrystallized in ethanolThe physical and spectra data of thecompounds 3a 2b 3b 2c 3c 2d and 3d are as follows
N-(Salicylidene)-2-hydroxy-4-methylaniline (3a) Mp 199-202∘C IR 3033 2965 2916 2858 1612 (C=N) 1592 15271486 1422 1278 1221 1141 1113 1012 869 788 754 720 622587 556 cmminus1 1H NMR (DMSO-d
6) 120575 894 (s 1H N=CH)
1390 (s 1H OH) 965 (s 1H OH) 13C NMR (DMSO-d6)
120575 16054 16036 15082 13756 13236 13225 13192 1201711946 11914 11846 11693 11648 Elemental Anal Calcd forC14H13NO2 C 7399 H 577 N 616 Found C 7281 H
564 N 616
N-(p-Chlorobenzylidene)-2-hydroxy-5-chloroaniline (2b)Mp 123ndash125∘C IR 3367 3086 3071 3059 2910 28941626 (C=N) 1588 1569 1478 1424 1370 1274 1234 11941154 1087 1011 911 857 815 799 (CndashCl) 697 658 608 548533 cmminus1 1H NMR (CDCl
3) 120575 866 (s 1H N=CH) 791
4 Organic Chemistry International
(d J = 84Hz 2H Ar) 754 (d J = 84Hz 2H Ar) 734(s 1H Ar) 724 (d J = 86Hz 1H Ar) 702 (d J = 86Hz1H Ar) 13C NMR (CDCl
3) 120575 15675 (N=C) 15094 13821
13586 13387 13006 12928 12877 12507 11619 11616Elemental Anal Calcd for C
13H9Cl2NO C 5867 H 341
N 526 Found C 5774 H 342 N 526
N-(p-Chlorobenzylidene)-2-hydroxy-4-methylaniline (3b)Mp 134ndash137∘C IR 3367 3063 3049 3028 2907 2857 1629(C=N) 1576 1569 1497 1370 1344 1295 1242 1169 11541080 1011 947 874 857 828 808 (CndashCl) 793 733 687 610591 579 cmminus1 1H NMR (CDCl
3) 120575 872 (s 1H N=CH) 792
(d J = 83Hz 2H Ar) 753 (d J = 84Hz 2H Ar) 729 (dJ = 81Hz 1H Ar) 692 (s 1H Ar) 680 (d J = 80Hz 1HAr) 242 (s 3H CH
3) 13C NMR (CDCl
3) 120575 15409 (N=C)
15234 13981 13740 13454 13260 12972 12916 1209311567 11536 2148 Elemental Anal Calcd for C
14H12ClNO
C 6844 H 492 N 570 Found C 6764 H 489 N 569
N-(p-Methoxybenzylidene)-2-hydroxy-5-chloroaniline (2c)Mp 86ndash88∘C IR 3323 3017 2970 2954 2927 2840 1626(C=N) 1599 1569 1511 1453 1312 1250 1165 1027 804 650594 cmminus1 1H NMR (CDCl
3) 120575 988 (s 1H OH) 855 (s 1H
N=CH) 785 (d J = 85Hz 2H Ar) 723 (s 1H Ar) 711 (dJ = 86Hz 1H Ar) 699 (d J = 85Hz 2H Ar) 690 (d J =86Hz 1H Ar) 388 (s 3H OCH
3) 13C NMR (CDCl
3) 120575
16292 15776 (N=C) 15070 13669 13085 12849 1278112491 11608 11577 11433 5549 Elemental Anal Calcd forC14H12ClNO
2 C 6425 H 462 N 535 Found C 6292 H
457 N 545
N-(p-Methoxybenzylidene)-2-hydroxy-4-methylaniline (3c)Mp 86ndash87∘C IR 3344 3066 3018 2974 2934 2907 28401622 (C=N) 1593 1567 1509 1481 1423 1378 1245 1162 1026969 909 861 835 809 761 666 617 559 cmminus1 1H NMR(CDCl
3) 120575 859 (s 1H N=CH) 783 (d J = 87Hz 2H Ar)
716 (d J = 81Hz 1H Ar) 697 (d J = 87Hz 2H Ar) 681(s 1H Ar) 668 (d J = 78Hz 1H Ar) 386 (s 3H OCH
3)
231 (s 3H CH3) 13CNMR (CDCl
3) 120575 16252 15525 (N=C)
15202 13871 13368 13036 12913 12074 11534 1152611430 5545 2141 Elemental Anal Calcd for C
15H15NO2
C 7467 H 627 N 581 Found C 7463 H 641 N 621
N-(Cinnamylidene)-2-hydroxy-5-chloroaniline (2d)Mp 91ndash93∘C IR 3344 3064 3013 2964 2911 2881 2839 1621 (C=N)1577 1501 1483 1445 1366 1240 1154 1082 979 837 804 742683 661 593 cmminus1 1H NMR (CDCl
3) 120575 841 (d J = 82Hz
1H N=CH) 754 (d J = 52 2H Ar) 743ndash700 (m 5H Aramp CH=CH) 729 (s 1H Ar) 722 (d J = 81Hz 1H Ar)690 (d J = 86Hz 1H Ar) 13C NMR (CDCl
3) 120575 15936
15095 (N=C) 14523 13647 13535 12999 12899 1283612811 12769 12494 11599 11586 Elemental Anal Calcd forC15H12ClNO C 6991 H 469 N 543 Found C 6880 H
472 N 536
N-(Cinnamylidene)-2-hydroxy-4-methylaniline (3d) Mp 97-98∘C IR 3350 3061 3012 2963 2912 2880 2840 1624(C=N) 1577 1541 1498 1447 1368 1257 1157 1092 975836 804 749 686 630 552 cmminus1 1H NMR (CDCl
3) 120575 857
(d J = 66Hz 1H N=CH) 766 (dd J = 60 19Hz 2H Ar)754ndash712 (m 5H Ar amp CH=CH) 730 (d J = 79Hz 1H Ar)693 (s 1H Ar) 680 (d J = 81Hz 1H Ar) 243 (s 3H Ar)13C NMR (CDCl
3) 120575 15685 15228 (N=C) 14326 13938
13571 13320 12953 12892 12873 12746 12075 1154811504 2146 Elemental Anal Calcd for C
16H15NO C 8098
H 637 N 526 Found C 7922 H 618 N 590
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank the Middle East TechnicalUniversity analysis Center (Turkiye) for elemental analysesand Ozgur Ozdamar (Assistant Professor) and Hasan Saral(Assistant Professor) for the analysis NMR and IR of someimine compounds
References
[1] A M Asiri and S A Khan ldquoSynthesis and anti-bacterial activ-ities of some novel schiff bases derived from aminophenazonerdquoMolecules vol 15 no 10 pp 6850ndash6858 2010
[2] R W Layer ldquoThe chemistry of iminesrdquo Chemical Reviews vol63 pp 489ndash510 1963
[3] H-K Fun R Kia A M Vijesh and A M Isloor ldquo5-Diethy-lamino-2-[(E)-(4-methyl-3-nitrophenyl)iminomethyl]phenol aredeterminationrdquo Acta Crystallographica E Structure ReportsOnline vol 65 no 2 pp o349ndasho350 2009
[4] H Schiff ldquoSur quelques derives pheniques des aldehydesrdquoAnnali Di Chimica vol 131 p 118 1864
[5] K Taguchi and F H Westheimer ldquoCatalysis by molecularsieves in the preparation of ketimines and enaminesrdquo Journalof Organic Chemistry vol 36 no 11 pp 1570ndash1572 1971
[6] M E Kuehne ldquoThe application of enamines to a new synthesisof 120573-ketonitrilesrdquo Journal of the American Chemical Society vol81 no 20 pp 5400ndash5404 1959
[7] M A Vazquez M Landa L Reyes R Miranda J Tamarizand F Delgado ldquoInfrared irradiation effective promoter in theformation of N-benzylideneanilines in the absence of solventrdquoSynthetic Communications vol 34 no 15 pp 2705ndash2718 2004
[8] A K Chakraborti S Bhagat and S Rudrawar ldquoMagnesiumperchlorate as an efficient catalyst for the synthesis of iminesand phenylhydrazonesrdquo Tetrahedron Letters vol 45 no 41 pp7641ndash7644 2004
[9] H Naeimi H Sharghi F Salimi and K Rabiei ldquoFacile andefficient method for preparation of Schiff bases catalyzed byP2O5SiO2under free Solvent conditionsrdquo Heteroatom Chem-
istry vol 19 no 1 pp 43ndash47 2008[10] J H Billman and K M Tai ldquoReduction of Schiff bases
II benzhydrylamines and structurally related compoundsrdquoJournal of Organic Chemistry vol 23 no 4 pp 535ndash539 1958
[11] M Gopalakrishnan P Sureshkumar V Kanagarajan and JThanusu ldquoNew environmentally-friendly solvent-free synthesisof imines using calcium oxide under microwave irradiationrdquoResearch on Chemical Intermediates vol 33 no 6 pp 541ndash5482007
Organic Chemistry International 5
[12] J S Bennett K L Charles M R Miner et al ldquoEthyl lactateas a tunable solvent for the synthesis of aryl aldiminesrdquo GreenChemistry vol 11 no 2 pp 166ndash168 2009
[13] R S Varma R Dahiya and S Kumar ldquoClay catalyzed synthesisof imines and enamines under solvent-free conditions usingmicrowave irradiationrdquo Tetrahedron Letters vol 38 no 12 pp2039ndash2042 1997
[14] W A White and H Weingarten ldquoA versatile new enaminesynthesisrdquo Journal of Organic Chemistry vol 32 no 1 pp 213ndash214 1967
[15] F Texier-Boullet ldquoA simple convenient and mild synthesis ofimines on alumina surface without solventrdquo Synthesis vol 1985no 6-7 pp 679ndash681 1985
[16] L Ravishankar S A Patwe N Gosarani and A RoyldquoCerium(III)-catalyzed synthesis of schiff bases a greenapproachrdquo Synthetic Communications vol 40 no 21 pp 3177ndash3180 2010
[17] K P Guzen A S Guarezemini A T G Orfao R Cella CM PPereira and H A Stefani ldquoEco-friendly synthesis of imines byultrasound irradiationrdquo Tetrahedron Letters vol 48 no 10 pp1845ndash1848 2007
[18] R Annunziata M Benaglia M Cinquini and F CozzildquoPoly(ethylene glycol)-supported 4-alkylthio-substituted ani-line a useful starting material for the soluble polymer-sup-ported synthesis of imines and 1234-tetrahydroquinolinesrdquoEuropean Journal of Organic Chemistry no 7 pp 1184ndash11902002
[19] M Hosseini-Sarvari ldquoNano-tube TiO2as a new catalyst for
eco-friendly synthesis of imines in sunlightrdquo Chinese ChemicalLetters vol 22 no 5 pp 547ndash550 2011
[20] G Dutheuil S Couve-Bonnaire and X Pannecoucke ldquoDias-tereomeric fluoroolefins as peptide bond mimics preparedby asymmetric reductive amination of 120572-fluoroenonesrdquo Ange-wandte Chemie International Edition vol 46 no 8 pp 1290ndash1292 2007
[21] J F Collados E Toledano D Guijarro and M Yus ldquoMicro-wave-assisted solvent-free synthesis of enantiomerically pureN-(tert-Butylsulfinyl)iminesrdquo Journal of Organic Chemistryvol 77 Article ID 300919 pp 5744ndash5750 2012
[22] E Tauer and K H Grellmann ldquoPhotochemical and thermalreactions of aromatic Schiff basesrdquo Journal of Organic Chem-istry vol 46 no 21 pp 4252ndash4258 1981
[23] R J Argauer and C E White ldquoEffect of substituent groups onfluorescence ofmetal chelatesrdquoAnalytical Chemistry vol 36 no11 pp 2141ndash2148 1964
[24] J D Margerum and J A Sousa ldquoSpectroscopic studies ofsubstituted benzalanilinesrdquoApplied Spectroscopy vol 19 pp 91ndash97 1965
[25] J E Kuder H W Gibson and D Wychick ldquoElectrochemicalcharacterization of salicylaldehyde anilsrdquo Journal of OrganicChemistry vol 40 no 7 pp 875ndash879 1975
[26] F F Stephens and J D Bower ldquoThe preparation of benzimina-zoles and benzoxazoles from Schiff rsquos bases Part Irdquo Journal of theChemical Society pp 2971ndash2972 1949
[27] J Schmeyers F Toda J Boy and G Kaupp ldquoQuantitative solid-solid synthesis of azomethinesrdquo Journal of the Chemical SocietyPerkin Transactions 2 no 4 pp 989ndash993 1998
[28] W Xu S Zhang S Yang et al ldquoAsymmetric synthesis of 120572-aminophosphonates using the inexpensive chiral catalyst 111015840-binaphthol phosphaterdquoMolecules vol 15 no 8 pp 5782ndash57962010
[29] Y M S A Al-Kahraman H M F Madkour D Ali andM Yasinzai ldquoAntileishmanial antimicrobial and antifungalactivities of some new aryl azomethinesrdquoMolecules vol 15 no2 pp 660ndash671 2010
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Hindawi Publishing Corporationhttpwwwhindawicom
International Journal of
Analytical ChemistryVolume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
4 Organic Chemistry International
(d J = 84Hz 2H Ar) 754 (d J = 84Hz 2H Ar) 734(s 1H Ar) 724 (d J = 86Hz 1H Ar) 702 (d J = 86Hz1H Ar) 13C NMR (CDCl
3) 120575 15675 (N=C) 15094 13821
13586 13387 13006 12928 12877 12507 11619 11616Elemental Anal Calcd for C
13H9Cl2NO C 5867 H 341
N 526 Found C 5774 H 342 N 526
N-(p-Chlorobenzylidene)-2-hydroxy-4-methylaniline (3b)Mp 134ndash137∘C IR 3367 3063 3049 3028 2907 2857 1629(C=N) 1576 1569 1497 1370 1344 1295 1242 1169 11541080 1011 947 874 857 828 808 (CndashCl) 793 733 687 610591 579 cmminus1 1H NMR (CDCl
3) 120575 872 (s 1H N=CH) 792
(d J = 83Hz 2H Ar) 753 (d J = 84Hz 2H Ar) 729 (dJ = 81Hz 1H Ar) 692 (s 1H Ar) 680 (d J = 80Hz 1HAr) 242 (s 3H CH
3) 13C NMR (CDCl
3) 120575 15409 (N=C)
15234 13981 13740 13454 13260 12972 12916 1209311567 11536 2148 Elemental Anal Calcd for C
14H12ClNO
C 6844 H 492 N 570 Found C 6764 H 489 N 569
N-(p-Methoxybenzylidene)-2-hydroxy-5-chloroaniline (2c)Mp 86ndash88∘C IR 3323 3017 2970 2954 2927 2840 1626(C=N) 1599 1569 1511 1453 1312 1250 1165 1027 804 650594 cmminus1 1H NMR (CDCl
3) 120575 988 (s 1H OH) 855 (s 1H
N=CH) 785 (d J = 85Hz 2H Ar) 723 (s 1H Ar) 711 (dJ = 86Hz 1H Ar) 699 (d J = 85Hz 2H Ar) 690 (d J =86Hz 1H Ar) 388 (s 3H OCH
3) 13C NMR (CDCl
3) 120575
16292 15776 (N=C) 15070 13669 13085 12849 1278112491 11608 11577 11433 5549 Elemental Anal Calcd forC14H12ClNO
2 C 6425 H 462 N 535 Found C 6292 H
457 N 545
N-(p-Methoxybenzylidene)-2-hydroxy-4-methylaniline (3c)Mp 86ndash87∘C IR 3344 3066 3018 2974 2934 2907 28401622 (C=N) 1593 1567 1509 1481 1423 1378 1245 1162 1026969 909 861 835 809 761 666 617 559 cmminus1 1H NMR(CDCl
3) 120575 859 (s 1H N=CH) 783 (d J = 87Hz 2H Ar)
716 (d J = 81Hz 1H Ar) 697 (d J = 87Hz 2H Ar) 681(s 1H Ar) 668 (d J = 78Hz 1H Ar) 386 (s 3H OCH
3)
231 (s 3H CH3) 13CNMR (CDCl
3) 120575 16252 15525 (N=C)
15202 13871 13368 13036 12913 12074 11534 1152611430 5545 2141 Elemental Anal Calcd for C
15H15NO2
C 7467 H 627 N 581 Found C 7463 H 641 N 621
N-(Cinnamylidene)-2-hydroxy-5-chloroaniline (2d)Mp 91ndash93∘C IR 3344 3064 3013 2964 2911 2881 2839 1621 (C=N)1577 1501 1483 1445 1366 1240 1154 1082 979 837 804 742683 661 593 cmminus1 1H NMR (CDCl
3) 120575 841 (d J = 82Hz
1H N=CH) 754 (d J = 52 2H Ar) 743ndash700 (m 5H Aramp CH=CH) 729 (s 1H Ar) 722 (d J = 81Hz 1H Ar)690 (d J = 86Hz 1H Ar) 13C NMR (CDCl
3) 120575 15936
15095 (N=C) 14523 13647 13535 12999 12899 1283612811 12769 12494 11599 11586 Elemental Anal Calcd forC15H12ClNO C 6991 H 469 N 543 Found C 6880 H
472 N 536
N-(Cinnamylidene)-2-hydroxy-4-methylaniline (3d) Mp 97-98∘C IR 3350 3061 3012 2963 2912 2880 2840 1624(C=N) 1577 1541 1498 1447 1368 1257 1157 1092 975836 804 749 686 630 552 cmminus1 1H NMR (CDCl
3) 120575 857
(d J = 66Hz 1H N=CH) 766 (dd J = 60 19Hz 2H Ar)754ndash712 (m 5H Ar amp CH=CH) 730 (d J = 79Hz 1H Ar)693 (s 1H Ar) 680 (d J = 81Hz 1H Ar) 243 (s 3H Ar)13C NMR (CDCl
3) 120575 15685 15228 (N=C) 14326 13938
13571 13320 12953 12892 12873 12746 12075 1154811504 2146 Elemental Anal Calcd for C
16H15NO C 8098
H 637 N 526 Found C 7922 H 618 N 590
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors would like to thank the Middle East TechnicalUniversity analysis Center (Turkiye) for elemental analysesand Ozgur Ozdamar (Assistant Professor) and Hasan Saral(Assistant Professor) for the analysis NMR and IR of someimine compounds
References
[1] A M Asiri and S A Khan ldquoSynthesis and anti-bacterial activ-ities of some novel schiff bases derived from aminophenazonerdquoMolecules vol 15 no 10 pp 6850ndash6858 2010
[2] R W Layer ldquoThe chemistry of iminesrdquo Chemical Reviews vol63 pp 489ndash510 1963
[3] H-K Fun R Kia A M Vijesh and A M Isloor ldquo5-Diethy-lamino-2-[(E)-(4-methyl-3-nitrophenyl)iminomethyl]phenol aredeterminationrdquo Acta Crystallographica E Structure ReportsOnline vol 65 no 2 pp o349ndasho350 2009
[4] H Schiff ldquoSur quelques derives pheniques des aldehydesrdquoAnnali Di Chimica vol 131 p 118 1864
[5] K Taguchi and F H Westheimer ldquoCatalysis by molecularsieves in the preparation of ketimines and enaminesrdquo Journalof Organic Chemistry vol 36 no 11 pp 1570ndash1572 1971
[6] M E Kuehne ldquoThe application of enamines to a new synthesisof 120573-ketonitrilesrdquo Journal of the American Chemical Society vol81 no 20 pp 5400ndash5404 1959
[7] M A Vazquez M Landa L Reyes R Miranda J Tamarizand F Delgado ldquoInfrared irradiation effective promoter in theformation of N-benzylideneanilines in the absence of solventrdquoSynthetic Communications vol 34 no 15 pp 2705ndash2718 2004
[8] A K Chakraborti S Bhagat and S Rudrawar ldquoMagnesiumperchlorate as an efficient catalyst for the synthesis of iminesand phenylhydrazonesrdquo Tetrahedron Letters vol 45 no 41 pp7641ndash7644 2004
[9] H Naeimi H Sharghi F Salimi and K Rabiei ldquoFacile andefficient method for preparation of Schiff bases catalyzed byP2O5SiO2under free Solvent conditionsrdquo Heteroatom Chem-
istry vol 19 no 1 pp 43ndash47 2008[10] J H Billman and K M Tai ldquoReduction of Schiff bases
II benzhydrylamines and structurally related compoundsrdquoJournal of Organic Chemistry vol 23 no 4 pp 535ndash539 1958
[11] M Gopalakrishnan P Sureshkumar V Kanagarajan and JThanusu ldquoNew environmentally-friendly solvent-free synthesisof imines using calcium oxide under microwave irradiationrdquoResearch on Chemical Intermediates vol 33 no 6 pp 541ndash5482007
Organic Chemistry International 5
[12] J S Bennett K L Charles M R Miner et al ldquoEthyl lactateas a tunable solvent for the synthesis of aryl aldiminesrdquo GreenChemistry vol 11 no 2 pp 166ndash168 2009
[13] R S Varma R Dahiya and S Kumar ldquoClay catalyzed synthesisof imines and enamines under solvent-free conditions usingmicrowave irradiationrdquo Tetrahedron Letters vol 38 no 12 pp2039ndash2042 1997
[14] W A White and H Weingarten ldquoA versatile new enaminesynthesisrdquo Journal of Organic Chemistry vol 32 no 1 pp 213ndash214 1967
[15] F Texier-Boullet ldquoA simple convenient and mild synthesis ofimines on alumina surface without solventrdquo Synthesis vol 1985no 6-7 pp 679ndash681 1985
[16] L Ravishankar S A Patwe N Gosarani and A RoyldquoCerium(III)-catalyzed synthesis of schiff bases a greenapproachrdquo Synthetic Communications vol 40 no 21 pp 3177ndash3180 2010
[17] K P Guzen A S Guarezemini A T G Orfao R Cella CM PPereira and H A Stefani ldquoEco-friendly synthesis of imines byultrasound irradiationrdquo Tetrahedron Letters vol 48 no 10 pp1845ndash1848 2007
[18] R Annunziata M Benaglia M Cinquini and F CozzildquoPoly(ethylene glycol)-supported 4-alkylthio-substituted ani-line a useful starting material for the soluble polymer-sup-ported synthesis of imines and 1234-tetrahydroquinolinesrdquoEuropean Journal of Organic Chemistry no 7 pp 1184ndash11902002
[19] M Hosseini-Sarvari ldquoNano-tube TiO2as a new catalyst for
eco-friendly synthesis of imines in sunlightrdquo Chinese ChemicalLetters vol 22 no 5 pp 547ndash550 2011
[20] G Dutheuil S Couve-Bonnaire and X Pannecoucke ldquoDias-tereomeric fluoroolefins as peptide bond mimics preparedby asymmetric reductive amination of 120572-fluoroenonesrdquo Ange-wandte Chemie International Edition vol 46 no 8 pp 1290ndash1292 2007
[21] J F Collados E Toledano D Guijarro and M Yus ldquoMicro-wave-assisted solvent-free synthesis of enantiomerically pureN-(tert-Butylsulfinyl)iminesrdquo Journal of Organic Chemistryvol 77 Article ID 300919 pp 5744ndash5750 2012
[22] E Tauer and K H Grellmann ldquoPhotochemical and thermalreactions of aromatic Schiff basesrdquo Journal of Organic Chem-istry vol 46 no 21 pp 4252ndash4258 1981
[23] R J Argauer and C E White ldquoEffect of substituent groups onfluorescence ofmetal chelatesrdquoAnalytical Chemistry vol 36 no11 pp 2141ndash2148 1964
[24] J D Margerum and J A Sousa ldquoSpectroscopic studies ofsubstituted benzalanilinesrdquoApplied Spectroscopy vol 19 pp 91ndash97 1965
[25] J E Kuder H W Gibson and D Wychick ldquoElectrochemicalcharacterization of salicylaldehyde anilsrdquo Journal of OrganicChemistry vol 40 no 7 pp 875ndash879 1975
[26] F F Stephens and J D Bower ldquoThe preparation of benzimina-zoles and benzoxazoles from Schiff rsquos bases Part Irdquo Journal of theChemical Society pp 2971ndash2972 1949
[27] J Schmeyers F Toda J Boy and G Kaupp ldquoQuantitative solid-solid synthesis of azomethinesrdquo Journal of the Chemical SocietyPerkin Transactions 2 no 4 pp 989ndash993 1998
[28] W Xu S Zhang S Yang et al ldquoAsymmetric synthesis of 120572-aminophosphonates using the inexpensive chiral catalyst 111015840-binaphthol phosphaterdquoMolecules vol 15 no 8 pp 5782ndash57962010
[29] Y M S A Al-Kahraman H M F Madkour D Ali andM Yasinzai ldquoAntileishmanial antimicrobial and antifungalactivities of some new aryl azomethinesrdquoMolecules vol 15 no2 pp 660ndash671 2010
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Hindawi Publishing Corporationhttpwwwhindawicom
International Journal of
Analytical ChemistryVolume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Organic Chemistry International 5
[12] J S Bennett K L Charles M R Miner et al ldquoEthyl lactateas a tunable solvent for the synthesis of aryl aldiminesrdquo GreenChemistry vol 11 no 2 pp 166ndash168 2009
[13] R S Varma R Dahiya and S Kumar ldquoClay catalyzed synthesisof imines and enamines under solvent-free conditions usingmicrowave irradiationrdquo Tetrahedron Letters vol 38 no 12 pp2039ndash2042 1997
[14] W A White and H Weingarten ldquoA versatile new enaminesynthesisrdquo Journal of Organic Chemistry vol 32 no 1 pp 213ndash214 1967
[15] F Texier-Boullet ldquoA simple convenient and mild synthesis ofimines on alumina surface without solventrdquo Synthesis vol 1985no 6-7 pp 679ndash681 1985
[16] L Ravishankar S A Patwe N Gosarani and A RoyldquoCerium(III)-catalyzed synthesis of schiff bases a greenapproachrdquo Synthetic Communications vol 40 no 21 pp 3177ndash3180 2010
[17] K P Guzen A S Guarezemini A T G Orfao R Cella CM PPereira and H A Stefani ldquoEco-friendly synthesis of imines byultrasound irradiationrdquo Tetrahedron Letters vol 48 no 10 pp1845ndash1848 2007
[18] R Annunziata M Benaglia M Cinquini and F CozzildquoPoly(ethylene glycol)-supported 4-alkylthio-substituted ani-line a useful starting material for the soluble polymer-sup-ported synthesis of imines and 1234-tetrahydroquinolinesrdquoEuropean Journal of Organic Chemistry no 7 pp 1184ndash11902002
[19] M Hosseini-Sarvari ldquoNano-tube TiO2as a new catalyst for
eco-friendly synthesis of imines in sunlightrdquo Chinese ChemicalLetters vol 22 no 5 pp 547ndash550 2011
[20] G Dutheuil S Couve-Bonnaire and X Pannecoucke ldquoDias-tereomeric fluoroolefins as peptide bond mimics preparedby asymmetric reductive amination of 120572-fluoroenonesrdquo Ange-wandte Chemie International Edition vol 46 no 8 pp 1290ndash1292 2007
[21] J F Collados E Toledano D Guijarro and M Yus ldquoMicro-wave-assisted solvent-free synthesis of enantiomerically pureN-(tert-Butylsulfinyl)iminesrdquo Journal of Organic Chemistryvol 77 Article ID 300919 pp 5744ndash5750 2012
[22] E Tauer and K H Grellmann ldquoPhotochemical and thermalreactions of aromatic Schiff basesrdquo Journal of Organic Chem-istry vol 46 no 21 pp 4252ndash4258 1981
[23] R J Argauer and C E White ldquoEffect of substituent groups onfluorescence ofmetal chelatesrdquoAnalytical Chemistry vol 36 no11 pp 2141ndash2148 1964
[24] J D Margerum and J A Sousa ldquoSpectroscopic studies ofsubstituted benzalanilinesrdquoApplied Spectroscopy vol 19 pp 91ndash97 1965
[25] J E Kuder H W Gibson and D Wychick ldquoElectrochemicalcharacterization of salicylaldehyde anilsrdquo Journal of OrganicChemistry vol 40 no 7 pp 875ndash879 1975
[26] F F Stephens and J D Bower ldquoThe preparation of benzimina-zoles and benzoxazoles from Schiff rsquos bases Part Irdquo Journal of theChemical Society pp 2971ndash2972 1949
[27] J Schmeyers F Toda J Boy and G Kaupp ldquoQuantitative solid-solid synthesis of azomethinesrdquo Journal of the Chemical SocietyPerkin Transactions 2 no 4 pp 989ndash993 1998
[28] W Xu S Zhang S Yang et al ldquoAsymmetric synthesis of 120572-aminophosphonates using the inexpensive chiral catalyst 111015840-binaphthol phosphaterdquoMolecules vol 15 no 8 pp 5782ndash57962010
[29] Y M S A Al-Kahraman H M F Madkour D Ali andM Yasinzai ldquoAntileishmanial antimicrobial and antifungalactivities of some new aryl azomethinesrdquoMolecules vol 15 no2 pp 660ndash671 2010
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Hindawi Publishing Corporationhttpwwwhindawicom
International Journal of
Analytical ChemistryVolume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Hindawi Publishing Corporationhttpwwwhindawicom
International Journal of
Analytical ChemistryVolume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
