A Simple and Efficient Procedure for Synthesis of Biologically ... - ISCA

Research Journal of Chemical Sciences Vol. 1 (1) April (2011)
Res.J.Chem.Sci.
Synthesis of benzoic acid hydrazide (2): A mixture
methyl benzoate (0.01 mole) and hydrazine hydrate
(0.5 g, 0.01 mole) was heated for 9 hrs. and poured
into ice. The product was isolated and crystallized
from ethanol.
Synthesis of potassium-benzoic acid hydrazide
dithiocarbamate (3): A mixture of benzoic acid
hydrazide (0.01 mole), KOH (0.84 g, 0.015 mole)
and 1.5 ml CS 2 in absolute alcohol was stirred for 21
hrs. and product was isolated from diethyl ether.
Synthesis of 4-amino-5-phenyl-4H-1,2,4-triazole-
3-thiol (4): Potassium salt (0.01 mole) was taken in
hydrazine hydrate and heated up to the evolution of
H 2 S gas cussed nearly 5 hrs. in oil bath. The reaction
mixture was poured into crushed ice and treated with
glacial Acetic acid .The product was filtered and
purified by KOH treatment and crystallized from
ethanol.
Synthesis of 3-(phenyl)-6-(4-N-acetylamino
phenyl) [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole (5):
A mixture of n-acetyl-p-amino benzoic acid (0.01
mole) and 4-amino-5-phenyl-4H-1,2,4-triazole-3-
thiol (0.01 mole) in POCl 3 (25 ml) was refluxed for
10 hrs. The reaction mixture was poured into crushed
ice and thus solid separated out was filtered, washed
with water and crystallized from ethanol.
Synthesis of 3-(phenyl)-6-(4-amino phenyl)
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole (ATT) (6):
3-(phenyl)-6-(4-N-acetylamino phenyl) [1,2,4]
triazolo[3,4-b][1,3,4]thiadiazole was hydrolysed by
refluxing with 75 ml of ethanol containing 15 ml of
concentrated HCl for 4-5 hrs. it was then poured into
ice-cold water and finally made just alkaline with
liquid ammonia. The resultant product 3-(phenyl)-6-
(4-amino phenyl) [1,2,4] triazolo [3,4-b] [1,3,4]
thiadiazole (ATT) is filtered off and washed with
water and air dried. It was then recrystallised from
ethanol.
Synthesis of Arylidine-[3,6-(diphenyl)-
[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole] (7a-h): A
mixture of equimolar amount of 3-(phenyl)-6-(4-
amino phenyl) [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole
19
(0.01 mole) and various aromatic aldehydes
(0.01mole) in 50 ml acetic acid and refluxed for about
10-12 hrs. on oil bath. The reaction mixture was
cooled and it was poured in to ice water and extracted
with ethyl acetate and water and finally dried over
anhydrous sodium sulfate. The solvent was evaporated
to give the solid product. It was crystallized from ethyl
acetate hexane using decolorizing charcoal to give
various anils
Synthesis of 3-[(3,6-diphenyl)-[1,2,4]triazolo[3,4-
b][1,3,4]thiadiazole]-2-aryl-thiazolidine-4-ones (8ah):
A mixture of Schiff bases (7a-h) (0.01 mole ) in
THF (30 ml) and mercapto acetic acid (thioglycolic
acid) (0.01 mole) with a pinch of anhydrous ZnCl 2
was refluxed for 12 hours. The solvent was then
removed to get a residue, which was dissolved in
benzene and passed through column of silica gel using
benzene : chloroform (8:2;v/v) mixture as eluent. The
eluate was concentrated and the product crystallized
from alcohol to give 4-thiazolidinones(8a-h).
Spectral Analysis of Synthesized compounds (8ah)
(1) 3-[(3,6-diphenyl)-[1,2,4]triazolo[3,4-b][1,3,4]-
thiadiazole]-2-phenyl-thiazolidin-4-one (8a): I.R.
(KBr, cm-1): 3030, 1500 (aromatic C-H), 1600, 1680
(C=O of thiazolidinone). PMR (δ ppm): 6.12-7.8 (m,
aromatic), 3.1 (2H of CH 2 for thiazolidinone), 5.35
(H of C 2 H for thiazolidinone). 13 CMR (δ ppm): 113-
130 (benzene),136-145 (triazolo-thiadiazole), 169
(C=O), 36 (CH 2 ), 46 (CH).
(2) 3-[(3,6-diphenyl)-[1,2,4]triazolo[3,4-b][1,3,4]-
thiadiazole]-2-(4-methoxyphenyl)-thiazolidin-4-
one (8b): I.R. (KBr, cm-1): 3030, 1500 (aromatic C-
H), 1600, 1690 (pyridine ring, C=O of
thiazolidinone), 1200 (Ar-O-CH 3 ). PMR (δ ppm):
6.12-7.8 (m, aromatic), 3.2 (2H of CH 2 for
thiazolidinone), 5.35 (H of C 2 H for thiazolidinone),
3.35 (3H of CH 3 of thiazolidinone). 13 CMR (δ ppm):
113-131 (benzene),135-145 (triazolo-thiadiazole),
169 (C=O), 36 (CH 2 ), 46 (CH), 56 (CH 3 ).
(3) 3-[(3,6-diphenyl)-[1,2,4]triazolo[3,4-
b][1,3,4]-thiadiazole]-2-(4-hydroxyphenyl)-
thiazolidin-4-one (8c): I.R. (KBr, cm-1): 3030,