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RAM JANAM SINGH et al.
4-Methylphenyl isothiocyanate (1)
A mixture of 4-methylphenyl amine (0.01 mol), carbon disulfide (0.01 mol) and methanol
0
(50 mL) was cooled to 15 C. Ammonia (0.01 mol) was added drop wise to the reaction
mixture with continuous stirring. The mixture was allowed to stand overnight. Water was
added to the mixture (350 mL). An aqueous solution of lead nitrate (0.01 mol) was slowly
added to the solution. The mixture was then steam distilled to yield 4-methylphenyl
isothiocyanate (1). The IR (KBr) of the isolated 4-methylphenyl isothiocyanate indicates a
prominent characteristic band at 2071 cm-1 attributed to an N=C=S group (yield 70%).
1-(4-Methylphenyl-(isomeric pyridoyl) thiosemicarbazides (2a-c)
Pyridine carboxylic acid hydrazides (a-c) (0.01 mol) were reacted with 4-methylphenyl
isothiocyanate (0.01 mol) in the presence of absolute ethanol (50 mL); was refluxed for 1.5
hours. On cooling the mixture to room temperature, a white solid appeared. The crude solid
was filtered, washed with water and recrystallized from appropriate solvent to give
compounds (2a-c) yield (70-85%).
2,4-Dihydro-4-(4-methylphenyl)-5-(isomeric pyridyl) -3H-1,2,4-triazoles (3a-c)
General procedure
A mixture of compounds (2a-c) (0.01 mol) and 2 M sodium hydroxide solution (30 mL) was
refluxed for the period of 40 minutes. The resulting solution was cooled and poured on
crushed ice. The solid separated was filtered, washed with water and recrystallized from
ethanol-water to give compounds (3a-c) yield (75-85%).
0
3a: Yield 85%, m.p. 235 C, Anal.Calc. for C14H12N4S: C, 63.02; H, 4.61; N, 11.81%;
Found: C, 63.22; H, 4.41; N, 11.91%. IR (KBr): 1588 (C=N), 1510 (C-N), 730,715
(monosubstituted benzene) and 690 cm-1(C-S); PMR: δ2.35 (3H,s,CH3); 3.32(1H,bs,SH);
7.12(2H,m,Aromatic-H); 7.31(2H,m, Aromatic-H); 7.39 (1H,m,Pyridyl-H), 7.78(1H,m,
Pyridyl-H), 7.88(1H,m,Pyridyl-H) and 8.42 ppm (1H,m,Pyridyl-H); MS : m/z 265 (M+)
other peaks were observed at 263,207,163,107,95,81 and 53 .
0
3b: Yield 75%, m.p. 235 C, Anal.Calc. for C14H12N4S: C, 63.08; H, 4.58; N, 11.88%;
Found: C, 63.20; H, 4.39; N, 11.86%. IR (KBr): 1587 (C=N), 1511 (C-N), 732,712
(monosubstituted benzene) and 699 cm-1(C-S) ; PMR: δ2.35 (3H,s,CH3); 3.26 (1H,bs, SH);
7.21 (2H,d,Aromatic-H); 7.29 (2H,d, Aromatic-H); 7.38 (1H,m,Pyridyl-H), 7.66
(1H,m,Pyridyl-H), 8.45 (1H,dd,Pyridyl-H) and 8.55 ppm (1H,m,Pyridyl-H); MS : m/z 265
(M+) other peaks were observed at 263,207,163,107,95,81 and 53 .
3c: Yield 85%, m.p. 235 0C, Anal.Calc. for C14H12N4S: C, 63.05; H, 4.62; N, 11.83%; Found: C,
63.18; H, 4.37; N, 11.87%. IR (KBr): 1586 (C=N), 1515 (C-N), 735,710 (monosubstituted
benzene) and 688 cm-1(C-S); PMR: δ 2.28 (3H,s,CH3); 6.40 (1H,bs, SH); 7.10 (2H,d,Aromatic-H);
7.31(2H,d,Aromatic-H);7.65(2H,m,Pyridyl-H) and 8.82 ppm (2H,m,Pyridyl-H); MS:m/z 269
(M+) other peaks were observed at 266,210,209,162,105,92,79,59 and 51 .
Antibacterial activity
The antibacterial activity of three compounds was studied by employing filter paper disc
method9-12. Representative organisms selected for evaluation of antibacterial activity were S.
aureus, E.coli, B.subtilis and P.aeruginosa. The antibacterial activity of each compound was
evaluated at 100 µg mL-1and 10 µg mL-1 concentrations. The compounds were tested as a
solution or suspension in DMF. An important and useful drug ampicillin was also tested
under similar conditions, with view to compare the results.
Singh, Ram Janam
