Synthesis of some novel bis-1,2,4-triazole and bis-1,3,4-thiadiazole derivatives from terephthaloyl and isophthaloyl chlorides

An efficient synthesis of novel bis-1,2,4-triazole and bis-1,3,4-thiadiazole derivatives starting from terephthaloyl and isophthaloyl chlorides is described. Terephthaloyl or isophthaloyl chloride was allowed to react with hydrazine hydrate in refluxing ethanol to give a corresponding bis-hydrazide derivative. Further reaction of these compounds with isothiocyanates gave bis-thiosemicarbazide derivatives, which then underwent cyclization to bis-1,3,4-thiadiazoles in the presence of sulfuric acid. The cyclization of these compounds in the presence of sodium hydroxide resulted in the formation of bis-1,2,4triazole-3-thioles. The structure of these compounds was characterized by IR, NMR, and elemental analysis.