Synthesis of Tautomeric Forms of 5-(2-Hydroxyphenyl)-4-substituted-3H-1,2,4-triazole-3-thione

Abstract

In this study, salicylic acid hydrazide 1 was converted into 1,4-substituted thiosemicarbazides (2a-f). The 1,4-substituted thiosemicarbazides were then converted into 5-(2-hydroxy phenyl)-4-substituted-3H-1,2,4-triazole-3-thione (3a-f). In addition, the aminomethylation compounds of 5-(2-hydroxy phenyl)-4-substituted-3H-1,2,4-triazole-3-thione (4a-f) were synthesized by the Mannich reaction of 3a-f and then {[5-(2-hydroxy phenyl)-4-methyl-4H-1,2,4-triazol-3-yl]thio}acetic acid (5a-f) were prepared by 3a-f. The structures of all the synthesized compounds were confirmed by elemental analyses, X-ray, FT-IR, H-1 NMR and C-13 NMR spectra. Their thiol-thione tautomeric equilibrium is described.