Synthesis and spectroscopic properties of new azo dyes derived from 3-ethylthio-5-cyanomethyl-4-phenyl-1,2,4-triazole.

New 1,2,4-triazole colorants were obtained, in high yields, by coupling 3-ethylthio-5-cyanomethyl-4-phenyl-1,2,4-triazole (1) with diazotized aniline derivatives 2, 4 and 6. The azo dyes prepared in this work may exist in three tautomeric forms. We found that the tautomerism is influenced mainly by the nature of substituent at the para position of the aniline coupling component. This tautomerisation was observed in the NMR spectra of the dyes. The dyes were characterized by IR, ¹H-NMR, ¹³C-NMR and MS spectroscopic techniques.