Synthesis and characterization of some 2,5-disubstituted 1,3,4-thiadiazoles. 2-mercapto- and 2-alkylmercaptoderivatives

The new 2-mercapto-5-p(arylsulphonyl)phenyl-1,3,4-thiadiazoles I-e existing mainly in their thionic tautomeric form 1B - were synthesized by acid catalyzed cyclization of corresponding potassium acyldithiocarbazinates 4. Various S-alkylmercapto-1,3,4-thiadiazoles 1d-h, derived from 1a-c were obtained by two methods. The 2-mercapto-5-p(bromophenylsulphonyl)phenyl-1,3,4-thiadiazole (1c) showed a dichotomous behaviour in alkylation, affording S-alkyl (li-k) and N-alkyl (8a-c) derivatives. The new compounds were characterized by their IR-, UV- and H-1-NMR spectra.