Thermolysis of some thiourea derivatives

Abstract

Thermolysis of N/benzoyl-N’,N’-diphenylthiourea (BDTU)( I ) at 250°C gives NH 3 , H 2 S, H 2 O, benzaldehyde, benzil, benzonitrile, diphenylamine, diphenylcyanamide, 2-phenylbenzimidazole, benzoyl isothiocyanate, carbazole and 2-phenylbenzthiazole, whereas, thermolysis of N-benzoyl-N'- o -tolylthiourea (BTTU) ( II ) under the same conditions afford NH 3 , H 2 S, H 2 O, benzaldehyde, benzil, benzonitrile, o -toluidine, o -tolyl isothiocyanate, o -tolylcyanamide, benzoyl isothiocyanate and N,N’-di- o -tolylthiourea. The main feature of these thermolyses is homolysis of the amide and thioamide bonds providing free radicals that undergo the common reactions involving H-abstraction, dimerization, coupling, fragmentation, rearrangement and cyclization. A suitable mechanism has been suggested to account for the observed products.