Thermolysis of some thiourea derivatives

Abstract

Thermolysis of N/benzoyl-N’,N’-diphenylthiourea (BDTU)(I) at 250°C gives NH3, H2S, H2O, 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 NH3, H2S, H2O, 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.