Thermolysis of trimethylamine–benzimide and related compounds: identification of by-products and their probable mechanism of formation

Abstract

The thermolysis of trimethylamine–benzimide gives, in addition to trimethylamine and triphenyl isocyanurate (from trimerisation of the first-formed phenyl isocyanate) already reported, small amounts of benzanilide, NN′-diphenylurea, 2-phenylbenzimidazole, and carbon dioxide. Inter alia, 2-phenylbenzimidazole is also obtained from thermolysis of N-methylpiperidine–benzimide, NN′-di-m-methoxyphenylurea from thermolysis of trimethylamine–m-methoxybenzimide, and 2-phenyl-1H-naphth[1,2-d]imidazole from thermal decomposition of trimethylamine–benzimide in α-naphthyl isocyanate. These products are considered to arise from a subsidiary reaction involving the amine–imide and the isocyanate.