Synthesis and IR spectra of 2-phenylbenzimidazole and its amino derivatives

2-Phenylbenzimidazole and its mono and diamino derivatives were synthesized in yields up to 85% by cyclodehydration of o-aminobenzanilides in hydrochloric or sulfuric acid. The IR spectra of the compounds obtained were studied, the principal bands of the stretching and deformation vibrations of the NH and NH₂ groups were assigned, and the presence of associates with a hydrogen bond was established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 115–116, January, 1973.