In this study, a novel method for the direct synthesis of N-phenylbenzoimidazole was successfully developed. The title compound was synthesized via the reaction of benzimidazole with diphenylene io-donium trifluoromethanesulfonate without any metal catalysts and strong alkali. The title compound was characterized by ¹H NMR and ¹³C NMR spectra, and the optimal reaction conditions were determined. At the molar ratio of 1∶1.2 of benzimidazole to diphenylene iodonium trifluoromethanesulfonate, volume ratio of 1∶4 of ethanol to xylene, and at the reaction temperature of 120 ℃, the yield of the title compound N-phenylbenzoimidazole was up to 52.0% in 24 h, and the equal amount of iodine benzene was recycled. In addition, the proposed reaction mechanism was studied by HPLC technique.

Key words: 1-phenyl-1H-benzoimidazole, benzimidazole, diphenylene iodonium trifluoromethanesulfonate