Synthesis of 2-Phenylbenzimidazole Catalyzed by the Prepared Aminosulfamic Acid

2-phenylbenzimidazole was prepared by reaction of o-phenylenediamine and benzaldehyde in anhydrous ethanol,catalyzed by the prepared aminosulfamic acid.The product was characterized by UV-visible spectroscopy,Fourier transform infrared spectroscopy and(()~1HNMR). The effects of catalyst dosage,reactant ratio,reaction temperature,reaction time on the yield of product were investigated.The optimal condition is that the highest yield of 2-phenylbenzimidazole is 71.8% when the reaction is carricd out with ratio of amminosulfamic acid mass to o-phenylenediamine mole of 4.0 g/mol,the ratio of o-phenylenediamine to benzaldehyde of 2.5,at(85 ℃) for 3.0 h.