Boric Acid Catalyzed Convenient Synthesis of Benzimidazoles in Aqueous Media

Table 1

Model reaction of o-phenylenediamine (1.0 mmol) with benzaldehyde (1.05 mmol) by using different amounts of catalyst boric acid in water at room temperature.

Entry	Amount of catalyst (%)	Reaction time (min)	Yield (%)^a
1	0	60	0
2	5	60	60
3	10	30	95
4	15	90	90
5	20	90	85

aIsolated yield.