2-(4-aminophenyl)benzimidazole were synthesized by the reaction of o-phenylenediamine with 4-Aminobenzoic acid in the presence of polyphosphoric acid under microwave irradiation.The effect of the microwave irradiation time

a reaction material mole of ratio

the catalyst quantity to responded the production rate were examined

and the products were analyzed by measuring its melting point

IR and 1HNMR.Through the analysis of experiment data

the optimum conditions are as follows: microwave power of 80 W

microwave irradiation time of 10 min

the mole ratio of o-phenylenediamine to 4-Aminobenzoic acid of 1∶1.3

catalyst quantity of 6 mL

the yield is 89.5%

and the melting point is 227.4 ℃ to 229.8 ℃.