Green method of benzophenone synthesis

The oxidation of diphenylmethane with H₂O₂ under microwave irradiation was investigated using iron acetate as catalyst and glacial acetic acid as solvent. The results show that the application of iron acetate catalyst can not only promote diphenylmethane conversion, but also accelerate the reaction rate. Among all the reactions catalyzed by iron acetate, benzophenone could obtain the highest yield with the feed of 0.4 mmol of catalyst under the condition studied. It was found that the solvent glacial acetic acid plays an important role on the reaction that diphenylmethane was not react at all in the absence of glacial acetic acid. Benzophenone with the highest yield of 87.7% can be produced in 20 min under the condition of 365 W microwave power, 5 mL hydrogen peroxide w(H₂O₂)30%, 10 mL glacial acetic acid, 0.4 mmol iron acetate catalyst. This paper may provide a new green synthesis method of benzophenone in short reaction time without pollution, since a clean oxidation reagent, hydrogen peroxide, was used.