Benzoylation of anisole over borate zirconia solid acid catalyst

Abstract

B2O3/ZrO2 solid catalyst containing 30 mol% boron oxide prepared by wet impregnation method and calcined at 500 °C showed efficient catalytic activity in liquid phase benzoylation of anisole with benzoyl chloride (BOC) in nitrobenzene solvent at 150 °C. B2O3/ZrO2 catalyst under study has shown comparable performance with conventional homogeneous AlCl3 catalyst as well as heterogeneous catalysts such as zeolite H-beta and sulphated zirconia with maximum conversion and selectivity to the corresponding 4-methoxy benzophenone (4-MBP). The effect of various experimental parameters such as temperature, nature of solvent, reaction time and the effect of various benzoylating agents has been discussed. The conversion of anisole to 4-MBP increases significantly with increasing reaction time and temperature. The maximum conversion of about 91% with yield of acylated product >96% and selectivity for 4-MBP >94% was observed after 22 h. 2-MBP was found to be <4%. The phenyl benzoate (3%) formed by the O-benzoylation of anisole was found to be a major side product. The catalyst was recycled three times without any appreciable decrease in the anisole conversion showing its stability.