Oxidative Bromination Reaction of Phenol Catalyzed by Ammonium Tungstophosphat Catalyst Supported on Silica

Abstract

An efficient oxidative bromination reaction of phenol by KBr-H2O2 has been achieved in the presence of ammonium tungstophosphate catalyst supported on silica with different loadings,which were synthesized by sol-gel method.The effects of the reaction time and catalyst amount on the oxidative bromination reaction were also investigated.The results indicated that the Keggin structure of ammonium tungstophosphate could be retained after supported on silica,and these catalysts exhibited high bromination reaction catalytic activity with a yield of 96.4% and high selectivity of p-bromophenol with a p/o ratio of 3.2.After reaction,these catalysts can be recycled and still exhibited catalytic activity with a yield of 87.4% and a p/o ratio of 1.6 after four cycle reactions.