Liquid phase bromination of phenol over titania pillared zirconium phosphate and titanium phosphate

The liquid phase bromination of phenol was carried out using titania pillared zirconium phosphate (ZrP) and titanium phosphate (TiP) as catalysts, KBr as brominating agent and hydrogen peroxide as an oxidant by varying different reaction parameters. With increase in the catalyst concentration and the reaction time, there is an increase in the formation of brominated phenol. But as far as selectivity is concerned, with time it did not follow a definite trend in case of 2-BP and di-BP. But the selectivity of 4-BP increases with time. The reaction proceeds through the formation of Br+ (bromonium ion) which attacks the phenol ring forming different brominated products. (C) 2005 Elsevier B.V. All rights reserved.