Study on synthesis of 4-acetory benzoic acid with p-methylbenzenesulfonic acid as catalyst

4-acetory benzoic acid was prepared from p-hydroxy benzoic acid and acetic anhydride using p- methylbenzenesulfonic acid as catalyst.Many parameters including reaction temperature,reaction time,amount of catalyst were found to influence the yield of product.The optimum reaction condition are as follows∶n (p-hydroxy benzoic acid)∶n(acetic anhydride)∶n(p-methylbenzenesulfonic acid)=1∶2∶0.025,reaction time 30 min and reaction temperature 80~89℃,the yield was 91.63%