The method of preparation of 4-bromo-phthalic acid

The present invention discloses a method for preparing 4-bromo-phthalic acid, phthalic anhydride to the present invention, sodium hydroxide and sodium bromide as starting material, the phthalic anhydride uniformly mixed with sodium hydroxide, was added aqueous sodium hypochlorite solution is reacted under ultrasonic conditions, while controlling the pH of the reaction solution to give the desired product 4-bromo-phthalic acid. 4-bromo-phthalic acid purity is obtained by the method of the present invention is greater than 98.5%, a yield greater than 80%, in line with environmental protection requirements. The present invention as compared with the prior art, to avoid highly toxic, volatile high bromine used, the bromine utilization rate of 90% or more, and the recovered unreacted phthalic acid, to meet the requirements of the green chemical, the present invention carried out under ultrasonic conditions, selectivity, ease easy to control the reaction, yield, product quality and suitable for industrial production.