[Determination of 3,3'-dichlorodibenzoyl peroxide impurity in 3-chloroperbenzoic acid]

An ultraviolet spectrophotometric method has been developed for the determination of 3,3'-dichloro dibenzoyl peroxide impurity in 3-chloroperbenzoic acid, an important epoxidation agent in drug (especially steroid) syntheses. The method is based on the selective extraction of the main component by aqueous alkali from a chloroformic solution. The solution of the test substance (0.05-0.1 g in 50 ml chloroform) is extracted four times with 20 ml portions of 0.1 M aqueous sodium hydroxide and the absorbance of the resulting chloroformic solution in measured at 286 nm to calculate the content of 3,3'-dichloro dibenzoyl peroxide impurity. Beer's law is obeyed in the 0-10% impurity range. The A10/01 cm.value is 77.9 and the correlation coefficient of the regression equation was found to be 0.995. The relative standard deviation of the measurement in the case of 2% impurity was +/- 0.43%.