To a 1-L RBF is added 250 g of 1-chloro-2-(dichloromethyl)benzene and 500 g of conc. sulfuric acid, the mixture is stirred until the evolution of hydrogen chloride ceases. The emulsion is heated and stirred at 35°C for 12h, after which no further hydrogen chloride gas evolutes from the emulsion. The mixture is then poured into 3 liters of very cold water, allowed to stand for 30 minutes and the bottom layer is poured into a separatory funnel. The impure product is washed with 100ml of cold water and 100ml of cold saturated sodium carbonate solution. The liquid is then dried with some anhydrous magnesium sulfate and distilled under high vacuum.