The general procedure for the synthesis of 1-bromo-2,5-dichlorobenzene and 1,4-dibromo-2,5-dichlorobenzene from 1,4-dichlorobenzene was as follows: 147.0 g (1.00 mol) of 1,4-dichlorobenzene was accurately weighed in a reactor, 515 g of carbon tetrachloride was added as a solvent, and dissolved by stirring. Subsequently, 7.35 g of anhydrous aluminum chloride was added as a catalyst and after stirring for 15 minutes, the reaction system was warmed up to 35°C. At this temperature, 105.6 g (0.66 mol) of bromine was started to be added dropwise at a constant drop rate and the dropwise process lasted for 9 hours to complete. Upon completion of the reaction, the reaction was terminated by adding 200.0 g of 5% mass fraction sodium bisulfite solution to the reaction mixture until the mixture became colorless. After standing and layering, the organic phase was separated and the resulting carbon tetrachloride layer was concentrated. Ultimately, 73.0 g (0.50 mol) of unreacted 1,4-dichlorobenzene, 111.5 g (0.48 mol) of 1-bromo-2,5-dichlorobenzene and 7.1 g (0.02 mol) of 1,4-dibromo-2,5-dichlorobenzene were obtained by distillation.
