Preparation of brominated flame retardant (39568-99-5): 2,3,5,6-tetrabromo-p-xylene was synthesized by reaction of p-xylene with Br2 catalyzed by AlCl3, and the product was replaced by a-H.

1. Synthesis of tetrabromo-p-xylene: 1000kg bromine and 3kg anhydrous AlBr3 were added into the reactor in turn. Cooling with ice brine to 0-3 C, slowly adding 80 kg xylene under stirring. When the bulk or viscosity is too high in the reactor, the temperature can be controlled at 30-35 C by adding 450kg bromine dilution. The mass disappeared and then cooled to 10-15 (?) C. The remaining dimethylbenzene was added and reacted at 20 (?) C for 4-6 H. Excess bromine was evaporated. Put the reaction liquid into the centrifuge to filter and dry. Recrystallization with methanol, melting point 253 - 254 C.

2. Synthesis of hexabromo-p-xylene: 80 kg of carbon tetrachloride was added to the reactor and 42 kg of tetrabromo-p-xylene was added under stirring. Under the protection of N2, carbon tetrachloride solution of bromine (32 kg bromine dissolved in 50 L carbon tetrachloride) was slowly added and heated for 15 hours. Then it is cooled to about 3 degrees Celsius. A, a', 2, 3, 5, 6-hexabromo-p-xylene was obtained by centrifugal filtration and drying.

Product Specification: Indicator Name Indicator Appearance White Crystallization Melting Point /~272.5~273.5 Bromine Content /%>81