Purification of crude deca:bromo-di:phenyl ether - by grinding to fine particle size and heat treating, gives stable prod. useful as flame retardant agent for polymers

摘要

Crude solid decabromodiphenylether (I) contg. occluded bromine and HBr as impurities, is purified by (a) grinding the crude (I) to a particle size predominantly less than ca. 20 microns dia. and substantially entirely less than 100 microns dia., and (b) heating the comminuted prod. at 150-300 deg.C for a time sufficient to effect substantial removal of the impurities. The crude (I) is prepd., e.g. by reacting diphenyl oxide in an excess of bromine without other reaction solvents in the presence of a bromination catalyst, the reactants being substantially free from impurities contg. aliphatic and alicyclic hydrocarbon gps., the diphenyl oxide contg. no more than 5000 ppm dibenzofuran and 2-phenylphenol and the bromine being substantially free of chloroform and CCl4. Pref. the bromine is distilled before reaction with the diphenyl ether, and is esp. treated with Al or AlCl3 prior to distn. The purified (I) has improved thermal stability and is useful as a flame-retardant agent in polymeric compsns. such as HIPS used, e.g. in television cabinets and other consumer appliances. The purified (I) has less tendency to discolouration and improved thermal stability under the processing and moulding condictions encountered whilst processing the polymer compsns. contg. it.