Brominating mono:vinyl aromatic cpd. oligomers - using starting oligomer still contg. olefinic double bonds to increase prod. heat-stability

摘要

Oligomers still contg. olefinic double bonds are used in the prepn. of brominated oligomers of monovinyl aromatic cpds. Prepn. process comprises dissolving the monovinyl aromatic cpd. oligomers in halogen-contg. solvents and reacting with Br2 at -25 to +130 deg.C, using Lewis acids as catalysts. The reaction soln. is then washed free from bromide, with water, and the brominated reaction prod. is sepd. from soln. The prods. can be worked to shaped articles and also used as flame-retardants for thermoplastics. Heat-stable ring-brominated prods. are obtd. contg. up to 71 wt.% Br and resisting heating for 10 min. at 240-340 deg.C without HBr generation and discolouration.