Bromination of low molecular weight aromatic polymer compositions

A process which comprises brominating an aromatic polymer composition of the formula:

• wherein for each molecule of formula (I), n is an average number in the range of about 2.5 to about 8 with the proviso that 1,3-diphenylpropane, a compound of formula (I) in which n is 0, optionally is present in this aromatic polymer composition in an amount of not more than about 1 GPC area %, and with the further proviso that this aromatic polymer composition optionally further contains toluene in an amount of not more than about 0.1 GPC area %, to form a brominated aromatic polymer composition having a bromine content as determined by XRF in the range of about 70 to about 76 wt %, which process comprises brominating said aromatic polymer composition with liquid bromine in the presence of an aluminum halide bromination catalyst and in the absence of light, at a bromination temperature in the range of about −10° C. to about +5° C., and in which the molar ratio of total amount of bromine fed:total amount of catalyst fed is in the range of 200:1 to about 500:1, which process is further characterized in that:
• a) the total amount of said catalyst is charged into a reactor which is at a temperature in the range of about −25° C. to about 0° C., said reactor containing an inert atmosphere and a portion of bromination solvent such that the initial weight percentage of said catalyst expressed as aluminum is in the range of about 0.02 wt % to about 0.04 wt %;
• b) within about 2 hours after completing the charge of the catalyst, separate concurrent feeds of (i) bromine, and (ii) a solution of said aromatic polymer composition in the bromination solvent are initiated, said feeds being conducted such that said solution and the liquid bromine are fed to maintain a substantially constant molar ratio of aromatic polymer composition to bromine entering the reactor;
• and
• c) wherein on completion of the feeds and an optional ride time of no greater than about 60 minutes, the weight percentage of aluminum relative to the total of the mass of the bromination solvent and the brominated aromatic polymer composition in the reactor is greater than about 0.015 wt %.