2 4 benzoyl 3 hydroxyphenoxy ethyl chloroformate in 30 ml of methylene chloride were added dropwise over 10 minutes after the reaction mixture was stirred an additional 5 minutes 8 3 ml ca 119 0 mmoles of liquid phosgene and 12 0 g 150 0 mmoles of 50 sodium hydroxide were added dropwise over 20 minutes the reaction mixture was cooled as was necessary in order to hold the temperature between 20 u00b0 and 25 u00b0 c once the addition of phosgene was completed 0 5 ml ca 4 9 mmoles of triethylamine was added the reaction mixture was stirred another 30 minutes at the end of this time the ph of the aqueous phase was 12 14 according to ph paper the phases were separated the methylene chloride phase was washed once with dilute aqueous hcl solution and once with water it was then added dropwise to 1 0 l of vigorously stirred methanol the resultant precipitate was filtered washed with fresh methanol and dried in a vacuum oven to yield 30 1 g theory 38 3 g of white powder analysis by high performance lc indicated the presence of less than 0 1 weight residual 2 hydroxy 4 2 hydroxyethoxy benzophenone in the product analysis by ultraviolet uv spectroscopy showed that the product contained about 4 weight of attached 2 4 benzoyl 3 hydroxyphenoxy ethoxycarbonyloxy uv absorbing groups based on the method of preparation and analyses the product formed in this reaction i 17 was a bis 2 4 benzoyl 3 hydroxyphenoxy ethoxycarbonyloxy endcapped tetrabromobisphenol a polycarbonate pc oligomer endcapping a bisphenol a polycarbonate pc with 2 4 benzoyl 3 hydroxyphenoxy ethyl chloroformate compound i 18 a 2 0 l.