bisphenol and 276 gm water the contents were purged with nitrogen to remove the air then 34 ml of 35 aqueous sodium hydroxide were added the nitrogen purge and stirring were continued for 5 minutes at this time 1 36 gms of 28 aqueous ammonium hydroxide were added and the contents stirred for another 5 minutes then 214 ml of methylene chloride were added with stirring for 5 minutes phosgenation was started with alternating additions of phosgene and additional 35 caustic as follows 14 gms phosgene 14 mls 35 naoh 10 gms phosgene 14 ml 35 naoh 6 gms phosgene 14 ml 35 naoh 5 gms phosgene 6 ml 35 naoh and finally 6 gms phosgene the phosgene gas feed rate was about 1 4 gms per minute the reaction temperature was 28 u00b0 35 u00b0 c the above reactants were digested with stirring for 20 minutes at 28 u00b0 c then a solution containing 3 6 gms ammonium chloride in 20 ml of water were added with digestion and stirring for another 20 minutes the reactants were allowed to separate into two phases the water phase was siphoned off the polymer solution was acidified with concentrated hcl then the solution was washed twice with water and transferred to a separatory funnel where it was allowed to stand for 2 hours the polymer solution was filtered through dry diatomaceous earth resulting in a clear colorless solution the polymer was cleaned up by precipitation of the methylene chloride polymer solution in hexane then filtered and vacuum dried at 100 u00b0 c this polymer was molded into tough clear test bars having the following properties ______________________________________loi astm d 2863 34weight averagemolecular wt 29 985by gel permation chromatographyir indicated carbamate groupsanalysis fornitrogen.