Patent ID: 7705107

Claim:
In a phase interface process for preparing aromatic polycarbonate comprising from 0.25 to 180 ppm of one or more carbamates of formula (1) wherein R 1 and R 2 are, independently of one another, H or C 1 to C 12 alkyl or together are a C 4 to C 12 alkylidene; and R 3 and R 4 are, independently of one another, H, C 1 to C 12 alkyl, or phenyl or together with the carbon atom to which they are bonded are cyclohexyl or trimethylcyclohexyl; comprising reacting at least one aromatic dihydroxy compound and phosgene in an alkaline medium, the improvement comprising (i) phosgenating at 0 to 40° C., (ii) maintaining the temperature of the reaction mixture at the time of addition of the catalyst at 10 to 40° C., and (iii) maintaining the molar ratio of aromatic dihydroxy compounds to phosgene at 1:1.05 to 1:1.20.