Patent ID: 7345133

Claim:
In the process of producing branched polycarbonate by the phase boundary process the improvement comprising using at least one compound conforming to formula (1) in which R 1 , R 2 , R 3 and R 4 mutually independently denote C 1 -C 10 alkyl, R 5 , R 6 and R 7 mutually independently denote hydrogen or C 1 -C 10 alkyl, or R 1 and R 2 , and R 3 and R 4 , with the carbon atom to which they are attached, form a C 5 -C 10 cycloalkyl group, wherein the cycloalkyl group may be substituted said compound characterized in that it is the crude, unpurified product of re-crystallization or melt crystallization of bisphenol A or its derivative.