Catalyst system for polycarbonate manufacture

A method for making polycarbonate, comprising,

• (A) affecting reaction under interfacial reaction conditions at a pH in the range of 9 to 12.5 between a phenolic chain-stopper and a bisphenol of the formula, ##STR2## where R5 is selected from the same or different C(1-4) alkyl group, and a substantially stoichiometric amount of phosgene in the presence of a phase transfer catalyst comprising a catalyst selected from the group consisting of:
• (R).sub.4 N+X
• R.sup.1 (R).sub.3 Q+X and
• (R.sup.2).sub.a (R.sup.3).sub.3-a N-(CH.sub.2).sub.n N-(R.sup.3).sub.3-a (R.sup.2).sub.a 2X
• where R is selected from the same or different C.sub.(4-10) alkyl group, R.sup.1 is a C.sub.(1-3) alkyl group, R.sup.2 is selected from the same or different C.sub.(1-2) alkyl group, R.sup.3 is selected from the same or different C.sub.(3-10) alkyl group, Q is a nitrogen or phosphorus atom, X is a halogen atom or an --OR.sup.4 group, R.sup.4 is a member selected from H, C.sub.(1-18) alkyl or C.sub.(6-18) aryl, and "a" is a whole number equal to 0 or 1, and additionally a methyl tertiary amine present in an amount ranging from about 0.001 to about 0.200 mole % based on the quantity of bisphenol, wherein the phase transfer catalyst is utilized in an amount which is effective for providing a polycarbonate having a molecular weight determined by gel permeation chromatography in the range of about 10.times.10.sup.3 to about 180.times.10.sup.3, and,
• (B) substantially eliminating chloroformate end groups in the resulting mixture of (A) prior to polycarbonate recovery.