Patent ID: 7122613

Claim:
A method for the manufacture of a polycarbonate comprising: reacting a carbonate precursor with a dihydroxy compound in the presence of an aqueous base in an inert organic solvent optionally containing a molecular weight regulator, to form an oligomeric polycarbonate, wherein the reaction between the dihydroxy compound and the carbonate precursor upon formation of the oligomeric polycarbonate is about 80 to 99% completed; removing the inert organic solvent and the aqueous base to isolate the oligomeric polycarbonate; and transesterifying the isolated oligomeric polycarbonate to form a polymeric polycarbonate at a temperature and pressure effective to remove trace amounts of residual solvent; wherein the catalyst is sodium hydroxide, lithium hydride, sodium dihydrogen phosphite, caesium dihydrogen phosphate tetramethylphosphonium acetate, tetraethylphosphonium acetate, tetrapropylphosphonium acetate, tetrabutylphosphonium acetate, tetrapentylphosphonium acetate, tetrahexylphosphonium acetate, tetraheptylphosphonium acetate, tetraoctylphosphonium acetate, tetradecylphosphonium acetate, tetradodecylphosphonium acetate, tetratolylphosphonium acetate, tetraphenylphosphonium acetate, tetramethylphosphonium benzoate, tetraethylphosphonium benzoate, tetrapropylphosphonium benzoate, tetraphenylphosphonium benzoate, tetramethylphosphonium formate, tetraethylphosphonium formate, tetrapropylphosphonium formate, tetraphenylphosphonium formate, tetramethylphosphonium propionate, tetraethylphosphonium propionate, tetrapropylphosphonium propionate, tetramethylphosphonium butyrate, tetraethylphosphonium butyrate, tetrapropylphosphonium; or a combinations comprising at least one of the foregoing and is added in an amount of about 1×10 −9 to about 1×10 −4 moles/mole of oligomeric polycarbonate.