Salts of organic phosphates as catalysts for melt polycarbonate

A method for the preparation of bisphenol A polycarbonate said method comprising contacting at least one diaryl carbonate with bisphenol A in the presence of a transesterification catalyst and optionally a co-catalyst, at a temperature in a range between about 180° C. and about 310° C. and a pressure in a range between about 760 and about 1 torr to afford a product polycarbonate, said transesterification catalyst comprising at least one alkali metal or alkaline earth metal salt of an organic phosphate;

• said alkali metal or alkaline earth metal salt of an organic phosphate being selected from the group consisting of salts of adenosine 5′-monophosphate having structure III and salts of 2-deoxy-6-phosphogluconic acid having structure IV
• wherein A is independently at each occurrence an alkali metal ion or an alkaline earth metal ion;
• p is an integer having a value of 1 or 2, and X+ is a charge balancing species.

A method for the preparation of bisphenol A polycarbonate, said method comprising contacting bisphenol A with diphenyl carbonate at a temperature in a range between about 180° C. and about 310° C. and a pressure in a range between about 760 torr and about 1 torr in the presence of a transesterification catalyst comprising adenosine 5′-monophosphate disodium salt and tetrabutylphosphonium acetate co-catalyst, said diphenyl carbonate being present in an amount corresponding to between about 0.9 and about 1.2 moles diphenyl carbonate per mole of bisphenol A, said transesterification catalyst being present in an amount corresponding to between about 1×10−8 and about 2.5×10−4 moles catalyst per mole bisphenol A employed, said tetrabutylphosphonium acetate co-catalyst being present in an amount corresponding to between about 1×10−6 and about 1×10−2 moles tetrabutyl phosphonium acetate per mole bisphenol A employed.