Process for the production of polycarbonate using an ester substituted diaryl carbonate

A method of preparing polycarbonate comprising the steps of:

• (a) forming a melt reaction mixture comprising an ester substituted diaryl carbonate mixture, a dihydroxy compound, and a melt transesterification catalyst, wherein:
• the ester substituted diaryl carbonate mixture may contain acid-substituted phenol and is:
• (i) tested for the presence of said acid-substituted phenol prior to forming the melt reaction mixture, and
• (ii) if said acid-substituted phenol is present, treated to reduce the level of said acid-substituted phenol to an amount of less than 100 ppm,
• (b) allowing the melt reaction mixture to react to build molecular weight, thereby preparing a polycarbonate.

A method of preparing an ester substituted diaryl carbonate mixture suitable for use in a melt polymerization reaction, the method comprising the steps of:

• (a) providing an initial ester substituted diaryl carbonate mixture comprising an ester substituted diaryl carbonate, wherein said initial ester substituted diaryl carbonate mixture contains acid-substituted phenol, if at all, in an amount less than 100 ppm,
• (b) adjusting, if necessary the pH of the initial ester substituted diaryl carbonate mixture to a pH of less than 11, and
• (c) controlling contact of the ester substituted diaryl carbonate mixture with water, transesterification catalyst, and/or heat,
• whereby the amount of acid-substituted phenol present in the ester substituted diaryl carbonate mixture is maintained in an amount less than 100 ppm, thereby preparing an ester substituted diaryl carbonate mixture suitable for use in a melt polymerization reaction.