Patent ID: 8034967

Claim:
A method of producing a purified ester-substituted phenol stream from a melt transesterification reaction byproduct stream, the method comprising the sequential steps of: (a) obtaining from a melt transesterification reaction a byproduct stream comprising a residual ester-substituted diaryl carbonate, an ester-substituted phenol, a residual melt transesterification catalyst, and a catalyst degradation product, wherein the melt transesterification catalyst comprises a tetraalkyl phosphonium hydroxide, a tetraalkyl ammonium hydroxide, or both, wherein at least one alkyl group of the tetraalkyl phosphonium hydroxide, the tetraalkyl ammonium hydroxide, or both, is a methyl group, and wherein the catalyst degradation product comprises a trialkyl phosphine, a trialkyl amine, or both, (b) treating the byproduct stream to separate ester-substituted phenol and catalyst degradation product from residual ester-substituted diaryl carbonate and residual melt transesterification catalyst, thereby creating a light recycle stream comprising ester-substituted phenol and catalyst degradation product and a heavy recycle stream comprising residual ester-substituted diaryl carbonate and residual melt transesterification catalyst, and (c) treating the light recycle stream to reduce catalyst degradation product concentration, thereby producing a purified ester-substituted phenol stream.