Patent ID: 7498399
Filing Date: 2009-03-03
Classification: B01J,C07C,C08G

Abstract:
1. In a method of making an ester-substituted diaryl carbonate by reacting phosgene with a recycle stream of ester-substituted phenol from a reaction process using a tetraalkyl phosphonium hydroxide, a tetraalkyl ammonium hydroxide, or both, as a catalyst, the improvement comprising: treating the recycle stream to reduce a catalyst degradation product concentration, if catalyst degradation product is present, prior to the reaction with phosgene, wherein the catalyst degradation product comprises a trialkyl phosphine, a trialkyl amine, or both, and wherein at least one alkyl group of the tetraalkyl phosphonium hydroxide or the tetraalkyl ammonium hydroxide is a methyl group.