Process for production of high-purity diaryl carbonate

In a process for the production of a high-purity diaryl carbonate in which a diaryl carbonate is produced by taking as a starting material a reaction mixture containing an alkyl aryl carbonate that has been obtained through a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound, continuously feeding the starting material into a reactive distillation column comprising a continuous multi-stage distillation column in which a homogeneous catalyst is present, carrying out a transesterification reaction and distillation simultaneously in said column, continuously withdrawing a low boiling point reaction mixture containing a produced dialkyl carbonate from an upper portion of the column in a gaseous form, and continuously withdrawing a high boiling point reaction mixture containing a diaryl carbonate from a lower portion of the column in a liquid form, wherein the improvement comprises:

• (a) said high boiling point reaction mixture is continuously introduced into a high boiling point material separating column A, and continuously subjected to separation by distillation into a column top component AT containing the diaryl carbonate and a column bottom component AB containing the catalyst and a high boiling point material;
• (b) said column top component AT is continuously introduced into a diaryl carbonate purifying column B having a side cut outlet, and continuously subjected to separation by distillation into a column top component BT, a side cut component BS and a column bottom component BB, the high-purity diaryl carbonate being continuously withdrawn as the side cut component BS;
• and
• (c) said column top component BT is continuously introduced into an intermediate boiling point material separating column C having a side cut outlet, and continuously subjected to separation by distillation into a column top component CT having said alkyl aryl carbonate as a main component thereof, a side cut component CS having as a main component thereof an intermediate boiling point material having a boiling point between that of said alkyl aryl carbonate and that of said diaryl carbonate, and a column bottom component CB having said diaryl carbonate as a main component thereof.