PROCESS FOR PRODUCING HIGH-PURITY DIPHENYL CARBONATE ON COMMERCIAL SCALE

摘要

This invention provides a production process of diphenyl carbonate which can produce high-purity diphenyl carbonate usable as a starting material of a high-quality and high-performance polycarbonate from a reaction mixture composed of a catalyst and a reaction by-product obtained, for example, from a transesterification using a dialkylcarbonate and phenol as a starting compound, on a commercial scale of 1 ton/hr stably for a long period of time. Although there are many proposals on a production process of a reaction mixture containing aromatic carbonates, for example, by reaction distillation, all of them are for a small, short-term and experimental scale. Accordingly, any specific method or apparatus, which can mass-produce, from the reaction mixture, a high-purity diphenyl carbonate usable as a starting compound for a high-quality, high-performance polycarbonate on a commercial scale have not hitherto been disclosed. In the production process of the present invention, a high-boiling substance separation column (A) comprising two specific continuous multistage distillation columns and a diphenyl carbonate purification column (B), are provided. When an apparatus comprising these columns connected to each other is used, a high-purity diphenyl carbonate important as a starting compound for a high-quality and high-performance polycarbonate can be produced stably from a diphenyl carbonate-containing reaction mixture on a commercial scale of at least 1 ton/hr for a longer period of time.