Process for the preparation of bisphenol A of polycarbonate purity

摘要

The present invention relates to a method to obtain polycarbonate-grade Bisphenol A. The Bisphenol A product is obtained by condensation of phenol with acetone in the presence of an acid ion-exchange resin catalyst in three steps in a single reactor and then Bisphenol A is separated from the resulting post-reaction mixture by way of a one-step or two-step suspension crystallization, adduct decomposition, and distilling off of phenol, and acetone is added to the obtained phenol and other phenolic fractions to obtain a concentration in the range 3-10% and contacted at a temperature in the range 50-870C with an acid ion exchange resin after part of its sulfonic groups have been neutralized with 2,2-dimethylthiazolidine or cysteamine, and is sent to the first or second step of suspension crystallization. In one of the embodiments of the invention, the resulting Bisphenol A is subjected to falling-film fractional crystallization.