Process for the preparation of aliphatic oligocarbonate diols from dimethyl carbonate and aliphatic diols

摘要

The present invention relates to a process for the preparation of aliphatic oligocarbonate diols byPPa) transesterifying dimethyl carbonate with aliphatic diols in the presence of soluble transesterification catalysts in a gas-liquid countercurrent apparatus to form oligocarbonates until the degree of conversion of the initial dimethyl carbonate is more than 80% andPPb) removing methanol and traces of dimethyl carbonate in an apparatus which generates gas bubbles in the oligocarbonates until the degree of capping of the terminal OH groups with methoxycarbonyl groups is less than 5%.