A 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 aliphaticoligocarbonate diols bya) transesterifying dimethyl carbonate with aliphatic diols in the presence ofsoluble transesterification catalysts in a gas-liquid countercurrent apparatustoform oligocarbonates until the degree of conversion of the initial dimethylcarbonate is more than 80% andb) removing methanol and traces of dimethyl carbonate in an apparatus whichgenerates gas bubbles in the oligocarbonates until the degree of capping ofthe terminal OH groups with methoxycarbonyl groups is less than 5%.