Patent ID: 7718820

Claim:
A process for the preparation of an alkanediol and a dialkyl carbonate comprising: (a) reacting an alkylene carbonate and an alkanol feedstock in a first reaction zone under transesterification conditions to obtain a product mixture of dialkyl carbonate, unconverted alkanol, the alkanediol, unconverted alkylene carbonate and dimers of the alkanediol; (b) separating dialkyl carbonate and alkanol from the product mixture to obtain a bottom product stream containing alkanediol, unconverted alkylene carbonate and dimers of the alkanediol; (c) recovering the dialkyl carbonate; and (d) separating alkanediol from the bottom product stream to leave a recycle stream comprising unconverted alkylene carbonate and dimers of the alkanediol, which process further comprises (e) passing at least part of the recycle stream to a second reaction zone in which the dimers of the alkanediol are converted to higher-boiling oligomers of alkanediol, yielding an oligomers-containing effluent; (f) separating the higher-boiling oligomers from the oligomers-containing effluent yielding an alkylene carbonate-containing remaining stream; and (g) recycling the alkylene carbonate-containing remaining stream to the first reaction zone.