| 摘要 |
A continuous process is described for the production of a substantially acid free dialkyl maleate, for example diethyl maleate, from a feed stream containing a major amount of dialkyl maleate and a minor amount of the corresponding monoalkyl maleate. This comprises continuously distilling the feed stream in a primary distillation zone, to which is also supplied maleic anhydride so as to give (i) a bottom fraction containing monoalkyl maleate and dialkyl maleate in admixture, and (ii) a vaporous fraction that is substantially free from alkanol and comprises a mixture of diethyl maleate and maleic anhydride. The vaporous fraction (ii) is redistilled in a secondary distillation zone to yield (i) an overhead fraction containing maleic anhydride and (ii) a bottom fraction containing substantially acid free dialkyl maleate. <IMAGE> |
