Symmetrical dicarboxylic acids with 4–14 carbon atoms gave selectively the corresponding monoesters in high yields in the transesterification catalysed by strongly acidic ion-exchange resins in ester–hydrocarbon mixtures. It was found that the rate of the esterification of the dicarboxylic acids is much higher than that of the monocarboxylic acids formed. This result can explain the high selectivity for the monoester formation and can also be explained by the existence of an aqueous layer on the surface of the resins. This method of selective esterification is quite simple and practical.
具有4至14个碳原子的对称二
羧酸在强酸性离子交换
树脂催化下的转酯化反应中,可以在酯-烃混合物中高选择性地获得相应的单酯,产率很高。研究发现,二
羧酸的酯化速率远高于形成的单
羧酸的速率。这一结果可以解释单酯形成的高选择性,也可以通过
树脂表面存在的
水层来解释。这种选择性酯化方法相当简单且实用。