乙醇酸和聚乙醇酸的制备与分离研究进展

乙醇酸作为一种重要的精细有机合成中间体，来源广泛。天然产物水解法，或化学法、生物法反应可得到乙醇酸粗品。现阶段我国乙醇酸的生产技术已经成熟，然而分离提纯乙醇酸的技术相对滞后。乙醇酸的分离提纯成为研究的重点和难点。本文着重总结了乙醇酸的5种分离提纯方法，主要有蒸馏和精馏法、结晶和重结晶法、甲醇酯化水解法、电渗析分离法、溶剂萃取法，其中甲醇酯化水解法和溶剂萃取法应用较多。指出了各种方法所得乙醇酸的纯度及其不足以及各种方法适用条件。此外，本文也综述了近几年合成聚乙醇酸的研究包括直接熔融聚合法、缩聚开环法、溶剂法、悬浮聚合法等，指出了各种方法的优缺点。最后，展望了乙醇酸和聚乙醇酸的应用前景，萃取法是得到高纯度乙醇酸的较好的方法，能为聚乙醇酸的合成提供优质原料，可以打破合成聚乙醇酸所用的乙交酯单体主要依赖于进口的局面。

Preparation and isolation of glycolic acid and polyglycolic acid

As an important intermediate for organic synthesis, glycolic acid can be obtained from many ways. Crude glycolic acid can be made by natural product hydrolysate, chemical method and biological method, respetively. At present, the separation and purification technology of glycolic acid in China exhibit many shortcomings although the production technology of glycolic acid is mature. In this paper, the separation and purification methods of glycolic acid were summarized, including distillation, crystallization and recrystallization, methanol esterification hydrolysis, electrodialysis separation, and solvent extraction. Among them, the methanol esterification hydrolysis method and the solvent extraction method are more popular. We pointed out the purities of glycolic acid could be achived by pre-mentioned method as well as their disadvantages and applicable conditions. One of the main uses of glycolic acid is to produce polyglycolic acid. The recent progress of synthesis of polyglycolic acid by different methods including direct melt polymerization, condensation polymerization, solvent method and suspension polymerization, was reviewed. Finally, we prospected the future developments of glycolic acid and polyglycolic acid. Solvent extraction is considered as a good way to get high-purity glycolic acid, which will provide excellent staring material for the synthesis of polyglycolic acid so as to reduce the importing glycolic acid.