丙交酯作为合成聚乳酸（PLA）的中间体，其化学及光学纯度决定着 PLA 的品质。本文阐述了以乳酸为原料，两步法制备丙交酯过程中温度、压力、反应时间、催化剂种类及用量等工艺条件对最终产品收率及纯度的影响。针对高温裂解所引起的问题，提出采用新技术、新型反应设备及开发高效均相催化剂等方法使反应在较温和的条件下进行。同时，对溶剂重结晶法、萃取法、精馏法及熔融结晶法在丙交酯提纯上的应用及特点作了介绍，指出综合各种精制技术的耦合法精制工艺路线将具有较好的发展前景，而将熔融结晶技术与其他方法相耦合则是一种更为绿色可行的技术路线。最后，指出不断研发新的绿色提纯工艺技术，仍是丙交酯合成技术的关键所在。%Lactide is an intermediate in the synthesis of polylatic acid(PLA),and its chemical and optical purity have a significant effect on the quality of PLA. In this paper,the process of synthesizing lactide by two-step approach was outlined and the influence of temperature,pressure,reaction time, catalyst and its quantity on the yield and purity of lactide was investigated. Through adopting new technology,new type reaction equipment and developing more efficient and homogeneous catalyst,the problem caused by pyrolysis could be resolved. Various methods for purifying lactide,such as solution crystallization,extraction,distillation and melt crystallization methods,were also discussed. Coupling various refining technologies will have a bright prospect,while integrating melt crystallization with other method is one of the most promising and feasible technical route. Finally,developing novel and environmentally friendly purification technology will still be the key to synthesizing lactide.
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