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以乳酸为单体,采用先缩聚后解聚的方法制备了L-丙交酯。首先通过正交实验较系统的研究了合成工艺,包括三种不同催化剂(锌粉、乙酸铜及辛酸亚锡)用量、脱水温度及裂解温度对产物收率的影响；进而考察了提纯方法对丙交酯最终产率及杂质(乳酸、水)含量的影响,并利用红外、热分析及核磁共振技术对产物结构进行了详细表征。结果表明,在辛酸亚锡催化下,脱水及裂解温度分别为130℃及190℃时,L-丙交酯单体的产率达到80%；通过多次重结晶可以得到较高纯度产物。
Using lactic acid as monomer, L-lactide was prepared by polycondensation followed by depolymerization. First of all, through orthogonal experiment, we systematically studied the synthesis process, including three different catalysts (zinc powder, copper acetate and stannous octoate), the dehydration temperature and the pyrolysis temperature on the yield of the product; then investigated the purification method of C Lactide final yield and impurities (lactic acid, water) content, and the use of infrared, thermal analysis and nuclear magnetic resonance technology for the product structure was characterized in detail. The results showed that under the catalysis of stannous octoate, the yield of L-lactide monomer reached 80% when the dehydration and pyrolysis temperatures were 130 ℃ and 190 ℃, respectively. The products with higher purity could be obtained by multiple recrystallization.