中文摘要：

用1,4-去水山梨醇固定羧基,D,L-乳酸（2）经催化聚合制得低聚乳酸（5）;5经热裂解合成了丙交酯（3）。最佳反应条件为：2 960 mmol,n（OH）：n（2）=1：15,辛酸亚锡1.2%（以2质量计算）,在3.0 kPa下由90℃升温至160.0℃（2.0 h）;在0.4 kPa下由160℃升温至180.0℃（0.5 h）,于180.0℃反应5.0 h制得5;由180.0℃逐渐升温至230.0℃进行5的裂解反应,收集180.0℃～230.0℃馏分得1,收率96.1%,纯度97.5%。

英文摘要：

Lactide（1） with high purity was synthesized from D,L-lactic acid（2） using 1,4-dewatering orbital fixed carboxyl group by stannous octanoate-catalyzed polymerization to give low poly （lactic acid） （5） and then pyrolysis 5. The optimum reaction conditions were as follows ： 2 was 960 mmol, n （OH） ：n（2） was 1：15, stannous oetanoate was 1% mass of 2, under 3.0 kPa from 90 ℃ heating to 160.0 ℃（2.0 h）, under 0.5 kPa from 160 ℃ heating to 180.0 ℃ （0.5 h）, reacted at 180.0 ℃ for 5.0 h to give 5 ; cracking from 180.0 ℃ gradually heating to 230.0 ℃, to collect fraction between 180.0 ℃ -230.0 ℃ to obtain 1 in yield of 96.1% with purity of 97.5% o