常压CO_2气流法制D,L-丙交酯

Preparation of Lactide from Lactic Acid at Normal Pressure \= by the CO\-2 Flow Process

在ＣＯ２气流中用Ｄ，Ｌ乳酸为原料，硫酸亚锡为催化剂，包括内外消旋体的粗丙交酯产率可达８２％，外消旋Ｄ，Ｌ丙交酯约占其中的１／２。作为对比，用Ｎ２气流时的粗丙交酯产率为８３．２％，二者产率相差无几。

Lactide was prepared in the CO\-2 flow starting from lactic acid and using stannous sulfate as catalyst.The yield of raw lactide including the racemic and meso isomers could reach 82% versus a yield of 83.2% in the N\-2 flow.The racemic D,L lactide accounted for about half of the yield.The results were very close to CO\-2 and N\-2 used,suggesting that CO\-2 can replace N\-2 in lactide producing process.\=