减压气流法合成D,L-丙交酯

Synthesis of D,L-lactide by Decompression and Flow Method

以质量分数85%的D,L-乳酸为原料,采用先常压除水,然后加入辛酸亚锡催化剂,减压除水,通氮气将生成的丙交酯蒸出的工艺路线,减少了原料损失,提高了产率。使用循环水真空泵代替油泵,低真空度条件下成功得到了丙交酯,降低了设备成本。然后对比了乙酸乙酯和乙醇作为溶剂对粗产品的提纯,发现无水乙醇的结晶效果好于乙酸乙酯。最后用核磁、红外等对纯化后的丙交酯进行了表征。

Using D,L-lactic acid of mass fraction 85% as raw material, the water was removed under normal pressure. Then adding tin octoate as catalyst, the water was eliminated under decompression. Produced lactide was brought out by the flow of nitrogen. The above process route can decrease the loss of raw material and increase the yield of lactide. The lactide was successfully obtained under low vacuum degree produced by circulating water vacuum pump instead of oil pump, so device cost was reduced. Comparing ethyl acetate with ethyl alcohol as solvents in raw product purification, the result shows that absolute alcohol is better than ethyl acetate in crystallization effect. At last, the lactide purified was characterized by 1H-NMR, FT-IR, etc.