Study On Preparation Of Lactide Using Ionic Liquid Catalyst

Lactide is the indispensable mid-body to prepare polylactic acid which has been applied in many fields such as medicine, pharmacy and biomaterial due to its biodegradability, bioenvironmental compatibility and excellent mechanical properties. Current research focuses on the improvement of reaction technique and the selection and optimization of catalyst.This paper mainly focuses on the improvement of catalytic conditions. Lactide is prepared using three kinds of ionic liquids catalysts, whose catalytic efficiencies are investigated as well as reaction technique by contrasting traditional catalysts.(1) The synthesis process of lactide is considered as a intramolecular transesterification.(2) Lactide is prepared by traditional catalysts such as ZnO, Sn, SnCl2 and Sn(Oct)2. Results show that Sn(Oct)2 has the highest catalytic efficiency, and the catalytic efficiency of ZnO is lower than both Sn and SnCl2. The reaction technology is also investigated.(3) Lactide is prepared using three different kinds of ionic liquids catalysts, two neutral ones of which don't show obvious catalyse, while the other acidic one does lower catalyse than traditional catalysts. The influence factors on field of lactide are discussed. The optimium conditions for using acidic catalyst are that the dosage of catalyst is 5 wt%, oligomerization and depolymerization temperature is 140℃and ranges from 190～250℃separately.(4) The idea of applying liquid-liquid biphasic catalytic system in synthesis of lactide is considered. The complex catalytic is prepared primarily. At the same time, suggestions are mentioned.