【摘要】 为降低D,L-丙交酯的生产成本,将微波技术引入到其生产工艺中.以D,L-乳酸为原料单体,减压下采用连续微波辐射法制备D,L-丙交酯.对制备过程中的脱自由水条件、催化剂种类及用量、聚合过程微波功率与时间、裂解过程微波功率进行优化.对提纯的D,L-丙交酯做熔点分析、元素分析、红外光谱分析及核磁共振分析.结果表明,催化剂选用SnCl2与助催化剂A的复合体系;100 mL乳酸经绝对压力20 kPa、170℃脱自由水10 min,微波功率80 W聚合30 min,微波功率200 W裂解得粗产物.粗产物经无水乙醇重结晶3次可获得产率达36%的纯D,L-丙交酯.相比于传统加热法,微波辐射法稍提高了D,L-丙交酯的产率,同时制备时间缩短了1/2~4/5,因而有助于其成本的降低.更多还原

【Abstract】 Aiming at reducing the cost of D,L-lactide, the microwave technology was introduced into its preparation process in this paper.D,L-lactide was prepared using D,L-lactic acid as the material under successive microwave irradiation and reduced pressure.The conditions of free water removal,species and dosages of catalysts,microwave power and irradiation time in polymerization procedure and microwave power in depolymerization procedure were optimized.D,L-Lactide was characterized by melting point,elemental analysis,IR and 1H-NMR.The results show that the system of SnCl2 and Cat.A is suitable for the catalysis;crude product is prepared with 100 mL lactic acid by 10 min of free water removal under 20 kPa and 170 ℃,30 min of polymerization under microwave power 80 W,and depolymerization under microwave power 200 W.D,L-lactide is obtained with the yield of 36%by recrystalizing the crude product by ethanol for 3 times.The yield is promoted a bit and the preparation time is reduced by 1/2～4/5 compared with the conventional heating,which helps to reduce the cost.更多还原