丙交酯合成过程的理论及实验研究

Theoretical and Experimental Studies on Synthesis of Lactide

采用密度泛函方法研究了丙交酯的合成过程,优化了合成过程中可能出现的化合物的几何构型,分析了各化合物的振动频率和偶极矩.在B3LYP/6-31G*和B3LYP/6-311+G*水平上进行了各化合物的能量计算,得到了所设计的各模型反应的焓变和吉布斯自由能变.结果表明,所选择的各模型反应为吸热反应且近似可逆,水的控制对丙交酯的形成很重要.根据量化计算结果与丙交酯合成实验中不同阶段反应体系红外谱图的变化,提出了丙交酯合成的可能机理.

Theoretical studies on synthetic process of lactide were carded out with density functional theory and the geometries of compounds maybe to appear in reactive system were optimized. The changes of enthalpy and Gibbs free energy were computed at B3LYP/6-31G^＊ and B3LYP/6-311＋G^＊ levels of theory, suggesting that the selected model reactions should be endothermal and approximately reversible. The resuits indicated that control of water in the reaction system was very important to the formation of lactide. By combination of the results of quantum computation with the infrared spectra obtained at various synthetic stage, the possible synthetic mechanism was proposed.