丙三醇与CO_2合成丙三醇碳酸酯的间接路线及热力学探讨

Indirect route and thermodynamics for glycerol carbonate synthesis from glycerol and carbon dioxide

提出了以丙三醇制备3-氯-1,2-丙二醇(3-CPD)或缩水甘油,再与CO2反应合成丙三醇碳酸酯的间接路线。采用基团贡献法估算了部分物质的热力学函数及等压摩尔热容。利用这些估算结果和文献数据,计算了上述丙三醇衍生物与CO2合成丙三醇碳酸酯反应的焓变、吉布斯自由能变、平衡常数及常温下各反应自发进行所需的压强。结果表明,3-CPD与CO2合成过程常温下很难实现,在298.15 K^538.15 K范围,低温时其平衡常数甚至比丙三醇与CO2直接合成丙三醇碳酸酯反应的平衡常数低得多,高温时则有相同的数量级(10-9),而经缩水甘油的合成路线在热力学上具有独特优势。

Two indirect processes for synthesis of glycerol carbonate by reaction of CO2 with glycerol derivatives 3-chloro-1,2- propanediol （3-CPD） and glycidol, respectively, were proposed. Some unknown thermodynamic functions and constant pressure heat capacities were estimated by making use of the group contribution method, which and some data from the references quoted were used to calculate the changes of enthalpy, Gibbs free energy and equilibrium constants as well as the pressure needed for the spontaneous reactions at room temperature for synthesis of glycerol carbonate via the proposed processes. The results show that the synthetic reaction based on 3-CPD and CO2 is difficult to occur at ambient temperature, and compared to the reaction based on glycerol and CO2 in 298.15K to 538.15K, its equilibrium constant is even much lower at low temperature and has the same order of magnitude （10-9） at high temperature, however, the reaction based on glycidol and CO2 is thermodynamicaUy favorable.