Zhang Jicheng, Jiang Tao, Han Buxing, Zhu Anlian, Ma Xiumin, Zhou Yinxi, Bai Liang, Xiang Hongwei, Li Yongwang
Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
J Phys Chem B. 2007 May 17;111(19):5322-5. doi: 10.1021/jp070610m. Epub 2007 Apr 18.
The esterification of ethylene glycol with propionic acid was investigated in supercritical CO2 at 50.0 degrees C. The effect of pressure on equilibrium conversion and selectivity of ethylene glycol monopropionate (monoester) and ethylene glycol dipropinonate (diester) was studied systematically. It was shown that the equilibrium conversion and selectivity was nearly independent of pressure as pressure was lower than 9 MPa. At higher pressure, however, the yield and selectivity of the diester increased considerably, while those of the monoester decreased with increasing pressure. The main reason was that reactants and products distributed between the vapor phase and liquid phase at higher pressures. The solvent power of CO2 for the diester is stronger than that for the monoester. More diester molecules in the liquid phase were extracted into the vapor at higher pressures, which shifted equilibrium of the consecutive reversible reactions.
在50.0℃的超临界二氧化碳中研究了乙二醇与丙酸的酯化反应。系统地研究了压力对乙二醇单丙酸酯（单酯）和乙二醇二丙酸酯（二酯）平衡转化率和选择性的影响。结果表明，当压力低于9MPa时，平衡转化率和选择性几乎与压力无关。然而，在较高压力下，二酯的产率和选择性显著增加，而单酯的产率和选择性则随压力升高而降低。主要原因是在较高压力下反应物和产物分布在气相和液相之间。二氧化碳对二酯的溶剂化能力强于对单酯的溶剂化能力。在较高压力下，更多的二酯分子从液相萃取到气相中，这使连续可逆反应的平衡发生了移动。
