Department of Chemical Engineering, Tsinghua University, Beijing 100084, PR China.
Bioresour Technol. 2010 Aug;101(15):5737-42. doi: 10.1016/j.biortech.2010.03.018. Epub 2010 Mar 21.
During Rhizopus oryzae-mediated methanolysis of triglycerides for biodiesel production, the amount of 1,2-DG and 2-MG as well as the ratio of 1,2-DG/1,3-DG and 2-MG/1-MG differed significantly in different reaction medium, which indicated that solvent might be a crucial factor that would influence the acyl migration rate, leading to varied biodiesel yield. In this paper, the influence of solvent and their properties on acyl migration kinetics of both 1,2-diglyceride and 2-monoglyceride were investigated systematically. It was found that decreasing solvent polarity would give increasing acyl migration rate constants in general. Solvent polarity influenced the acyl migration rate through the influence of the charge dispersion of the transition state. High polarity of the solvent was unfavorable to the transition state charge dispersion, which would increase its energy state, and thus decreased the acyl migration rate and then led to relatively lower methyl ester yield.
在根霉介导的甘油三酯甲醇解制备生物柴油过程中，不同反应介质中 1,2-DG 和 2-MG 的含量以及 1,2-DG/1,3-DG 和 2-MG/1-MG 的比值有显著差异，这表明溶剂可能是影响酰基迁移率的关键因素，从而导致生物柴油产率的变化。本文系统研究了溶剂及其性质对 1,2-二甘酯和 2-单甘酯酰基迁移动力学的影响。结果表明，一般来说，降低溶剂的极性会使酰基迁移速率常数增大。溶剂的极性通过对过渡态电荷分散的影响来影响酰基迁移速率。溶剂的高极性不利于过渡态电荷分散，从而增加其能量状态，降低酰基迁移速率，进而导致较低的甲酯产率。
