科研之友
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摘要
Caffeic acid (CA) could be considered as an important natural antioxidant. However, the low solubility and stability of CA in various solvent systems is a major limiting factor governing its overall application in the lipid industry. However, the synthesis of methyl caffeate (MC) using CA and methanol is a feasible way to improve its lipophilicity. Herein, the reaction conditions and kinetic parameters for the synthesis of MC using p-toluenesulfonic acid (PTSA) as a catalyst were investigated, and the product was confirmed by liquid chromatography-mass spectrometry (LC-MS), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy, and melting point analysis. The highest yield of MC catalyzed by PTSA attained 84.0 % under the optimum conditions as follows: molar ratio of methanol to CA of 20:1, reaction temperature of 65 degrees C, mass ratio of catalyst to substrate of 8 %, and a reaction time of 4 h. The esterification kinetics of CA and methanol is described by the pseudo-homogeneous second order reversible model. The relationship between temperature and the forward rate constant gives the activation energy of 17.5 kJ mol(-1). These results indicated that PTSA possesses high catalytic activity in the synthesis of MC, which is an efficient catalyst suitable for MC production in the chemical industry.
- 出版日期2013
- 单位中国农业科学院; 江苏科技大学
