A study of esterification of caffeic acid with methanol using p-toluenesulfonic acid as a catalyst

Caffeic acid (CA) can 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 the overall application in the lipid industry, so the synthesis of methyl caffeate (MC)using CA and methanol is a f...

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Veröffentlicht in:Journal of the Serbian Chemical Society 2013, Vol.78 (7), p.1023-1034
Hauptverfasser: Wang, Jun, Gu, Shuangshuang, Pang, Na, Wang, Fangqin, Wu, Fuan
Format: Artikel
Sprache:eng
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Zusammenfassung:Caffeic acid (CA) can 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 the overall application in the lipid industry, so the synthesis of methyl caffeate (MC)using CA and methanol is a feasible way to improve its lipophilicity. Here, the reaction conditions and kinetic parameters for the synthesis of MC using p-toluenesulfonic acid (PTSA) as a catalyst were firstly investigated, and the product was confirmed byliquid chromatography-mass spectrometry (LC-MS),Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and melting point analysis. The highest yield of MC catalyzed by PTSA reached 84.0% under the optimum conditions as follows: molar ratio of methanol to CA of 20:1, reaction temperature of 65?C, mass ratio of catalyst to substrate of 8 %, and 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 is k1 = exp (358.7 - 2111/T), and the activation energy is 17.5 kJ mol-1. These results indicated that the PTSA possesses high catalytic activity in the synthesis of MC, which is an efficient catalyst suitable for MC production in the chemical industry. nema
ISSN:0352-5139
1820-7421
DOI:10.2298/JSC120802101W