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 |
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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 |
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ISSN: | 0352-5139 1820-7421 |
DOI: | 10.2298/JSC120802101W |