A calorimetric and equilibrium investigation of the reaction {methyl ferulate(aq) + H2O(l) = methanol(aq) + ferulic acid(aq)}

Published

January 3, 2011

Author(s)

Robert N. Goldberg, Michael J. Selig, Stephen R. Decker, Brian E. Lang

Abstract

Microcalorimetry and high-performance liquid chromatography (HPLC) have been used to conduct a thermodynamic investigation of the reaction: {methyl ferulate(aq) + H2O(l) = methanol(aq) + ferulic acid(aq), as catlyzed by feruloyl esterase. Values of the apparent equilibrium constant K = 29.6  0.7 (temperature T = 298.15 K, citrate buffer at pH = 4.98, ionic strength I = 0.39 mol∙kg-1) and of the calorimetrically determined enthalpy of reaction ΔrH(cal) = (4.0  0.9) kJ∙mol 1 (T = 298.15 K and citrate buffer at pH = 4.81, I = 0.36 mol∙kg-1) were measured. A chemical equilibrium model, together with pKs and standard enthalpies of reaction ΔrH for the H+(aq) binding reactions of the reactants and products, was then used to calculate the values K = (1.89  0.06)∙10-4, rH = (7.3  1.7) kJ∙mol-1, ΔrG = (21.25  0.07) kJ∙mol-1, and ΔrS = (46.8  5.7) J∙K 1∙mol-1 for the chemical reference reaction {methyl ferulate(aq) + H2O(l) = methanol(aq) + ferulic acid-(aq) + H+(aq)}. These values of K and ΔrH are similar in magnitude to the corresponding values reported for the reaction {propyl gallate(aq) + H2O(l) = 3,4,5-trihydroxybenzoic acid-(aq) + 1 propanol(aq) + H+(aq)}. The results obtained in this study can be used in a chemical equilibrium model to calculate how K and other standard transformed properties such as the standard transformed enthalpy ΔrH, standard transformed Gibbs energy rG, and the change in binding of H+(aq), rN(H+), vary with the independent variables T, pH, and I.

Citation

Journal of Chemical Thermodynamics

Pub Type

Journals

Keywords

Biomass, Calorimetry, Enthalpy, Entropy, Ferulic acid, Feruloyl esterase, Methyl ferulate, Methanol, Standard Gibbs free energy

Citation

Goldberg, R. , Selig, M. , Decker, S. and Lang, B. (2011), A calorimetric and equilibrium investigation of the reaction {methyl ferulate(aq) + H2O(l) = methanol(aq) + ferulic acid(aq)}, Journal of Chemical Thermodynamics (Accessed April 24, 2024)