Thermodynamics of the Lipase Catalyzed Transesterifation of (-)-Menthol and Dodecyl Dodecanoate in Organic Solvents

Published

March 20, 2000

Author(s)

Yadu D. Tewari

Abstract

The thermodynamics of the lipase-catalyzed transesterification reaction (-)-menthol(sin) + dodecyl dodecanoate(sin) = (-)-menthyl dodecanoate(sin) + 1-dodecanol(sin)have been studied. Equilibrium measurements were performed as a function of temperature with n-heptane, toluene, and 2,2,4-trimethylpentane as solvents. The results of the equilibrium measurements were used to calculate the standard molar Gibbs energy δ_fG _m, enthalpy δ_fH _m, and entropy δ_fS _m changes for the above reaction in these three solvents at the temperature T = 298.15 K. The values of the δ_fG _m and δ_fH _m in these solvents ranged, respectively, from 1.5 to 2.6 kJ mol^-1 and from 0.2 to 4.0kJ mol^-1. The (n-hexane + water) partition coefficients of the reactants and products were also determined at T - 298.15 K. A thermochemical cycle calculation was then used to calculate a value for the equilibrium constant K = 2.4 0.7) x 10^-3 and δ_fG _m = (14.9 0.7) kJ mol^-1 for the above reaction in water. However, the average value of the equilibrium constant for reaction (1) in the organic solvents is remarkably constant, namely = 0.372 (estimated standard deviation of the mean = 0.014). Thus, the thermodynamics of this reaction in water are substantially different than in the organic solvents studied herein.

Citation

Journal of Molecular Catalysis B-Enzymatic

Volume

9

Issue

1-3

Pub Type

Journals

Keywords

(-)-menthol, (-)menthyl dodecanoate, 1-dodecanol, dodecyl dodecanoate, equilibrium constants, lipase, organic solvents, partition coefficients, solubility

Citation

Tewari, Y. (2000), Thermodynamics of the Lipase Catalyzed Transesterifation of (-)-Menthol and Dodecyl Dodecanoate in Organic Solvents, Journal of Molecular Catalysis B-Enzymatic (Accessed May 4, 2024)