The thermodynamics of the lipase-catalyzed esterification of glycerol with n-octanoic acid have been investigated with acetonitrile, benzene, and toluene as solvents and in the neat reaction mixture (no organic solvent added). This esterification reaction leads to five products: 1-monooctanoyl glycerol, 1,2-diotanoyl glycerol, 1,3-diotanoyl glycerol and 1,2,3-trioctanoyl glycerol. This, in turn leads to a total of 12 reactions. Values of the equilibrium constants for these reactions have been measured (HPLC, GC, and LC/MS) at 37 C in the above mentioned media. The equilibrium constants range from 0.9 to 20.7, 0.20 to 8.0, 0.23 to 10.0, and 0.57 to 2.2 in acetonitrile, benzene, toluene, and neat media, respectively. Relative standard molar Gibbs free energies of formation δfGo/m of 1-monooctanoyl glycerol, 2-monooctanoyl glycerol, 1,2-dioctanoyl glycerol, 1,3-dioctanoyl glycerol and 1,2,3-trioctanoyl glycerol in the organic solvents and in the neat reaction mixture been calculated and used to compactly summarize the thermodynamics of these reactions. The results show an approximate correlation with the permittivities of the solvents.
Citation: Journal of Molecular Catalysis B-Enzymatic
Issue: No. 4-6
Pub Type: Journals
diotanoyl glycerol, equilibrium constant, equilibrium constants, esterification, glycerol, lipase, monooctanoyl glycerol, n-octanoic acid, triooctanoyl glycerol