Lipase-catalyzed syntheses of oleic acid esters with various primary
alcohols have been performed
in a batch stirred tank reactor in an almost nonaqueous medium without
organic solvents. For all
syntheses 50 °C was found to be the optimal temperature. Initial
reaction rates were influenced by
the alcohol chain length. The study of the pressure stability of
the immobilized lipase from
Rhizomucor miehei (lipozyme IM) showed that the lipase
preparation is quite stable; it does not
lose its activity when it is exposed to carbon dioxide at 300 bar for
24 h. Esterification rates at
high pressure were determined, and it was found that they were higher
than at atmospheric pressure.
The highest rate and maximal conversion were near the critical
point of carbon dioxide.
Keywords: Esterification; batch reactor; lipase; Mucor miehei;
oleic acid esters; high pressure; carbon
dioxide; enzyme stability
The synthesis of oleyl oleate with immobilized 1.3-specific lipase from Mucor miehei is presented in this article. Oleyl alcohol was esterified with oleic acid in the presence of a Mucor miehei lipase (lipo-zyrnelM) to obtain oleyl oleate. The effets of various temperatures and various enzymehubstrate ratios have been investigated to determine optimal conditions for the esterification process. The highest conversion of oleic acid 86.9% was obtained at 50°C. The optimal addition of lipase to substrates was determined to be 0.1 g per gram of reaction mixture. The esterification can be modeled successfully as a reverse second-order reaction. Thermodynamic properties of the reaction system at 50°C were also determined. Activation energy was 14.65 kJ/ mol, entropy of activation -0.8 Jlmo1.K and free energy of activation was 98.568 kJlrnol.
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