Effect of Acetaldehyde on Transesterification Catalyzed by Lipase in the Organic Phase
Lipase from pseudomonas fluorescenson was immobilized on a polyurea porous material activated by glutaraldehyde as carrier,and the resulting immobilized enzyme was used to catalyze the ester exchange reaction between(R,S)-1-phenylethanol and vinyl acetate.During the reaction process,the byproduct acetaldehyde inhibits the catalytic activity and stereoselectivity of lipase.This paper investigates the effects of acetaldehyde concentration,reaction solvent,and reaction temperature on the catalytic ability of enzymes in the presence of acetaldehyde.The results showed that the catalytic activity and selectivity of lipase were significantly inhibited in the presence of acetaldehyde.When the concentration of acetaldehyde is 0.025 mol/L,using n-hexane as the solvent,and the immobilized enzyme is used to catalyze the ester exchange reaction between(R,S)-1-phenylethanol and vinyl acetate at temperature 40 ℃.This moment,the catalytic activity and selectivity of the enzyme are least inhibited.After 5 reuse cycles,the system conversion decreased from 49.3％in the first time to 19.4％,and the enantioselectivity decreased to 26％,indicating that the presence of acetaldehyde accelerated the loss of enzyme activity.
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