The enantioselective hydrolysis of 3-hydroxy-5-phenyl-4-pentenoicacidethylester in supercritical carbon dioxide using lipases

A new experimental high-pressure-unit was constructed for the enantioselective enzymatic hydrolysis of 3-hydroxy-5-phenyl-4-pentenoicacidethylester (a precursor for biological interesting substances) in a biphasic buffer/SCCO2-system. One objective is to take advantage of the solubility differences of the substrate and the produced acid. Thus the different solubilities of the substrates and the products in the different phases were studied regarding to an overall process integration. One ester enantiomer is preferably hydrolyzed, the other remains in the supercritical phase. And the produced acid enantiomer is concentrated in the buffer phase. The decrease in pressure is followed by an extraction process of the remaining substrate-enantiomer, in consequence it will be possible to combine an enzymatic reaction with a separation step. The catalysis was optimized in regard to enantioselectivity, enantiomeric excess, conversion and reaction time. A high enantioselectivity is achieved for the aromatic substrate using the lipase of Pseudomonas cepacia. The results show that this unconventional reaction system offers tremendous advantages for enzyme process development.