Lipase-catalyzed enantiomeric synthesis of citronellyl butyrate
1995
Wang, Y. (Helsinki Univ. of Technology, Espoo (Finland)) | Linko, Y.Y.
Lipases from Candida rugosa, Pseudomonas fluorescens and Rhizopus japonicus were employed in direct esterification of the different optical isomers of citronellol with butyric acid both with and without additional organic solvent. In systems with C. rugosa lipase and without addition of organic solvent, the highest ester yields in 18 h reaction were 98% for R(+)-citronellol at 12% water content and 67% for S(-)-citronellol at 18% water content, respectively. In comparison, a yield of only 65% was obtained with at otherwise similar conditions but with an optimum water content of about 18%. No ester synthesis took place in "dry" n-hexane of about 1.2 ppm of water. When water content was increased to 0.1% in n-hexane system, rapid esterification occurred also in n-hexane with all three substrates, but three was little enantioselectivity. Both P. fluorescens and R. japonicus lipases exhibited somewhat higher initial rates for citronellyl butyrate synthesis, with greater than 80% yield with R(+)-citronellol in 4 h
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