Kinetic resolution of (R,S)-2-methyl-hexanoic acid alkanoic ester via Carica papaya lipase-catalyzed hydrolysis in water-saturated organic solvents

• Main Authors: Mao-Yu Chu, 朱懋育
• Other Authors: Chun-Sheng Chang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/98125343737695208899

碩士 === 南台科技大學 === 生物科技系 === 98 === Branched chain fatty acids (BCFAs) are fatty acids substituted with alkyl groups. Many of them are chiral and therefore occur in two enantiomeric forms. Chiral BCFAs have been recognized as important flavour components. 2-Methylalkanoic acids and their derivates of high enantiomeric purities have also served as valuable synthetic intermediates. The purpose of this research is aimed to study the effect of organic solvents, reaction temperature, and different alkyl chain length of the chiral center of (R,S)-2-methylhexanoic acid esters by using partilly purified Carica papaya lipase ( pCPL ). The hydrolytic resolution of (R,S)-butyl-2-methylhexanoic ester via pCPL in different water-saturated solvents at 35℃ is employed as the model system for studying the effects of solvents on the lipase activity and enantioselectivity, where water-saturated isooctane are beneficial for giving better lipase activity and enantioselectivity. A comparison of pCPL enantioselectivity of alkyl chain straight for (R,S)-2-methylhexanoic acid esters of different indicates that (R,S)-butyl-2-methylhexanoic ester gives the best lipase activity. The thermodynamic analysis indicates that the enantiomer discrimination is driven by the difference of activation enthalpy ( ΔΔH ) and that of activation entropy ( ΔΔS ), yet the former is dominated for most of the reacting systems and has a good linear compensation relationship with the latter. Similar of the E value for different alkyl chain lengths of the chiral center of (R,S)-2-methylhexanoic acid esters were mainly attentted by both enthalpic and entropic changes.