Enzymatic synthesis and analytical monitoring of terpene ester by 1H NMR spectroscopy

Terpene esters of fatty acids have potential applications in food, cosmetic, and pharmaceutical industries. The present study focuses on the synthesis of terpene esters of long chain fatty acids catalyzed by Candida antarctica lipase B. Different parameters like temperature, solvent, and enzyme concentration for the esterification of terpene alcohols (geraniol and citronellol) with oleic acid were studied. Maximum conversion (98 %) was found for both terpene esters at 60 degrees C in 2,2,4-trimethylpentane as well as in dry hexane and around 95-97 % in other tested solvents. The reaction was also carried out using stearic and linoleic acid in hexane to study the effects of unsaturation in the substrate in which stearic acid showed the maximum conversion. The reaction was monitored by H-1 nuclear magnetic resonance spectroscopy. Using the peak integration values of methylene protons of terpene and terpene ester of delta = 3.6 and 4.0 for citronellol and delta = 4.2 and 4.6 for geraniol, respectively, percentage conversions of each of the esters were calculated. (C) 2011 Institute of Chemistry, Slovak Academy of Sciences