ABSTRACT The synthesis of 1,2-O-isopropylidene acyl glycerol from 1,2-O-isopropylidene glycerol catalysed by Amberlite XAD-7 adsorbed lipase from Pseudomonas sp. AK was studied. The immobilized lipase preparation showed a maximum conversion degree of 75% of 1,2-isopropylidene lauroyl glycerol. The synthetic activity of the immobilized lipase was optimum at the temperature range of 30-50oC in n-hexane with an agitation rate of 150 rpm. The optimum ratio of 1,2-O-isopropylidene glycerol to lauric acid was 2:1 (mol/mol). Fatty acids of carbon numbers C12 – C18 which are readily miscible in apolar organic solvents show higher conversion degree. Apolar solvents with the Log P values of 3.0 and above, also resulted higher conversion degree. Salt hydrates with higher aw does not promote the catalytic activity of the immobilized lipase. The addition of CaCl2.2H2O or CaCl2.0/2H2O helped to control the water content in the system. On the other hand, a high aw saturated salt solution of 0.963 was needed to pre-equilibrate the lipase preparation for optimum conversion degree. Under the optimized reaction conditions, a maximum conversion degree of almost 90% was obtained after 24 h. The repeated use of the immobilized preparation for synthesis of 1,2-O-isopropylidene lauroyl esters was more than 60 repeated usage or 2 months maintaining the conversion degree in the range of 85 –90%.
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