[Synthesis of dicarboxylic esters by lipase]

The syntheses of dicarboxylic esters by immobilized lipase from Candida sp.--1619 were investigated. The reaction system was composed of 1 mmol dicarboxylic acid, 2 mmol alcohol, 3 mL hexane and 15 mg celite-adsorbed immobilized lipase(300 u), in a closed 100 mL Erlenmeyer flask, shaken at 40 degrees C for 5 h. Sebacic acid was the best substrate among nine dicarboxylic acids selected. Among the 18 saturated fatty n-alcohols, the alcohols with carbon chain length rangin from C4-C18 had good reactivity. The primary alcohols had much better reactivities than corresponding secondary alcohols and multihydroxy-alcohols. Tertiary alcohols showed no reactivity. Hydrocarbons, benzene, toluene, xylene and tetrachloride were favorite reactants among 15 organic solvents selected, in none-solvent stationary system, (5 mmol sebacic acid, 10 mmol dodecanol, 150 mg immobilized lipase(3000 u)) reacted without plug for 3.5 h, the optimum temperature was 60 degrees C. The conversion degree was over 92% when reaction carried out at 50-90 degrees C for 17 h. The suitable reaction pH ranged from 6-8. The reactant was developed on GF254 plate (hexane:ethyl ether:acetic acid = 30:20:1 (V:V:V). There were three spots with different Rf value at 0.96, 0.55 and 0 corresponding to product, oleyl alcohol and sebacic acids, respectively.