Lipase-catalyzed synthesis of geranyl acetate in n-hexane with membrane-mediated water removal

The esterification of geraniol with acetic acid in n‐hexane was investigated. A commercial lipase preparation from Candida antarctica was used as catalyst. The equilibrium conversion (no water removal) was found to be 94% for the reaction of 0.1 M alcohol and 0.1 M acid in n‐hexane at 30°C. This was shown by both hydrolysis and esterification reactions. The activation energy of reaction over the temperature range 10° to 50°C was found to be 16 kJ/mol. The standard heat of reaction was −28 kJ/mol. Membrane pervaporation using a cellulose acetate/ceramic composite membrane was then employed for selective removal of water from the reaction mixture. The membrane was highly effective at removing water while retaining all reaction components. Negligible transport of the solvent n‐hexane was observed. Water removal by pervaporation increased the reaction rate by approximately 150% and increased steady‐state conversion to 100%. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 676–681, 2001.