Enzyme-catalyzed synthesis of alkyl-β-glucosides in a water-alcohol two-phase system

The enzymic synthesis of alkyl-beta -glucosides by water-immiscible alcohols was studied in stirred flasks as well as in a tubular enzymatic reactor. In the first case, direct alkylation of beta -D-glucose from hexanol using immobilized beta -glycosidase gave a higher conversion yield and final product concentration than that using the enzyme in its free state (yield 10 against 8% mol/mol, concentration 2 against 1.6 g/l). Direct glycosylation of beta -D-glucose from hexanol resulted in a higher reaction performance (yield 10%) than that from octanol (yield 5%). However, the two different incubation temperatures tested (37 degreesC and 50 degreesC), showed no significant differences concerning final product concentrations. The more interesting results were obtained by transglycosylation of methyl-1-beta -glucose from hexanol, with a conversion yield of 21% mol/mol (product amount 4 g/l). However, the transgalactosylation of lactose from hexanol, catalyzed by a fungal beta -galactosidase, showed only a feeble reactivity. The feasibility of enzymic alkylation was also tested in a tubular enzymatic reactor; hexyl-1-beta -glucoside was produced via direct glycosylation from hexanol catalyzed by free beta -glycosidase with a final concentration 1.3-2.3 g/l and a yield Varying between 11% and 20% mol/mol. (C) 2001 Elsevier Science Ltd. All rights reserved.