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

The enzymic synthesis of alkyl-b-glucosides by water-immiscible alcohols was studied in stirred ¯asks as well as in a tubular enzymatic reactor. In the ®rst case, direct alkylation of b-D-glucose from hexanol using immobilized b-glycosidase gave a higher conversion yield and ®nal 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 b-D-glucose from hexanol resulted in a higher reaction performance (yield 10%) than that from octanol (yield 5%). However, the two di€erent incubation temperatures tested (37°C and 50°C), showed no signi®cant di€erences concerning ®nal product concentrations. The more interesting results were obtained by transglycosylation of methyl-1-b-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 b-galactosidase, showed only a feeble reactivity. The feasibility of enzymic alkylation was also tested in a tubular enzymatic reactor; hexyl-1-b-glucoside was produced via direct glycosylation from hexanol catalyzed by free b-glycosidase with a ®nal concentration 1.3±2.3 g/l and a yield varying between 11% and 20% mol/mol