ADDITIVE TAILORING IN BIPHASIC SYSTEMS FOR AN ENZYMATIC CONDENSATION REACTION

摘要

The enzymatically catalysed reaction between dodecanol and glucose to form dodecylglucoside was studied. This reaction serves as a model for two phase reaction systems in which the reagents have very little mutual solubility. Typically, both the rate and the yield in such reactions are slow. Five solvents (additives) were tested for their effect on reaction equilibrium, butanone, butanedione, formamide, methylformamide and dimethylformamide. These additives were introduced in relatively small amounts, insufficient to combine the two phases into one. Butanone addition reduced the yield of the reaction, while the others increased it in the sequence: butanedione methylformamide > dimethylformamide formamide. Addition of butanedione to the reaction system, in an amount equal to about 15% of the total, resulted in 500% increase in the yield of dodecylglucoside formation. Analysing the effects of the various additives indicate that the most efficient ones are: a) lypophilic solvents of relatively high polarity, which increase the solubility of the product in the organic phase and b) hydrophilic solvents of relatively low polarity, which improve the solubility of dodecanol in the aqueous reaction medium.