Deep eutectic solvents Clause Samples

Deep eutectic solvents. There are a few applications of DES in the extraction of natural products. This is probably due to their high viscosity and most are in nearly solid state at room temperature. However, DES made of glycerol and choline have relative low viscosity and are good solvents for enzyme reaction. Hydrolases show good catalytic activity in DES including choline chloride-acetamide, choline chloride-glycerol, choline chloride-urea. In those DES, lyophilized Candida antarctica lipase B shows higher activity than that in the conventional solvent, toluene. Particularly, in choline chloride-glycerol, the conversion is much higher than in toluene (22% vs 5%) with lyophilized Burkholderia cepacia lipase. Furthermore, the enzyme activity of lyophilized Candida antarctica lipase B did not decrease in choline chloride-urea at 60 oC over 90 min (▇▇▇▇▇ et al., 2008). The high activity and stability of hydrolases in DES show the promise of DES as solvents in biotransformation. The enzymatic transesterification of Miglyol oil 812 catalyzed by Novozym 435, a commercial immobilized Candida antarctica lipase B, showed high reaction rates in choline acetate:glycerol (1:1.5) at 50 oC. The high conversion rate of up to 97% ensures the further exploration of DES as potential solvents in enzyme reactions (▇▇▇▇ et al., 2011).