Conversion Of TFAAE To (R)-TFHBE By Microorganism

Biocatalysis and chiral synthesize is payed much more attention to nowadays because of its mild reaction environment, high selectivity, less co-reaction, high yield, high optical purity, less pollution to environment, less produce cost. In this article, it was researched that the asymmetric reduction of TFAAE to optically active (R)-TFHBE was catalyzed by microorganisms in aqueous phase. The results are as follows.Saccharoinyces uvarum SW-58 producing TFAAE reductase with high enantioselectivity was isolated from the microorganisms preserved in our laboratory. It has high molar conversion rate in the reaction of TFAAE asymmetry reduction.After studied, the optimum fermentation conditions are as follow: 60 g/L sodium acetate as carbon source, 30 g/L corn steep liquor as nitrogen, 6 g/L KH2PO4, 1 g/L MgSO4·7H2O, fermentation temperature 30°C, initial pH 6.0, fermentation time 36 h. The highest enzyme activity of the carbonyl reductase of ethyl 4,4,4-trifluoroacetoacetate reaches 319.2 U/L, and the concentration of (R)-ethyl 4,4,4-trifluoro-3-hydroxybutanoate reaches 4.6 g/L, higher than the initial condition's 3.5 g/L, and the optical purity of (R)-ethyl 4,4,4-trifluoro-3-hydroxybutanoate reaches 85.0 %e.e., which is much higher than 60.8 %e.e. of the initial condition.The optimum reduction conditions refer to these factors: 40 g/L yeast concentration, reduction system pH 5.0, reduction temperature 30°C, 5% glucose as co-substrate, 30 g/L substrate concentration, reduction time 6 h. It was found that the yeast was restrained by the product when the product concentration was above 10 g/L before the reduction happened. Also, the methods controlling e.e. value was researched. The results are as follows: e.e. value enhanced a little when the inhibitor ally bromide was put into the system, but the molar conversion rate descended; there was no effect of heating yeast on e.e. value; after twice crystallization, e.e. value reached 97.3%.The resin NKA-II was put into the reduction system in order to relieve the substrate and product restraint. Firstly, absorption time and the resin quantity was determined. Then the effects of substrate concentration on the reduction and the resin absorption capacity of the glucose were studied too. After optimum, the molar conversion rate enhanced 66.9%, the highest TFHBE concentration reached 26.2 g/L.The method for separating TFHBE was also described. Under the optimum reaction conditions mentioned above, solvent extraction, evaporation and vacuum distillation were...