Brief Study On Chiral Alcohol's Synthesizing By Microbiological Transformation

Chirality, which is named as asymmetry also, is the most basic attribute of the natural world. Chiral substance plays an important part in our lives and is applied in many areas such as drugs, pesticides and materials. The chiral molecule of aromatic alcohol, has significant function in drugs'synthesis that it's the key intermediates. Microbiological catalysis is applied in research of chiral synthesis to recover the disadvantages of traditional chemistry methods, with advantages of short reaction cycle, soft conditions, low cost and simple operation. Baker's yeast is usually used in chiral research.Research about the synthesis of aromatic alcohol which is get from reduction of aromatic ketone, focus on the substrate acetophenone and haloacetophenone, and other kinds of substrate did not referred nearly.Consequently, our experiment planned to reduce the substrate of acetophenone and 2-amino-1-acetophenone with baker's yeast to get phenylethanol and 2-amino-1- phenylethanol, who are the key intermediates in the synthesis of drugs.For the former substrate of acetophenone, we first preserved and cultivated the baker's yeast under laboratory condition, then we also do fermentation to baker's yeast and collected large amount of baker's yeast which was put into the fridge of 4℃to execute the late reduction. After this, we mixed the baker's yeast, acetophenone and aided substrate glucosamine in the system of PBS with certain proportion, and put the mixture in the jerking table with 120r/min, 30℃and 50h. After 50 hours'reaction, we extracted the mixture three times with acetate. After centrifugation, we collected organic phase and determinated every index. Through the gas chromatograph determination, we proved that chiral phenylethanol was produced during the catalysis with yield of 35%, and most of the product was S-phenylethanol with e. e. of 95%. Then, we got the reaction course curve by determinating the concentration of substrate and product in some point of the reaction, and we also knew that the reaction lasted in the former 30 hours. After all of these, we did single element experiment for the five element of reaction: temperature, pH, concentration of acetophenone, amount of baker's yeast and concentration of glucosamine, and got the best condition with temperature of 30℃, pH of 7.0, acetophenone concentration of 22mmol/L, baker's yeast amount of 0.24g/ml, glucosamine concentration of 0.2g/ ml and time of 30h.For the new substrate of 2-amino-1-acetophenone, we did the similar experiment to reduction of acetpohenone. The result of gas chromatograph showed that we got the chiral 2-amino-1-phenylethanol successfully with the yield of 20%. And the further HPLC determination proved most of product were S-2-amino-1 -phenylethanol with e. e. of 90%. Similarly, we did single element experiment for the five element, and got the best condition with temperature of 30℃, pH of 7.0, substrate concentration of 18 mmol/L, baker's yeast amount of 0.22g/ml, glucosamine concentration of 0.2g/ml and time of 30h.The result of our experiment showed that we produced chiral alcohol phenylethanol and 2-amino-1-phenylethanol with high e. e. of 90%, and we achieved the advance aim, which have innovativeness in our country. However, we could see the yield of reaction were 35% and 20%, which was much lower. Consequently, we must upgrade the yield of reaction by improving conditions and mutagenesizing baker's yeast.