The Preparation Of Optically Active 1-phenyl-1,2-ethanediol

Chiral diols have special properties in optical, thermo and chemical stability. They are not only the indispensable chiral additives, but also very important intermediates for synthesis of the optically active medicines, pesticides and functional materials, therefore successful synthesis of optically active 1-phenyl-1; 2-ethanediol may have the practical significance in medicinal industry. In this paper, we study the preparation of optical active 1-phenyl-1, 2-ethanediol by biocatalysis and biochiral separation.Our experiments are started withα-hydroxyacetophenone to synthesize (R)-1-phenyl-1, 2-ethanediol by biocatalysis and asymmetrical reduction. First we synthesizedα-bromoacetophenone and optimized reaction condition to make the rate of production about 91.2%. Then we synthesizedα-hydroxyacetophenone by microwave synthesizer withα-bromoacetophenone as starting material, which is the substrate of biocatalysis. Furthermore, we investigated the factors that affect the rate of production by the orthogonal tests. The results turned out that the most important factor is pressure of reaction system, the second factor is irradiation time and the least factor is the concentration of starting materials. Afterwe optimized the condition of reaction by microwave synthesizer, 85.8% of production yield is achieved. Finally the (R)-1-phenyl-1, 2-ethanediol is synthesized by asymmetrical reduction ofα-hydroxyacetophenone with yeast. The optimal conditions for synthesis of (R)-1-phenyl-1, 2-ethanediol is reaction time: 28 hours, reaction temperature: 33oC and pH value of buffer: 6.5. The ee value is 92.1% measured by HPLC and the rate of conversion is 96%. We also used another two methods to synthesize the substrate 1-phenyl-1, 2-ethanediol, which can be separated by biological separation. In method one, 1-phenyl-1, 2-ethanediol is synthesized by catalytical hydrolysis of styrene oxide. After we optimized reaction condition, the production yield is close to 97.2%. In method two, firstly we synthesized 1, 2-dibromo-1-phenylethane with styrene and bromine as starting materials, and then obtained 1-phenyl-1, 2-ethanediol by hydrolysis of 1, 2-dibromo-1-phenylethane in alkaline medium. After we optimized reaction condition, the total production yield is close to 70.2%. Finally, (S)-1-phenyl-1, 2-ethanediol was obtained with deracemization of 1-phenyl-1, 2-ethanediol by using Candida parapsilosis under condition of amount of cells: 5%, substrate concentration: 0.8%, pH value: 6.5, temperature: 33oC and reaction time 48 hours. The enantiomeric excess of (S)-1-phenyl-1, 2-ethanediol was 99% by HPLC and the conversion rate was 88%.