Study On Preparation Of The Asymmetric Transformation Resolving Agent-(+)-α-phenylethanesulfonic Acid

(+)-α-Phenylethanesulfonic acid (PES)is an excellent resolving agent, which can be used in the resolution of DL-hydroxyphenylglycine(HPG). (+)-α-phenylethanesulfonic acid can react with DL-hydroxyphenylglycine in an aqueous solution to produce a new chiral salt, which can exist as D-hydroxyphenylglycin(+)-α-phenylethanesulfonic acid and L-hydroxyphenylglyci. (+)-α-phenylethanesulfonic acid. The solubility of L-hydroxyphenylglyci. (+)-α-phenylethanesulfonic acid is 80 times more than the solubility of D-hydroxyphenylglycin (+)-α-phenylethanesulfonic acid. Acoording to this property, the two forms of the salt can be easily separated.α-(+)-PES is a simple chiral compound which has only one chiral center in its molecule structure. The synthetic technics ofα-(+)-PES is novel and the raw material is inexpensive. However, the racemization of PES has never been reported in China. This research mainly focus on the first six parts including the racemization, which is shown as follows:1. Through a large number of literature surveys, a lot of synthetic methods were found out and one of the which was fit for the industrial production was the best one. Furthermore, the influencing factors of each reaction were investigated deeply. PES was prepared through six reactions by styrene and hydrobromide and the lower of the synthetical craftwork's cost , in mild reaction condition and more suitable for industry. And through improving the reaction, the yield of result is contentment. The structures of these production and intermediates were determined by IR, 1HNMR.2. The main reaction factors for the synthesize of 1-phenylethyl bromide such as reaction time, reaction temperature, the proportion of main material, the inhibitior and the dropping velocity of styrene was optimized.Yield of styrene could be up to 89.2%.The method has never been reported.3. The main reaction factors for theα-(+)-PES such as reaction temperature, reaction time, raw material ration, phase–transfer catalyst and stirring speed was optimized. The yield was 65.6%, which was higher than the literature data 44%.4. The key of the whole experiment is racemizatione, which has never been reported in china, but a little mentioned in foreign literature. In our experiment, (-)-α-phenylethanesulfonic acid could be completely racemized. (-)-α-phenylethanesulfonic acid was quite stable in water, HCl, but it was gradually racemized in alkaline aqueous solution. The racemization degree of (-)-α-phenylethanesulfonic acid would be improved with the raise of pH or with the increase of temperature at the same pH in alkaline aqueous solution.5. The purification is innovation in the experiment. In the purification process, water was used as solvent which would not bring impurities to our experiment system and the mother liquor after recrystallization can be recycled. The yield can be obtained 93.7%.6. In the hydrolization process, D-hydroxyphenylglycin(+)-α-phenylethanesulfonic acid was hydrolyzed in aqueous sodium hydroxide.The dropping velocity of the acid and the stirring speed was investigated. The hydrolization yield was 89%, the method has never been reported.