Study On The Synthesis Of L-Carnitine

L-carnitine is also called Vitamin Bt and is the fundamental element of Microbes,animals and plants.It has many physiological functions and can cause many diseases when defected. Many studies are finding its preparing methods since it was identified as an important nutriment. Among them , asymmetric syntheses and microbe trasformation are the hot thesis. Ethyl 4-chloroacetoacetate may be asymmetric reduced to ethyl R-4-chloro-3-hydroxybutyrate and ethyl S-4-chloro-3-hydroxybutyrate, which are both important chiral intermediates. S-CHBE is an important chiral intermediate of Amlodipine which is often used to do with hypertension and angina. R-CHBE may be used to prepare L-carnitine. It has many benefits asymmetric reducing COBE with microbes to prepare L-carnitine. The baker`s yeast (Candida sp. 118 Saccharomyces bayamus,103 Saccharomyces cerevisiae,106 Saccharomyces cerevisiae,123 Saccharomyces cerevisiae)used in the experiment were provided from college of resources &environment, Northwest Sci-tec university of A&F. With methods of microbe culturing, yeast screening, culture conditions opitimizing, we picked out three yeasts having asymmetric reduction capacity. We optimised its culture conditions to improve the rate of production and optical purity, thus getting R-CHBE, then L-carnitine. The results is showed bellow: 1. Screening out three yeasts that can asymmetric reduce COBE to S-isomer. They are 103 alcohol yeast, 106 beer yeast, 123 flour yeast. 2. In 4 vessels of 250mL,putting in 100mL sterilized water, 8g wet cell, 0.2g COBE, respectively, using 5g glucose, sucrose, D(+)gluconie acid d-lactone, ethanol respectively as assistants, at 32 ℃,cradle rotating speed 120rpm/min, to find out the effects of various assistants on CHBE rate of productivity and enantiomer excess.It indicates that sucrose is the best assistant to prepare S-isomer. 3. To 106 beer yeast, it can reduce COBE to R-isomer when using D(+)gluconie acid d-lactone as assistant. 4. The changing concentration of COBE causes various influences on the three yeasts, and the three yeasts are suited to different COBE concentration scales. To 123 yeast, the rate of productivity reaches its highest point when COBE concentration is 14.8mmoL/L. To 106 yeast, when COBE concentration is bellow 30mmoL/L, concentration has minor effect on rate of productivity. Then as concentration increases, the rate of productivity decrease. To 103 yeast, the rate of productivity improves as the concentration of COBE increases, while its rate of productivity is not high at all. 5. Considering rate of productivity and optical purity, the suitable reaction temperature to the three yeasts is 32℃. 6. When assisted with D(+)gluconie acid d-lactone and with low COBE concentration (0.1g/100mL), 106 yeast can reduce COBE to CHBE with an enantiomer excess of more than 98%.