Study On Catalytic Hydrogenation Of α-alanine

As an important intermediate to synthesize laevorotatory levofloxacin, the need for L-alaniol is increasing in recent years whose optical purity and price have an immediate influence on the quality and cost. But the synthetic route before is so complicated that lead to the rise in cost. Therefore groping the new synthetic method of L-alaniol receives high attention.The experiment utilizes the method of catalytic hydrogenation which is different from the traditional synthetic method. In this paper, aqueous phase hydrogenation of L-alanine was performed in a three-phase, stirred batch reactor. The catalyst used for this hydrogenation was 5 wt% ruthenium on carbon. The effects of the temperature, pressure, acid type and phosphoric acid concentration on the conversion rate are discussed. The method of reduced pressure distillation was used to separate and purify the product. The product was qualitatively and quantitatively analyzed by gas chromatography and spectrophotometer. With increase of the temperature and pressure and catalyst amount, the conversion rate increase. When acid concentration is low, the conversation rate increases with the increase of the concentration. When acid concentration is high, the conversation rate decreases with the increase of the concentration.Based on the research above mentioned, the optimum reaction conditions were obtained as follow: the temperature 413K, the pressure 7MPa, the phosphoric acid concentration 0.29mol/L and the concentration of L-alanine 0.22mol/L. Under optimal conditions 60.5% alanine conversion with 59.8% alaninol yield was achieved.