Study On Purification Of Vitamin A Palmitate

As one of the most important series products of the vitamin A, Vitamin A palmitate is a kind of material that is indispensable to normal body metabolizes for humans and animals. Vitamin A palmitate functions in vision, cell differentiation, immune response and also embryonic development. It is widely used in the food, cosmetics, pharmaceuticals and feed additive. The synthesis of Vitamin A palmitate by chemical methods now occurs in industry. As an alternative, the use of lipases to catalyse these synthesis reactions has recently become a much more promising method. Lipase-catalyzed reactions are superior to conventional chemical methods owing to mild reaction conditions, high catalytic efficiency, and the inherent selectivity of natural catalysts which results in much purer products and the foreground that good industry amplification. In this paper, the method for separation and purification of vitamin A palmitate was investigated.According to the characteristic of chemical constitutes, in the systems of enzymatic synthesis of vitamin A palmitate by transesterification, a separation process of vitamin A palmitate was submitted and the optimal process conditions were studied. The palmitic acid was neutralized by NaOH(s) and 98%of palmitic acid could be removed. After removed of palmitic acid, the solution was filtered and distilled under reduced pressure. The residue was washed by methanol for the separation of vitamin A acetate and vitamin A palmitate. The optimal conditions were:the residue was washed by15mL methanol per gram vitamin A acetate for2hours, the optimal temperature was30℃. The purity of vitamin A palmitate was above95.5%, the purity of the vitamin A palmitate obtained was85%and the acid number was below2mgKOH·g-1.The method of preparation of vitamin A was studied. One gram vitamin A acetate was dissolved in15mL methanol and hydrolyzed for1hour by0.3mL12.5mol·L-1NaOH. The hydrolysate was extracted by50mL Petroleum ether and15mL H2O. The organic layer was washed by3volume H2O and the vitamin A solution was prepared.According to the characteristic of chemical constitutes, in the systems of enzymatic synthesis of vitamin A palmitate by esterification, a separation process of vitamin A palmitate was submitted and the optimal process conditions were studied. The technics was easy and feasible. The method and the optimal conditions were as follows:after that the solution was distilled under reduced pressure, the residue was washed by15mL methanol per gram vitamin A acetate. The methanol was added in batches and the mixture was stirred for30minutes. The optimal temperature was30℃. The purity of vitamin A palmitate was above96%, the purity of the vitamin A palmitate obtained was90%and the acid number was below2mgKOH·g-1.The pure product was flaxen oil with special smell and identified by HPLC, IR spectra, MS,1H NMR and13C NMR.