Synthesis Of Amino Acids Esters And Their Derivatives

Amino acids esters and their derivatives, of which the synthesis has rapidly become a new research field in recent years, have been extensively used as medical semi-product, food additives, cosmetic additives, mineral flotation additives, germicides, etc. So research on the synthesis of amino acids esters and their derivatives are of great significance both in theoretical and in practical side.Preparation technologies of a series of amino acids esters were studied systematically, then the synthesis of N-benzyl glycine ethyl ester hydrochloride and cycloserine was also studied using glycine ethyl ester hydrochloride and L-serine methyl ester hydrochloride as raw material respectively in this paper. Final products were characterized by melting point determination, rotation determination, IR, element analysis, 1H-NMR and HPLC and their main qualities correspond to the related standards.Esterification of amino acids using thionyl chloride affords twelve amino acids esters hydrochloride, such as L-serine methyl ester hydrochloride, glycine ethyl ester hydrochloride, L-valine methyl ester hydrochloride, L-phenylalanine ethyl ester hydrochloride, L-tyrosine ethyl ester hydrochloride, etc. The influentical factors on the synthesis of L-serine methyl ester hydrochloride with thionyl chloride were studied and optimized. The final yield was up to 85.0% and puritiy was more than 98.0%. The other synthesis technology, esterification of L-serine using strong acid resin as catalyst was studied as well. In the optimum reaction condition, the yield was up to 62.0% and puritiy was more than 98.0%. Theses two technologies were analyzed and summarized.N-benzyl glycine ethyl ester hydrochloride was prepared from glycine ethyl ester hydrochloride. Glycine ethyl ester hydrochloride reacted with benzyl chloride to give N-benzyl glycine ethyl ester in the presence of alkali, which then was treated with hydrochloric gas to afford N-benzyl glycine ethyl ester hydrochloride. The effects of stuff molar ratio, reaction time and tempreture on the yield were studied. The final yield was up to 61.0% and purity was more than 99.0%.Cycloserine was produced using L-serine methyl ester hydrochloride as raw material. L-serine methyl ester hydrochloride was chloridized with phosphorus pentachloride to afford 2-amino-3-chloride propanic acid methyl ester hydrochloride, which was cyclized with hydroxylamine in the presence of alkali to give cycloserine. The conditions of chlorination and cyclization were optimized in each step of reaction. The total yield of cycloserine was 46.7% and purity was more than 99.0%. The route laid an elementary foundation for the study of D-cycloserine synthesis.