醗酵によるVitamin Cの製造

Abstract

In the previous reports, it was ascertained that Pseudomonas fluorescens sp. isolated by the author produced a large amount of 2-keto-L-gulonic acid from Ca-D-idonate (containing a half quantity of Ca-D-gluconate) and that the separation of 2-keto-L gulonic acid from 2-keto-D-gluconic acid which produced simultaneously from Ca-D-gluconate was achieved by using the difference of the solubility of their Na-salt in methanol. Now, the author intended about the synthesis of vitamin C from Na-2-keto-L-gulonate thus obtained. The summary of the results is as follows: 1. Free 2-keto-L-gulonic acid crystal was obtained with ca. 80% yield from its Na-salt. 2. The optimum temperature for the methyl esterification of 2-keto-L-gulonic acid was 48_??_50° in 30 minute reaction and the yield of methyl ester crystal was 83.01 by the REICHSTEIN's method. Then the methyl ester was converted to vitamin C by heating with weak alkalic solution and after removingmetallic cations with the ion-exchange resin. The yield.of the vitamin C was about 90%. 3. Vitamin C was also prepared directly from free 2-keto-L-gulonic acid by the process of author's modification of the REICHSTEIN's method, viz using benzol instead of chloroform and butanol instead of ethanol as HCl-gas absorbing agent. The yield of vitamin C crystal was ca. 77% (93% purity). (The original REICHSTEIN's method gave 801 (95;o purity) yield from diacetone-2-keto-L-gulonic acid.)