STUDIES ON THE ECONOMICAL MANUFACTURE OF VITAMIN ?? A CONCENTRATE FROM FISH LIVER OIL-XI:ESTERIFICATION OF VITAMIN A CONCENTRATE 3. DIVITAMIN A ESTERS OF PHTHALIC ACIDS

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The work described in this paper was undertaken to find out whether esters of phthalic acids are suitable for economical preparation of crystalline vitamin A ester from concentrate. Phthalic acids used in the experiments included ordinary phthalic, terephthalic and isophthalic. i) Preparation of esters Each of the phthalic acids was converted to acid dichloride and then made to react with vitamin A concentrate respectively as in the previous paper (Bull. Jap. Soc. Sci. Fish. 20, 1027, 1955). Recovery of vitamin A in the esterification was not constant in each test and generally was low (shown in Table 1). The low recovery can be attributed to the presence of acidic monoesters which are produced by the use of excess acid dichlorides. The monoesters cause the loss of vitamin A into water and promote emulsification in the alkali washing procedure. ii) Fractionation of esters The esters thus obtained could not be crystallized. Poor results were also obtained in the fractionation of these esters by solvent distribution, molecular distillation and chromato-graphical adsorption. See Tables 2 and 3. The poor results may be explained as follows. Diesters prepared from a dibasic acid and various alcohols are the mixture of many diesters each having two bindings either of different alcohols or of identical alcohols. Obviously it is difficult to isolate an individual diester from this complicated mixture of diesters similar to each other in properties. In the case of ordinary phthalate, a fraction showing the presence of anhydrovitamin A was obtained. This means that a part of vitamin A is changed into anhydrovitamin A in esterification or subsequent treatments. iii) Preparation and crystallization of synthetic vitamin A terephthalate In order to confirm the supposition that the difficulties in isolation of an ester was due to the presence of other alcohols in the concentrate, synthetic pure vitamin A was made to react with terephthalyl dichloride. In this case, the ester prepared was easily crystallizable. This ester (m. p. 55-56°C, vitamin A potency: 2560, 000 I. U. per gr.) was divitamin A terephthalate (Figs. 1 and 2).
社団法人日本水産学会の論文

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衣巻豊輔
東海区水産研究所

STUDIES ON THE ECONOMICAL MANUFACTURE OF VITAMIN ?? A CONCENTRATE FROM FISH LIVER OIL-XI:ESTERIFICATION OF VITAMIN A CONCENTRATE 3. DIVITAMIN A ESTERS OF PHTHALIC ACIDS

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