水産動物内臓油利用に関する研究-V : 濃縮ビタミンAエステル製造の工業化研究(その1)
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The process for manufacturing vitamin A acetate comprising acetylation of a concentrated preparation of vitamin A alcohol obtained from natural liver oil was examined of its industrial practicability. In the present examination of esterification reaction, a concentrated preparation of vitamin A alcohol was subjected to reaction with acetic anhydride in the presence of anhydrous sodium carbonate, the formation of vitamin A acetate being promoted by constantly removing the by-produced carbondioxide under a reduced pressure. As seen from the results shown in Tables 1, 2 and 3, which were obtained by carrying out the esterification under various reaction conditions, the esterification was found to advance to a satisfactory extent when acetic anhydride and anhydrous sodium carbonate were used in amounts greater than 45% and 25%, respectively, based on the weight of vitamin A alcohol employed, under the application of a reaction temperature of 20°C and a reaction time of 4-5 hours. The set of reaction conditions thus found as experimental satisfaction was further examined of its industrial applicability by confirmatively carrying out the acetylation on a large scale with concentrated preparations of vitamin A alcohol obtained from liver oil of various sources (see Table 4). The values found for total yield of vitamin A being as high as above 97%, gave promise of industrial adoptability of the acetylation as a means of obtaining a concentrated preparation of vitamin A notably improved in stability. The vitamin A acetate thus tentatively prepared on an industrial scale was crystallized by dissolving in ethylformate and treating in accordance with the procedure shown in Fig. 1 into pale yellow prisms of a high grade of purity and having a vitamin A concentration of 2, 832, 000 USPU/g, the yield of vitamin A proving to be 37.11%. These crystals were not only proved to be of high purity but identified by examining their physicochemical properties inclusive of infrared absorption in reference to the data in literature (see Table 5) to consist of vitamin A acetate in trans-form.
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