| 摘要 |
1527909 Isomerizing vitamin A compounds F HOFFMANN-LA ROCHE & CO AG 11 Nov 1975 [12 Nov 1974] 46529/75 Heading C2V Vitamin A compounds which are all-trans, 9-cis, 11-cis, 9,11-di-cis or mixtures thereof, are isomerized in liquid form or as at least 3% (wt./vol.) solutions with light of wavelength between 240 and 450 n.m. in the absence of sensitizers. In examples solutions of isomers of vitamin A acetate, vitamin A alcohol, vitamin A aldehyde and vitamin A palmitate, are isomerized, the solvents being n-hexane, npentane, ethanol, isopropanol, chloroform, ether, acetone and acetonitrile.
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