抄録
In the previous paper, the influence of water contents on the stability of vitamin A aldehyde in aqueous ethanolic solutions was reported. Similar investigations were carried out on vitamin A aldehyde in various alcohols and other water soluble organic solvents, and the results are discribed in this paper. Vitamin A aldehyde solutions in absolute or 80% aqueous solvents were stored at 50℃. The remaining rates of vitamin A aldehyde and the yield of vitamin A acetal were estimated by spectrophotometric methods. Vitamin A aldehyde was stable in 80% aqueous alcoholic solution (in isopropanol, n-propanol, ethanol and methanol). Vitamin A aldehyde was converted into vitamin A acetal in absolute methanol, ethanol and n-propanol, whereas it was not converted in absolute isopropanol. Vitamin A aldehyde was more stable in absolute dioxane and tetrahydrofurane than in the corresponding 80% aqueous solvents. In dimethylformamide, vitamin A aldehyde was stable in both absolute and 80% aqueous solvents. Properties of vitamin A acetal prepared in absolute methanol were examined by mass, NMR and IR spectrometry. In absolute methanolic solution, the majority of vitamin A aldehyde was converted into vitamin A acetal after 14 days at 50℃. In 80% aqueous methanolic solution, vitamin A acetal was rapidly reversed into vitamin A aldehyde.
