Abstract
When the solid part of acetylated unsaponifiables from pollack viscera oil was distilled at 2 mmHg, a considerable amount of needles (m.p. 78°C) was obtained from the distillate up to 238°C and they were identified as cholesta-3, 5-diene by the estimation of elemental composition, molecular weight, rotation and ultraviolet absorption spectrum (Fig. 1). This substance, however, was proved to be an artefact due to the pyrolysis of cholesteryl acetate, as the hydrocarbon was not detected in the same unsaponifiables from pollack viscera oil, when for fractionation the alumina column chromatography was applied instead of distillation procedure. As shown in Table 1, on the other hand, cholesteryl acetate was found to decompose easily on heating without any catalyst and to give cholesta-3, 5-diene in good yield. The pyrolysis temperature was considerably lower than the recorded ones on cholesterol or other cholesteryl derivatives.
