Isolation of Vitamin A

Abstract

FOLLOWING closely on the announcement of the probable preparation of vitamin D by several independent workers (NATURE, Jan. 9, p. 50), come two announcements of the isolation of a substance which prima facie appears to be the long-sought vitamin A. In a paper published in the issue of Helvetica Chimica Acta for December 1931, Prof. P. Karrer, of the University of Zurich, together with B. Morf andK. Schöpp, describes the isolation and purification from the unsaponifiable fraction of the liver oil of the skipper (Scomhresox saurus) of an alcohol having the formula C20H30O or C22H32O, optically inactive, and possessing the molecular weight 300-320. Esters of acetic and p-nitrobenzoic acid were prepared, and the alcohol gave geronic acid on oxidation with ozone. The same substance was obtained by a special method from the liver oil of the halibut (Hippoglossus hippo-glossus). In an address on “Recent Progress in the Chemical Study of Vitamins”, given to the London Section of the Society of Chemical Industry on Jan. 4, Prof. J. C. Drummond stated that he, in collaboration with Prof. I. M. Heilbron and Dr. B. A. Morton, had succeeded in isolating, by a process of fractional distillation, a very potent fraction from the unsaponifiable residue of the liver oil of the halibut. The substance is a heavy, viscid oil of a slightly yellow colour; it is an alcohol, its formula is probably C20H30O, and its vitamin potency is of the same order as that of the recently discovered ‘calciferol’. Sufficient work has not yet been done to enable us to say that the substance is pure vitamin A, but it seems very probable that its purity is approximately ninety per cent.