VITAMIN E 345 



in foods and the extreme smallness of the amounts needed for its special 

 functions. 



Physical and Chemical Properties 



In a report to the National Academy of Sciences on April 25, 1925, 

 Evans and Burr (1925a) summarized their findings concerning the 

 physical and chemical characteristics of vitamin E as f ollov^^s : 



"The vitamin may be called fat soluble, though its range of solubility is far 

 greater than that of ordinary fats. While this range of solubility may really be 

 due to the solubilities of impurities as yet associated with the vitamin, it is a 

 fact that the most concentrated fractions yet obtained have been almost completely 

 miscible with solvents representing such a range as methyl alcohol, ethyl alcohol, 

 ether, pentane, benzene, acetone, ethyl acetate, carbon disulfide and so forth. The 

 vitamin is almost insoluble in water, yet we have repeatedly encountered its pres- 

 ence in water solutions. There is enough left in the water after precipitation of 

 calcium soaps, for instance, to be extracted with ether and effect cures. The dis- 

 tribution ratio between water and ether is very large, for a few extractions with 

 an equal volume of ether effect quantitative removal. This has been established 

 by a large number of feedings of the non-saponifiable fraction, the residual soap 

 always failing to produce fertility. The solubility of "E in such substances as 

 alcohol and pentane shows a large temperature coefficient and is so much greater 

 than some of the contaminating substances, the sterols, for example, as to permit 

 separation of the vitamin from them. 



"Vitamin E is remarkably stable to heat, light, air, and many of the ordinary 

 chemical reactions. As regards temperature, while the ashing of wheat germ com- 

 pletely destroyed the vitamin, yet heating of the germ to 170° C. so that it was 

 greatly charred left the E unimpaired. Distillation of wheat germ oil, or a fraction 

 out of it, in superheated steam at 180° C. for several hours has not destroyed it. 

 Distillation in vacuo up to 233° C. has not, in fact, caused any lowering of the 

 potency of the fractions so treated, nor have any physical changes like changes 

 in solubility been detected. We have not encountered evidence that daylight affects 

 E in wheat germ oil, but there would appear to be partial destruction by exposure 

 in thin layers to a powerful quartz mercury lamp for one hour. As regards oxida- 

 tion, exposure of wheat germ oil for as many as twelve hours to a stream of 

 air washed with acid and alkali, and at 97° C, has not destroyed E. At normal 

 temperatures the vitamin is remarkably stable to both acid and alkali and many 

 chemical treatments. It dissolves unchanged, for instance, in saturated alcoholic 

 hydrogen chlorid. W"e have hydrogenized wheat germ oil in the presence of 

 palladium at 75° C, and no injury to the vitamin resulted. Further, alcoholic 

 extracts of Crisco, a hydrogenization product of cottonseed oil. are always fairly 

 rich in the vitamin. We have treated the germ oil with both 20 per cent hydro- 

 chloric acid and one-tenth normal acid for twentj" hours at room temperatures 

 without destruction of the vitamin. It is not destroyed by concentrated sulfuric 

 acid. It resists the action of boiling 20 per cent alcoholic potassium hydrate, 

 though partial destruction would appear to occur on very prolonged hot saponifi- 

 cation. The saponification with 20 per cent alcoholic potassium hydrate can be 

 carried out at 30° C. without great loss of the vitamin which goes into the non- 

 saponifiable quota, 5 per cent of the oil, so that by this step alone a notable 

 concentration of E is always attained. The non-saponifiable quota is, in turn, 

 chiefly (73 per cent) sitosterol, which is largely insoluble in pentane in the cold, 

 an excellent solvent for vitamin E, which, together with pigments and other 

 materials, can thus be washed out of the sterols, leaving them white. The sterols 

 are inactive. If the orange-red viscous oil obtained from the pentane is treated 

 with methyl alcohol, more extraneous material is removed, and the vitamin goes 

 into the alcohol portions which now can be mixed with petroleum ether or diluted 

 to 90 per cent methyl alcohol, allowing an immediate separation into two layers, 

 the petroleum ether invariably securing more of the vitamin, in fact, all of it, 



