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Natural c-tocopherol has been shown to differ from synthetic 5methyltocol, with which it had previously been identified. Spectroscopical, chromatographical, synthetical, and degradative evidence is presented confirming the nature of the synthetic compound. &-Tocopherol would appear to be a 5,8-disubstituted chromanol, related to the tocols, but perhaps with altered substitution at C(2). Natural c-tocopherol from wheat bran is not identical with 5,7-dimethyltocol, which structure had been given it, but appears to be the trisubstituted representative in the same series as E-tocopherol. The <-tocopherol that occurs in rice, however, is apparently identical with authentic 5,7-dimethyltocol.WHEN McHale, Mamalis, Marcinkiewicz, and Green's synthetic 5-methyltocol l was converted into a nitroso-derivative by Quaife's method and this compound compared chromatographically with the nitroso-derivative of natural E-tocopherol the Rf values of the two compounds were different. Since c-tocopherol has been identified with 5methyltocol, it was necessary to compare in detail the chemistry of the two compounds.Eggitt and Ward considered that &-tocopherol was 5-methyltocol because, on partition chromatography (a system sensitive to molecular-weight differences) , it migrated almost identically with 8-methyltocol. This was also the view of Green, Marcinkiewicz, and Watt: who found that the substance migrated in a two-dimensional adsorption-partition chromatographic system to the same position as 7-methyltocol. Eggitt and Nonis 6 compared the behaviour of E-tocopherol with that of other tocopherols and concluded that &-tocopherol was probably 5-methyltocol, from the failure of the former to enter coupling reactions, its formation of a nitroso-derivative whose ultraviolet and visible spectra were closely similar to those of the nitroso-derivative of 5,8-dimethyltocol, the nearly Part IV, preceding paper.

The preparation of some amino-oxyalkanes and their corresponding di-A sum-guanides, together with certain arylmethyl analogues, is described. mary of bacteriostatic activities is included.

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A series of isothiourea derivatives of 6-phenyl-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole (tetramisole) is described. The compounds are prepared by the S-alkylation of the thioureas that were obtained either by the reaction of an amine with 6-(3-isothiocyanatophenyl)-2,3,5,6-tetrahydroimidazo[2,1-b] thiazole or by the reaction of an isothiocyanate with 6-(3-aminophenyl)-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole. These derivatives have an improved spectrum of activity over tetramisole and are active against nematodes, cestodes, and trematodes. The structure-activity relationships are discussed.