The preparation of a number of a-and p-monoglycerides and the behaviour of the compounds in question towards periodic acid is described.With a view to an investigation of the migration of the acyl group in monoglycerides in acid medium (performed in [1950][1951] , about which a detailed publication is soon to appear 1, we had to have at our disposal a widely varied series of a-and firnonoglycerides of great purity. Below we are giving a description of the preparation of the monoglycerides involved in some way or another in the work in question, most of which monoglycerides were still unknown, and of the determination of their purity by means of periodic acid*. Preparation of the a-monoglycerides.Practically all the monoglycdides af thh type were obtained by the method of Fischer, Bergmann and Biitwind 8 , i.e. by acdation of a~-&mpmpyh&neglyced ("acetone glycerol") with the aid of the re@red acyl chloride or acyl bromilde in the prwence o f an excess of dry pyridine and hydrolysis of the y"acyl-a~-isoprapyEideneglycerol &us formed with dilute hydrochloric acid.The description uf the preparation of a-monobenzoylg.lyceral given below is ,meant to serve as an example of our standard procedure. Unless otherwise stated, the preparation af the other a-monoglycerideis taok place in t3e same way.
Lorsqu'on enlève de l'acide bromhydrique au 3‐bromo‐4‐hydroxy‐thiacyclopentane‐1,1‐dioxyde (III), on peut obtenir des produits différents selon le procédé que l'on utilise. En se servant du carbonate de baryum pour fixer l'acide bromhydrique, les auteurs ont obtenu un époxyde (V). L'anneau époxyde est ouvert par chauffage avec les hydracides halogénés, l'acide acétique et l'eau. En utilisant la pyridine pour éliminer le brome de l'alcool bromé (III), on obtient l'alcool non saturé IV, qui s'isomérise sous l'influence d'alcali. Nous considérons le produit isomérisé comme le dimère XII, dérivé du dioxane.
For the glycerol-monoiodohydrins of m.p. 48-49' and 53.5-54.5" new methods of preparation are described, The last-mentioned compound has thus become reasonably accessible for the first time. The statemen,ts in the literature as to the constitution of the first-mentioned compound are discussed. Unambiguous evidence for the constitution of the two compounds is furnished: the compound of m.p. 4 8 -4 9 " is the a-isomer, that of m.p. 53.5-54.5'the !-isomer.A glycerol-monoiodohydrin of m.p. 48-49' was first prepared by Liiders 1 ) by heating glycerol-monochlorohydrin with suitable inorganic iodides, and was brought out under the name of "Alival". The starting material was, without any argumentation, stated to be the sc-chlorohydrin: hence the iodine compound thus obtained was from the very first considered to be glycerol-a-monoiodohydrin. What was evidently the same compound was obtained by Fischer and Pfahler z) upon heating the acetone compound of glycerol-monochlorohydrin, the latter prepared by hydrolysis of epichlorohydrin with water, with sodium iodide in alcoholic solution to 1W0: the alcohol or the sodium iodide must have contained water. Further the compound was obtained by Glattfeld and Klaass), who heated crude glycerola-monochlorohydrin, containing some &isomer, with sodium iodide in acetone solution to 100' (?).These methods of preparation are not very satisfactory. W e have now found that the compound in question can be obtained readily and in a good yield by the action of a concentrated hydroiodic acid solution
2‐Methylbutene‐1, 2‐methylpentene‐1, and 2,3‐dimethylbutene‐1 were polymerized by AlCl3 or AlBr3 catalyst in ethyl chloride or ethyl chloride—vinyl chloride mixtures at temperatures down to —175°C. The glass transition temperatures of the amorphous polymers are −5, 27, and 37°C., respectively. The highest molecular weights—weight averages about 200,000 to 350,000—were found at the lowest polymerization temperature and with monomer—catalyst molar ratios of about 1000 and over. The influence of the addition of the corresponding 2‐methylalkene‐2 was investigated for the polymerization of 2‐methylbutene‐1 and 2‐methylpentene‐1. The other alkenes investigated, viz., 2,3,3‐trimethylbutene‐1, 2,4,4‐trimethylpentene‐1, and 2‐ethylbutene‐1, yielded only small amounts of liquid oligomers. In the polymerization of 2,3‐dimethylbutene‐1 an extensive intramolecular 3–2 hydride shift occurred, varying in amount from 80% at −125°C. to 100% at −175°C., to judge from NMR and infrared spectra. Of the methylenecycloalkanes investigated, only methylene—cyclohexane yielded a high molecular weight polymer—weight average molecular weight about 100,000—although in a yield of only a few per cent, under optimal conditions at −180°C. Methylenecyclobutane gave a semisolid polymer of low molecular weight, methylenecyclopentane a small amount of liquid oligomers, and 2‐, 3‐, and 4‐methyl(methylenecyclohexane) solid polymers of low molecular weight. Poly(methylenecyclohexane) and the polymer from 4‐methyl(methylenecyclohexane) crystallized from solution or upon thermal treatment; the crystalline melting points were about 210 and 195°C., respectively. The relation between structure and ease of polymerization of this type of unsaturated aliphatic hydrocarbon is briefly discussed.
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