摘要:

The rates of thermal decomposition of hydrogen peroxide vapor were measured by the static method at low pressures (0.2 to 20 mm. Hg), over the temperature range 300°–600 °C., in carefully cleaned glass vessels. The reaction was of the first order with respect to time and the final products were only water and oxygen. Around 400 °C. the character of the reaction changed gradually from heterogeneous (surface effects, low activation energy) to homogeneous (reproducible rates in various vessels). With initial pressures of about 10 mm. Hg the experimental rates above 400° lead to an apparent activation energy of 43 kcal. and a frequency factor of 1010.7. After correction for the residual surface decomposition, the rate equation becomesin good agreement with the accepted value for the O—O bond dissociation energy. The reaction rates increased regularly with pressure.Packing the reaction vessels with glass rods and adding various gases (including nitric oxide and propylene) had no appreciable effect on the gas-phase reaction. Deuterium peroxide vapor decomposed at the same rate as hydrogen peroxide under comparable conditions. The results may be explained adequately by the following non-chain mechanism for the uncatalyzed decomposition:

ISSN:0008-4042    

DOI:10.1139/v57-042

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

In order to investigate surface exchange phenomena in detail, a new method, the method of ion exchange autochromatography, has been developed. Its application to the study of finely divided precipitates of strontium sulphate is described.

ISSN:0008-4042    

DOI:10.1139/v57-043

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The readily reducible double bond of gelsemine has been shown to be present in a vinyl side chain and not in an exocyclic methylene group as had been previously assumed. Oxidation of the olefinic double bond in N(a)-methylgelsemine with sodium metaperiodate in the presence of a catalytic amount of osmium tetroxide gave an aldehyde having one carbon less than the starting material. That the product was an aldehyde and not a ketone was proved (a) by conversion to an oxime which was readily dehydrated to a nitrile, and (b) by Wolff-Kishner reduction to a compound containing a C—CH3group not present in the aldehyde itself.

ISSN:0008-4042    

DOI:10.1139/v57-044

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The primary step in the mercury (Hg3P1) photosensitized decomposition of acetone at 55 °C. results in the formation of methyl and acetyl radicals. At least 25% of the acetyl radicals are sufficiently long-lived to suffer collision with a second excited mercury atom, the products being ketene and a hydrogen atom. The primary step in the decomposition of acetaldehyde is at least 95% to form methyl and formyl radicals. The methane found was shown by tracer experiments to be the product of a secondary reaction, probably that between methyl and formyl radicals. Other secondary reactions are discussed.

ISSN:0008-4042    

DOI:10.1139/v57-045

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The hydrogenolysis of methyl α-D-glucopyranoside at elevated temperatures and pressures with copper chromite as catalyst and anhydrous dioxane as solvent was studied. The reaction produced a complex mixture of alcohols, the major components being 2-hydroxymethyl-4,5-dihydroxytetrahydropyran, methanol, isomeric hexanediols, 1,2-propanediol, and ethanediol.

ISSN:0008-4042    

DOI:10.1139/v57-046

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Waste sulphite liquor was studied by chromatographic and ion exchange techniques. A series of chromatographically homogeneous phenolic compounds, which appear to be lignin sulphonate fragments, were separated. Xylose, arabinose, galactose, and rhamnose were isolated and identified by preparation of solid derivatives.

ISSN:0008-4042    

DOI:10.1139/v57-047

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Native vegetable ivory has been found to contain in addition to the mannose also glucose residues together with minor amounts of galactose, arabinose, xylose, and rhamnose units. No pectin could be detected. The native material was very non-uniform and was composed of two major portions (mannans A and B) which differed considerably in their average molecular weight and polymolecularity. Alkaline extraction of the untreated product followed by purification via the copper complex offers the best means for obtaining a pure mannan polysaccharide.

ISSN:0008-4042    

DOI:10.1139/v57-048

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The ratio of the Raman intensity of the trans to gauche bands and also the optical density ratio, forn-alkyl bromides, has been examined in liquid, dilute solution, and vapor (forn-propyl bromide) and the temperature dependence of the Raman intensity ratio obtained over the range −80° to +80 °C. for the liquids. Both Raman and infrared ratios become constant for the higher members of the series but are measurably different forn-butyl andn-propyl bromide. The results are consistent with a very small difference in energy between gauche and trans forms in liquid, solution, or vapor, and can be interpreted semiquantitatively by assuming appropriate trans–gauche energy differences in the carbon chain.

ISSN:0008-4042    

DOI:10.1139/v57-049

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

A method of preparing α-deuterated alkyl nitriles by a base-catalyzed exchange with deuterium oxide is described. The products are convenient starting materials for the preparation of α-deuterated acids and alkyl bromides.

ISSN:0008-4042    

DOI:10.1139/v57-050

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

1,1,1-Trichloroethane-d3has been synthesized from trichloroethylene in four steps via trichloroethylene-d, 1,1,1,2-tetrachloroethane-d2, and 1,1-dichloroethylene-d2.

ISSN:0008-4042    

DOI:10.1139/v57-051

出版商:NRC Research Press    

年代:1957

数据来源: NRC