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  • 1980-1984
  • 1960-1964  (6)
  • 1963  (6)
  • Alkenes  (3)
  • Gas chromatography  (3)
Datenquelle
Materialart
Erscheinungszeitraum
  • 1980-1984
  • 1960-1964  (6)
Jahr
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Permethylation of Oligomeric and Polymeric Carbohydrates and Quantitative Analysis of the Cleavage Products (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 515-523 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Permethylation ; Carbohydrates ; Methylation ; Gas chromatography ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Methylation of mono-, oligo-, and polysaccharides with methyl iodide/barium oxide or dimethyl sulfate/barium hydroxide in dimethyl sulfoxide as solvent rapidly leads to high degrees of methylation. Depending on the structure and solubility of the substrate, permethylation can be achieved either in one operation or by repetition of the same treatment. Procedures of permethylation of various carbohydrates are given. The methyl glycosides obtained on methanolysis can be separated and determined quantitatively by gas chromatography. The preparation of separating columns with minimum retention for this purpose is described. Pullulan was shown to have the structure of a completely linear polymer of maltotriose units connected by α-1→6-linkages. - In addition the gaschromatographic identification of methyl ethers of glucosamine and galactosamine is reported.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196305151
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  • 2
    Digitale Medien
    Digitale Medien
    Type and Extent of Isomerization of Straight-Chain Mono-olefins during the Koch Carboxylic Acid SynthesisReported in part at the meeting of the Gesellschaft Deutscher Chemiker, Aachen 1961; Angew. Chem. 73, 767 (1961). (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 719-722 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Koch carboxylic acid synthesis ; Carboxylic acids ; Alkenes ; Isomerization ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: When straight-chain mono-olefins, from pentene to decene, are subjected to the Koch carboxylic acid synthesis by the addition of CO and H2O or CH3OH in the presence of strongly acidic catalysts, not only the expected secondary acids, but also mixtures of a specific type of tertiary acids or their methyl esters are formed. When the catalysts contain boron trifluoride, the secondary acids are formed in ratios of isomers which are, within the scope of this investigation, independent of the experimental conditions and which agree well with the values calculated from the isomer equilibria of the corresponding n-olefins. Using concentrated sulfuric acid as catalyst, a larger proportion of tertiary acids is obtained than with BF3-catalysis, and amongst the secondary acids, those isomers predominate in which the COOH group is situated near the centre of the molecule.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196307191
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  • 3
    Digitale Medien
    Digitale Medien
    Modern Methods for the Separation and Continuous Measurement in the Gas Phase of Compounds Labelled with Radiocarbon. Radio and Reaction Gas ChromatographyAlso Part VI of the series on Reaction Gas Chromatography. Part V: F. Drawert and G . Kupfer, Hoppe-Seylers Z . physiol. Chem. 329, 90 (1962). (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 540-545 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Radiocarbon ; Gas chromatography ; Trace analysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In biochemical work with isotopic tracers, it is frequently advantageous to investigate samples in the gas phase. In this way, the selectivity of gas-chromatographic separating columns and the sensitivity of detectors can be utilized for both the detection of gas-chromatographic fractions and the determination of their radioactive portions. Conversion of materials separated by gas chromatography into a single standard chemical compound prior to measurement of the radioactivity is recommended. Methods suitable for 14C-labelled compounds can also be applied to those labelled with 3H or 35S.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196305401
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  • 4
    Digitale Medien
    Digitale Medien
    Gas Chromatographic Investigation of Racemization during Peptide SynthesisPresented in brief at the Fifth European Peptide Symposium in Oxford, England, in September, 1962.Respectfully dedicated to Prof. Dr. Adolf Butenandt on the occasion of his 60th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 183-188 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Racemization ; Peptide synthesis ; Gas chromatography ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It is shown that the methyl esters of many diastereoisomeric N-trifluoroacetyldipeptides can be separated by gas chromatography on Golay columns. This makes it possible for the first time to carry out accurate quantitative investigations of recemization occurring during peptide synthesis without resort to measurements of optical rotation or enzymatic cleavage, and witout having to isolate the peptides. Some well-known methods of forming peptides were examined using the synthesis of the methyl ester of carbobenzoxy-L-valyl-L-valine as an example. The synthesis of the methyl ester of N-trifluoroacetyl-L-valyl-L-valine was investigated as a model for the linking of peptides. The influence on racemization of numerous factors was determined. General conclusions could be drawn regarding peptide synthesis.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196301831
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  • 5
    Digitale Medien
    Digitale Medien
    Emulsion Polymerization of Vinyl Monomers under the Influence of Ionizing Radiation (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 295-308 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Emulsion polymerization ; Polymerization ; Polymerization ; Alkenes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ionizing radiation induces the polymerization of some vinyl monomers in aqueous emulsion with high radiation yields. With identical emulsion compositions, the kinetics of this reaction and the kinetics of emulsion polymerization induced by water-soluble initiators are very similar. The rate of reaction in emulsion polymerization is about one hundred times greater than in bulk polymerization. The initiation of emulsion polymerization by means of ionizing radiation permits uniform “illumination” of the reacting volume, as well as almost any desired variation in the frequency of initiation during the reaction. The sharp decrease in the overall rate of reaction when initiation is interrupted during emulsion polymerization of styrene induced by γ-rays contradicts the earlier concept of sharply separated reaction zones.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196302951
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  • 6
    Digitale Medien
    Digitale Medien
    Reactions of Olefins with the Titanium-Carbon BondDedicated to Prof. Dr. Karl Ziegler on the occasion of his 65th birthday (1963)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 2 (1963), S. 704-714 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Titanium ; Alkenes ; Polymerization ; Titanium ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: At low temperatures, ethylene and α-olefins (Δ1-olefins or 1-alkenes) are rapidly converted into oligomrs by the two-component organometallic catalyst CH3TiCl3·CH3AlCl2. To achieve smooth oligomerizations, aromatic or chlorinated hydrocarbons must be used as solvents. Although the activity of the titanium-carbon bond is enhanced by the aluminum component of the catalyst, the aluminum and its methyl group do not participate in the reaction proper; the latter proceeds exclusively at the titanium-carbon bond. The reaction will olefins can be used as an analytical method for the quantitative determination of the titanium-carbon bond in admixture with the organoaluminum component. It is thus possible to follow the reaction leading to formation of the catalyst from titanium tertrachloride, as well as the processes occurring at the titanium-carbon bond during the oligomerization of olefins. All the observations indicate that the catalyst possesses an ionic structure which is determined by the solvent. It is shown that the initial reaction step probably involves formation of a complex between the olefin and the alkyltitanium cation. The reaction scheme proposed is based on organometallic reactions which are characterized by carbanion and hydride transfers within the olefin-cation complex. This mechanism, which is unusual for Ziegler catalysts, is due to the predominance of hydride transfers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196307041
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