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  • 1985-1989
  • 1960-1964  (5)
  • 1880-1889
  • 1964  (5)
  • 1886
  • Catalysis  (3)
  • Radical reactions  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Intramolecular Free-Radical Reactions (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 525-538 
    Details
    ISSN: 0570-0833
    Keywords: Radical reactions ; Free radicals ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present article an attempt is made to summarize the steric requirements and the influence of neighboring groups which determine the course of intramolecular radical reactions. Steroids are used as substrates for these reactions, since here the spatial arrangement of the ring members and the distances between substituents are largely fixed. Furthermore, intramolecular free-radical reactions are of practical importance in steroid chemistry in connection with substitution at non-activated carbon atoms. Almost all the reactions discussed begin with the formation of an oxygen radical by oxidation of an alcohol with lead tetraacetate or by homolysis of the corresponding hypoiodite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196405251
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Free Radicals and Free-Radical Reactions of Monovalent and Divalent SulfurFree-radical reactions of tetra- and hexavalent sulfur are not considered in this work. For a survey of these reactions, see [16], p. 326. (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 602-608 
    Details
    ISSN: 0570-0833
    Keywords: Free radicals ; Radical reactions ; Sulfur ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic free radicals of monovalent sulfur have not been hitherto observed in solution or in melts. Steric hindrance and resonance stabilization, which are responsible for the stability of the triarylmethyl, diphenylnitrogen, and phenoxyl radicals, are apparently insufficient to stabilize the organic free radicals of monovalent sulfur in such concentrations that they can be detected by current physical methods. - It was only in 1963 that aminopolysulfur radicals (R2N—Sn—S·) were detected in solution, and arylsulfur radicals (Ar-S·) and phenylselenium radicals were isolated at ca. -180°C. - Organically bound sulfur can be stabilized in the free-radical state if association of the radicals is prevented by fixing in a crystal lattice (“cystine radical”), by repulsion between radical ions (sulfinium salts), or by freezing-in (arylsulfur radicals).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196406021
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Proton Transfer, Acid-Base Catalysis, and Enzymatic Hydrolysis. Part I: ELEMENTARY PROCESSESPart II (Catalytic Mechanisms) will appear shortly in this journal.Dedicated to Dr. W. Foerst on the occasion of his 65th birthday (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 1-19 
    Details
    ISSN: 0570-0833
    Keywords: Proton transfer ; Catalysis ; Enzyme catalysis ; Hydrolysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The proton occupies a special position as a promoter and mediator in chemical reactions occurring in solution. Many reactions in organic chemistry are catalysed by acids or bases; likewise, most enzymes contain active groups which promote acid-base catalysis. To understand the reaction mechanisms involved, it is necessary to identify the elementary steps as well as their course in time. Systematic investigation of these elementary steps as well as their course in time. Systematic investigation of these elementary steps has become possible only with the development of new methods for studying very fast reactions. The present paper reviews the information obtained in this type of investigation. The result is a relatively complete picture of the elementary proton transfer mechanisms and a comprehensive description of the modes and laws of acid-base and enzymatic catalysis.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196400011
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  • 4
    Electronic Resource
    Electronic Resource
    The Mechanism of the Action of Organometallic CatalystsDedicated to Prof. Dr. Karl Winnacker on the occasion of his 60th birthday. (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 93-101 
    Details
    ISSN: 0570-0833
    Keywords: Organometallic catalysts ; Catalysis ; Reaction mechanisms ; Lithium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Kinetic investigations of the polyreaction of isoprene with organolithium compounds as initiators in n-heptane as solvent indicate the following sequence of reactions: 1. formation of an adduct between a monomeric form of the organolithium compound and the isoprene and 2. reaction of this adduct with an associated form of the organolithium compound with insertion of the isoprene. The adduct formation is considered to be due to chemisorption, and proof of such chemisorption of a monomer (ethylene) is also demonstrated for a homogeneous Ziegler-type catalyst. All the reactions can be formulated in the form of cyclic structures with electron-deficient character. Postulation of such ring structures explains the surprising values obtained for the frequency factors and equilibrium constants.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196400931
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  • 5
    Electronic Resource
    Electronic Resource
    Coordination Chemistry and Catalysis. Investigations on the Synthesis of Cyclooctatetraene by the Method of W. Reppe (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 185-191 
    Details
    ISSN: 0570-0833
    Keywords: Coordination modes ; Catalysis ; Cyclooctatetraenes ; Reppe chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relationship between the structure and the catalytic activity of nickel(II) complexes in the synthesis of cyclooctatetraene by the method of W. Reppe is discussed. The cyclotetramerization of acetylene takes place within labile Ni(II)-acetylene π-complexes. Inhibition tests have made it probable that four molecules of acetylene are grouped around the nickel ion in the transition state, in a configuration which favors the formation of the eight-membered ring.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196401851
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    Paper (German National Licenses)
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