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  • 1
    Electronic Resource
    Electronic Resource
    On the Thermal Cycloisomerization of 1-Vinylnaphthalene to acenaphthene. A mechanistic D-labeling study (1994)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 415-420 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Unlabeled 1-vinylnaphthalene (1) as well as positionally D-labeled 1 have been prepared and subjected to gas phase pyrolysis at low partial pressures of the educt compounds in nitrogen. At 700°C, 1 rearranges exclusively to acenaphthene (2). Under the conditions applied a significant H-D-exchange in the 1-vinylnaphthalene as well as in the formed acenaphthene takes place. The results obtained in this way and those resulting from pyrolysis in hydrogen (instead of nitrogen) show that despite the very high degree of dilution the high selectivity of cycloisomerization from 1 to 2 is firstly controlled by H-atom driven radical chain processes, in which the cyclization of the 2-naphthylethylradical dominates the reaction course.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19943360506
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  • 2
    Electronic Resource
    Electronic Resource
    Oxidative Cyclisierung von Anilinopyrazolen zu Pyrazolo[1,5-a]benzimidazolenHerrn Professor Christoph Rüchardt zum 65. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1729-1733 
    Details
    ISSN: 0009-2940
    Keywords: Pyrazoles ; Aminyls, heterocyclic ; Pyrazolo[1,5-a]benzimidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free Radical Reactions of N-Heterocyclic Compounds, XIV[1]. - Oxidative Cyclization of Anilinopyrazoles to Pyrazolo[1,5-a]benzimidazolesHerrn Professor Christoph Rüchardt zum 65. Geburtstag gewidmet.Substituted Anilinopyrazoles 1 were oxidized by dibenzoyl peroxide or lead(IV) oxide. Different oxidation products were isolated depending on the substituents in the anilino group of anilinopyrazoles 1. Intermediate pyrazolyl radicals 5, which could be trapped by triphenylmethyl or phenoxyl radicals, undergo cyclization reaction with formation of pyrazolo[1,5-a]benzimidazoles 4. The structures of compounds 4 were proven by 1H- and 13C-NMR spectroscopy, 15N labeling and transformation of 4e to the betain 7e.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270924
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  • 3
    Electronic Resource
    Electronic Resource
    Das Thermogramm einer C6H6-Chemie im Temperaturbereich von 450 bis 730°C (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1747-1753 
    Details
    ISSN: 0009-2940
    Keywords: Isomerization, thermal ; Radicals ; D-Labeling ; 1,5-Hexadiyne ; Pentafulvene ; Rearrangement, homoallyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal Rearrangements, XXIII[1].  -  The Thermogram of a C6H6 Chemistry in the Temperature Range from 450 to 730°CThe thermal isomerization of 1,5-hexadiyne (1) and its [1,6-D2]-labeled derivative (1a) was studied in the temperature range 450-730°C and in the presence of different carrier gases (N2, H2, D2, N2/toluene). By detailed analysis (GC, GC MS, NMR) all volatile reaction products were identified and determined quantitatively by using hexafluorobenzene as an internal standard. The experimental data show clearly that the reaction products are formed by two different routes: (i) electrocyclization leading to dimethylene cyclobutene (3) at temperatures up to about 600°C and (ii) radical reaction leading to benzene (4) and pentafulvene (5) at temperatures above 550°C. Cyclopentadienylmethyl radicals are supposed to be the essential radical intermediates.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270926
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    Paper (German National Licenses)
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