Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Ein sterisch gehindertes Brückenkopfsystem: 13-Substituierte 1,4,5,8,9,12-Hexamethyltriptycene (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2147-2151 
    Details
    ISSN: 0009-2940
    Keywords: Bridgehead reactivity ; Front strain ; Isonitrile-nitrile rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Sterically Hindered Bridgehead System: 13-Substituted 1,4,5,8,9,12-HexamethyltriptycenesThe synthetic access to five 13-X-substituted 1,4,5,8,9,12-hexamethyltriptycenes (X = NO2, NC, CN, NH2, NHCHO) is described. Due to steric hindrance of the bridgehead position by the methyl groups in position 1, 8 and 9 it was impossible neither to formylate nor acetylate the 13-amino compound 23, nor to dehydrate the 13-formamido compound 22 to the isocyanide 19 by standard methods.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Sterische Behinderung der Isocyanid-Cyanid-Umlagerung in einer Brückenkopfposition (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 971-972 
    Details
    ISSN: 0009-2940
    Keywords: Isocyanide-cyanide rearrangement ; Bridgehead reactivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steric Hindrance of the Isocyanide-Cyanide Rearrangement in a Bridgehead PositionThe activation barrier of the isocyanide-cyanide rearrangement of 13-isocyano-1,4,5,8,9,12-hexamethyltriptycene (5) is the highest of all known isocyanides. The special position of this compound can be explained by a strong increase of strain enthalpy during the isomerization. This is due to the cage-like inclusion of the isocyano group in the bridgehead position by the methyl groups in the positions 1, 8, and 9.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240443
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    New Hydrogen Transfer Catalysts (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2219-2230 
    Details
    ISSN: 1434-193X
    Keywords: Retrodisproportionation ; Arenes ; EPR spectroscopy ; Thermochemistry ; Coal liquefaction ; Catalysis ; Hydrogen transfer ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transfer of hydrogen from excess 9,10-dihydroanthracene (DHA) to acceptors such as α-methylstyrene is catalyzed, i.e. occurs at temperatures in the range 200-260 °C instead of 280-320 °C, when hydrocarbons with weaker C-H bonds than DHA, e.g. 6H-benzo[cd]pyrene (4), 7H-dibenzo[a,kl]anthracene (5), 4-methyl-7H-benzo[de]naphthacene (6) or 8H-dibenzo[b,fg]pyrene (7), are added to the reaction mixture. The reactions are initiated by bimolecular H-atom transfer from 4-7 to the acceptor (retrodisproportionation) and proceed by nonchain radical mechanisms. This is supported by isotopic labelling and kinetic isotope effects, substituent and solvent effects, EPR spectroscopy of intermediate radicals, and by a comparison of the thermochemical and kinetic characteristics of these reactions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Uncatalyzed Transfer Hydrogenation and Transfer Hydrogenolysis: Two Novel Types of Hydrogen-Transfer ReactionsDedicated to Professor Paul D. Bartlett on the occasion of his 90th birthday (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 36 (1997), S. 1406-1430 
    Details
    ISSN: 0570-0833
    Keywords: arenes ; coal liquefaction ; hydrogenations ; radical reactions ; reaction mechanisms ; Arenes ; Coal liquefaction ; Hydrogenation ; Radical reactions ; Reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Uncatalyzed transfer hydrogenations are H2-transfer reactions in which donors that contain weakly bound hydrogen atoms undergo an H-atom transfer (retrodisproportionation) onto an acceptor containing unsaturated bonds such as C=C, C=O, C=N, N=N, N=O. Transfer hydrogenolyses are reactions in which σ bonds are cleaved upon additon of H2. These hydrogenations are terminated by H, transfer; they do not follow a radical-chain mechanism. The initial steps of both types of reactions, H-atom transfer, complement the bimolecular formation of 1,4-diradicals from alkenes or heteroalkenes within the scope of bimolecular radical formation (Molecule-Induced Radical Formation, MIRF). The title reactions play an important role in coal liquefaction, aromatization reactions with nitroarenes or quinones, and possibly biochemical dehydrogenations. This review focuses on mechanistic studies, structure-reactivity relationships, and current applications of these reactions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199714061
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...