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  • Acetylacetone, hexafluoro-  (1)
  • Coordination modes  (1)
  • Cyclizations  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 315-320 
    ISSN: 0009-2940
    Keywords: Acetylacetone, hexafluoro- ; Diol formation / Enolization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Eine spektroskopische und mechanistische Untersuchung der Enolisierung und Diol-Bildung von Hexafluoracetylaceton in Gegenwart von Wasser und AlkoholDie Reaktionen von Hexafluoracetylaceton (Hfac) (6) mit Wasser, Methanol, Ethanol und Isopropylalkohol wurde im einzelnen anhand von 1H-, 13C-, 17O-, 19F-NMR- und UV-VIS-Spektroskopie untersucht. Dabei konnten die Zwischen- und Reaktionsprodukte bei der Enolisierung und Diol-Bildung spektroskopisch identifiziert werden. Die vorgeschlagenen Reaktionswege werden unter Bezug auf früher in der Literatur berichtete Daten diskutiert. Ein wichtiges Ergebnis dieser Untersuchung ist der direkte Nachweis für die Bildung der Addukt-Spezies Hfac(OH)4 (10), Hfac(OMe)2 (13a) und Hfac(OEt)2 (13b).
    Notes: The reactions of hexafluoroacetylacetone (hfac) (6) with water, methanol, ethanol, and isopropyl alcohol were studied in detail using 1H-, 13C-, 17O-, 19F-NMR, und UV-VIS spectroscopy. The reported spectra enable the identification of intermediate and product species, and allow a mechanistic analysis of the enolization and diol formation. The suggested mechanisms are discussed with reference to earlier data reported in the literature. An important feature of this study is the direct evidence presented for the formation of the adduct species hfac(OH)4 (10), hfac(OMe)2 (13a), and hfac(OEt)2 (13b).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-193X
    Keywords: Cyclizations ; Electron transfer ; High-pressure effects ; Radical cations ; Silyl enol ethers ; Solvent effects ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidative photoinduced electron transfer (PET) reactions have been performed with various silyl enol ethers and silyloxy-2H-chromones bearing an olefinic or silylacetylenic side chain. The reactions result in regioselective ring closure with the formation of bi- to tetracyclic ring systems with a well-defined ring juncture, e.g. perhydrophenanthrenones 13 or benzo-annellated xanthenones 24. Our investigations have focussed on the optimization of this cyclization method with regard to irradiation time and product yield. The irradiation times could be reduced by using the cosensitized PET method. Modifying the substrate at the silyl group led to enhanced yields. In addition, we found that solvent and pressure dependences are important tools, allowing control of the regiochemistry. Both the synthesis of 6-endo products by radical cationic reaction pathways, as well as 5-exo ring closure by radical intermediates was achieved. Mechanistic details, including findings from deuterium labelling experiments, are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 25 (1986), S. 673-682 
    ISSN: 0570-0833
    Keywords: Reaction dynamics ; Coordination modes ; High-pressure chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to understand the dynamics of chemical reactions in general, detailed information on electronic, structural and kinetic properties is required. The key questions on how chemical reactions actually occur can in many cases only be answered in terms of information obtained from kinetic studies. In conventional kinetic studies of chemical reactions in solution, the variables usually selected include concentration, acidity, solvent, and temperature. In recent years, pressure has become an additional selected variable in such studies. It enables the measurement of the volume of activation and the construction of reaction volume profiles and thus assists in the elucidation of the underlying mechanism; it also completes the comprehension of reaction kinetics by adding another kinetic parameter that the suggested reaction mechanism must account for. Furthermore, the volume of activation is the only transition state property that can be correlated with the corresponding ground state property in an experimentally simple manner. In this paper, the insights so gained in our understanding of the dynamics of reactions involving coordination complexes will be presented. Such reactions are of fundamental interest to chemists since they often form the basis of catalytic, biological, environmental and energy related processes. Any additional information that will add to the understanding of the reaction dynamics is therefore of exceptional importance.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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