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  • 1980-1984  (2)
  • 2-Alkylidene-1,3-indandiones  (1)
  • Autoxidation  (1)
  • Chemistry  (1)
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  • 1
    ISSN: 1434-4475
    Keywords: 2-Alkylidene-1,3-indandiones ; Autoxidation ; 1-Hydroxy-2-vinylinden-3-ones ; Photoenolisation ; 2-Vinyl-1,3-indandion-2-yl radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The title compound,1, slowly decomposes in solution by autodixation, especially in daylight. The chemism of this photoinduced autoxidation has been investigated. Upon irradiation1 passes to the brick red isolable dienol2. The quantum yield is 0.3 at 313 nm in methanol. In solution an equilibrium is set up within several minutes between2 and the colorless deconjugated3. Unpolar or moderately polar solvents shift the equilibrium completely to3, whereas in highly polar solvents2 and3 coexist. In the dark the equilibrium1⇄2 (ca. 50∶1 in methanol) is established very slowly.3 upon irradiation reacts further to dimer8. 2 instantaneously reacts with oxygen. With high oxygen concentrations, hydroperoxide9 is formed, with lower ones dehydrodimer10, inter alia.9 and10 may further form12, 14, and15. These reactions, together with ESR spectroscopy, point to a central role of the free radical13 both in the autoxidation and in the reaction10→14. Basic catalysis sets up an equilibrium between1 and its dimer,17. The photoreaction1→2 has been investigated by sensitizing and quenching experiments.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 586-597 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isolation and Energy Well of the 2,3-Dimethylene-1,4-cyclohexadiyl DiradicalIrradiation of both 5,6-dimethylene-2,3-diazabicyclo[2.2.2]oct-2-ene (1) and 2,3-dimethylene-bicyclo[2.2.1]octan-7-one (2) matrix isolated in argon yields the 2,3-dimethylene-1,4-cyclohexadiyl diradical (8), which was characterized by its UV and IR spectra. From the decomposition rate of 1, the dimerisation rate of 8, determined by flash photolysis of 1, and the product ratio of the monomeric and dimeric products obtained from 8, the energy well of 8 has been determined to be 23.8 kcal mol-1.
    Notes: Die Bestrahlung von 5,6-Dimethylen-2,3-diazabicyclo[2.2.2]oct-2-en (1) sowie 2,3-Dimethylen-bicyclo[2.2.1]octan-7-on (2) in einer Argon-Matrix liefert das 2,3-Dimethylen-1,4-cyclohexadiyl-Diradikal (8), das durch sein UV- sowie sein IR-Spektrum charakterisiert wurde. Aus der Zerfallsgeschwindigkeit von 1, der durch Blitzlichtphotolyse von 1 ermittelten Dimerisierungs-geschwindigkeit von 8 und dem Verhältnis der sich von 8 ableitenden monomeren und dimeren Produkte wird für 8 eine Energiemulde von 23.8 kcal mol-1 bestimmt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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