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'Semiquinones' in keywords Facet   section ZfN Section C  [X]
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1985 (2)
1Author    HartmutB. Stegmann, Hoang Dao-Ba, Klaus Scheffler, MartinG. PeterRequires cookie*
 Title    ESR and ENDOR Investigations of Adrenochrome Semiquinone and Related Amino-1,2-Benzosemiquinone Radicals  
 Abstract    Dimethyl or diethylamine reacts very smoothly in ethanol solution with catechols to the corre­ sponding aminoquinones. The paramagnetic intermediates, the semiquinones, are investigated by ESR and E N D O R spectroscopy using the spin stabilisation technique with diarylthallium cations. The spectra of these radicals show clearly the thallium and nitrogen coupling and the hydrogen hyperfine structure. For some examples the signs of the proton coupling constants are determined by T RIPLE resonance experiments. The results indicate a negative spin density in one position of the unsymmetrically substituted radical 3. With the results obtained for the monocyclic aminosemiquinones the hyperfine structure of the adrenochrome semiquinone is analysed. 
  Reference    Z. Naturforsch. 40c, 531 (1985); received January 31/March 27 1985 
  Published    1985 
  Keywords    ESR-, ENDOR-Spectroscopy, Semiquinones, Adrenochrome 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0531.pdf 
 Identifier    ZNC-1985-40c-0531 
 Volume    40 
2Author    MartinG. Peter, HartmutB. Stegmann, Hoang Dao-Ba, Klaus SchefflerRequires cookie*
 Abstract    ESR-spectra were recorded during the oxidation of N-acetyldopamine and N-ß-alanyldopamine in aqueous solutions. Semiquinone radicals were detected under conditions of spin stabilization by Z n2+ ions. The appearance of the spectra was the same in the presence or in the absence of proteins. No evidence was obtained for the formation of products that could have arisen eventual­ ly from intermolecular Michael-type addition of nitrogen nucleophiles. 
  Reference    Z. Naturforsch. 40c, 535—538 (1985); received January 31 1985 
  Published    1985 
  Keywords    ESR-Spectroscopy, Catecholamines, Semiquinones, Insect Cuticle 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0535.pdf 
 Identifier    ZNC-1985-40c-0535 
 Volume    40