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'Radicals' in keywords Facet   Publication Year 1980  [X]
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1Author    Norio Miyoshi, Giiti TomitaRequires cookie*
 Title    Fluorescein-photosensitized Furan Oxidation in Methanolic and Reversed Micellar Solutions, Part II Kinetic Analysis  
 Abstract    The 1,3-diphenylisobenzofuran oxidation was investigated in methanolic and dodecyl-ammonium propionate reversed micellar solutions using fluorescein sodium as photo-sensitizer. The furan oxidation was caused by the singlet oxygen mechanism (Type II). Aniline enhanced remarkably the furan oxidation in methanolic solutions, but inhibited highly this oxidation in the reversed micellar solutions. This enhancement of the furan oxidation was considered to be brought about by the occurrence of a radical mechanism (Type I) besides Type II mechanism. No Type I reaction occurred in the micellar solutions. The rate constants concerning with both reaction processes were evaluated by kinetic analysis, employing various aryl-and alkyl-amines. The reaction mechanism of Type I and the quenching mechanism of singlet oxygen by amines were discussed from the relationship between the rate constants, and the ionization potential of amines and the solvent polarity. 
  Reference    (Z. Naturforsch. 35b, 107—111 [1980]; received July 27 1979) 
  Published    1980 
  Keywords    Singlet Oxygen, Radicals, Fluorescein, Diphenylisobenzofuran, Reversed Micelles 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0107.pdf 
 Identifier    ZNB-1980-35b-0107 
 Volume    35 
2Author    Wolfgang Flossmann, Herbert Zehner, Adolf MüllerRequires cookie*
 Title    Radicals Produced in Single Crystals of Thymine Derivatives by UV and X-Rays  
 Abstract    Single crystals o f anhydrous thym ine (T), thym ine monohydrate (T ■ H 20) , 5,6-dihydrothym ine (T H 2), 1-methylthymine (mT) and thym idine (dT) were irradiated with X-rays and UV between 77 K and 300 K. Six types o f radicals were analyzed by ESR-spectroscopy at 9.5 G H z and 35 G H z after exposure to X-rays. The anion radical occurred only in T • H 20 at 77 K, the 4-yl radical only in T H 2 at 77 K and the 1-yl radical only in T between 77 K and 300 K. The 6 -yl radical was found in T, T H 2 and mT. It was converted into the 5-yl radical irreversibly by heat or white light (A < 600 nm). The 5-yl radical appeared in all compounds at room temperature. The highest thermal stability was found for the 7-yl radical which was present at room temperature in all compounds except T H 2 . U V -irradiation (A = 320 nm) produced radicals only in three crystals (T, T H 2 , dT). In T the 5-yl radical was found after exposure at 300 K, and two other radicals, 1-yl and 7-yl, at 77 K. A lso at 77 K, the 7-yl radical was present in dT and the 5-yl radical in TH 2 and dT. 
  Reference    Z. Naturforsch. 35c, 20—2 (1980); received July 23 1979 
  Published    1980 
  Keywords    Radicals, Single Crystals, Thym ine, X-Rays, ESR 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0020.pdf 
 Identifier    ZNC-1980-35c-0020 
 Volume    35