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'Radical Reactions' in keywords Facet   Publication Year 1983  [X]
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1Author    Mohamed Al-Sheikhly, Clemens Von SonntagRequires cookie*
 Abstract    The y-radiolysis of N20-saturated aqueous solutions generates OH radicals and a small amount of H atoms. In 1,3-dimethyluracil solutions (10 -3 M) these radicals add mainly to the 5-position of the C(5) -C(6) double bond of the solute. The resulting products have been identified by GC-MS after trimethylsilylation. The major products (G values in brackets) are dimers of the C(5)-OH-adduct radicals (3.4), 5,6-dihydro-5,6-dihydroxy-1,3-dimethyl-uracil (0.85), 5,6-dihydro-5-hydroxy-1,3-dimethyluracil (0.75), dimer of the C(5)-0H-adduct with the C(5)-H-adduct radical (0.2) and 5,6-dihydro-6-hydroxy-l,3-dimethyl-uracil (0.2). G(1,3-dimethyluracil consumption) has been found to be 5.7. The major reaction in this system is the dimerisation of the primary radicals. To a small extent the primary radicals also disproportionate by electron transfer to give the glycol 5,6-dihydro-5,6-dihydroxy-l,3-dimethyluracil as one of the products. Radiolytically formed H202 which could oxidise the C(5)-0H-adduct radical does not contribute to the formation of the glycol because the H202 yield is not reduced with respect to its expected "molecular yield" (G = 0.75). In contrast to the uracil system where it has been reported that drastic changes in radiolytic yields occur on going from neutral to alkaline irradiation conditions no such changes have been observed with 1,3-dimethyluracil. However, an acid-catalysed rearrangement from the C(5)-OH-adduct to the C(6)-0H-adduct radical is observed in the present system. 
  Reference    Z. Naturforsch. 38b, 1622—1629 (1983); received June 27 1983 
  Published    1983 
  Keywords    Hydroxyl Radicals, Electron Transfer Reactions, Radical Reactions, DNA Model Systems 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-1622.pdf 
 Identifier    ZNB-1983-38b-1622 
 Volume    38 
2Author    J. Cadet, L. Voituriez, M. Berger, L. S. MyersRequires cookie*
 Title    Radiation-Induced Degradation of Purine and Pyrimidine 2'-Deoxyribonucleosides in Aqueous KBr Solutions  
 Abstract    Steady-state y-radiolysis of 5 x 10 -4 M pyrimidine and purine 2'-deoxyribonucleosides in aqueous solutions saturated with N2, N2O and O2, respectively, have been carried out in the presence of 0.1 M KBr. The main final degradation products have been isolated and characterised by various spectroscopic measurements including !H and 13 C NMR, UV, C.D. and mass spectrometry. The radiation-induced decomposition of thymidine is mostly accounted for by an ionic mechanism involving Br2, the decay product of Br2 --, as the reactive oxidising specie. On the other hand the degradation of the purine ring of 2'-deoxy-adenosine and 2'-deoxyguanosine may be accounted for by the action of Br2 --or Br3-2_ . 
  Reference    Z. Naturforsch. 38b, 1643—1651 (1983); received August 4/July 28 1983 
  Published    1983 
  Keywords    2'-Deoxyribonucleosides, Inorganic Radical, y-Irradiation, Radical Reactions, Thymidine Oxidation 
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 TEI-XML for    default:Reihe_B/38/ZNB-1983-38b-1643.pdf 
 Identifier    ZNB-1983-38b-1643 
 Volume    38