Oxide Radical Anion Reactivity with Aliphatic Amino Compounds in Aqueous Solution:  Comparison of H−Atom Abstraction from C−H and N−H Groups by•O-and•OH Radicals

2004 ◽  
Vol 108 (12) ◽  
pp. 2238-2246 ◽  
Author(s):  
David A. Armstrong ◽  
Klaus-Dieter Asmus ◽  
Marija Bonifačic
Keyword(s):  
Aqueous Solution ◽  
Radical Anion ◽  
Oh Radicals ◽  
Amino Compounds

Pulsradiolytische Untersuchung zur Oxidation der Ascorbinsäure durch OH-Radikale und Halogen-Radikal-Komplexe in wäßriger Lösung / Pulse Radiolysis Studies of the Oxidation of Ascorbic Acid by OH-radicals and Halide Radical Anion Complexes in Aqueous Solution

1972 ◽  
Vol 27 (6) ◽  
pp. 649-659 ◽  
Author(s):  
M. Schöneshöfer
Keyword(s):  
Aqueous Solution ◽  
Ascorbic Acid ◽  
Radical Anion ◽  
Oh Radicals ◽  
Oh Radical ◽  
Extinction Coefficients ◽  
Acid Radical ◽  
Tautomeric Forms ◽  
Anion Complexes ◽  
Millisecond Range

Ascorbic acid is oxidized by the OH radical and by radical anion complexes X2⁻ (X: Cl, Br, J, SCN) to yield the “ascorbic acid radical”which finally disappears by second order. The pK of this radical was found to be about 3. It has several precursor radicals formed by the addition of OH or X to ascorbic acid. They lose H2O or HX, respectively, with different rates or are desactivated in radical-radical reactions. The precursor radicals are acids of different pK values. Since ascorbic acid exists in two tautomeric forms in aqueous solution, two precursor radicals are postulated for the reaction of OH with ascorbic acid:They lose water or OH⁻ with different rates to form the ascorbic acid radical. The absorption spectra of these species were measured. All radicals including the ascorbic acid radical have strong absorption at 3600 A, although somewhat different extinction coefficients. The decay of the 3600 A absorption in the 100 μs and millisecond range, which in earlier work of BIELSKI et al. 3 has been attributed solely to the disappearance of the ascorbic acid radical is partly due to the loss of water of long-lived precursors and to radical-radical desactivation of precursors and the ascorbic acid radical. Earlier conclusions of BIELSKI et al. about the pK of the ascorbic acid radical and about its protonization cannot be confirmed taking into consideration the complex precursor reactions. The kinetics is strongly dependent on the dose below about 400 rad. The precursor radicals formed by the addition of X to ascorbic acid are generally shorter lived than the OH addition precursors.

Oxidative etching of MoS2/WS2 nanosheets to their QDs by facile UV irradiation

2016 ◽  
Vol 18 (45) ◽  
pp. 31211-31216 ◽  
Author(s):  
Xiaolong Lu ◽  
Rongguo Wang ◽  
Lifeng Hao ◽  
Fan Yang ◽  
Weicheng Jiao ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Uv Irradiation ◽  
Oh Radicals ◽  
Oxidative Etching ◽  
Ws2 Nanosheets

˙OH radicals produced under UV irradiation in aqueous solution induce the oxidative etching of MoS2/WS2 nanosheets to QDs.

γ-Radiolyses of DNA in Oxygenated Aqueous Solution. Structure of an Alkali-Labile Site

1977 ◽  
Vol 32 (11-12) ◽  
pp. 1021-1022 ◽  
Author(s):  
Miral Dizdaroglu ◽  
Dietrich Schulte-Frohlinde ◽  
Clemens von Sonntag
Keyword(s):  
Aqueous Solution ◽  
Solution Structure ◽  
Oh Radicals ◽  
Phosphatase Treatment ◽  
Alkali Labile Site

Abstract Erythritol-1-d1 has been isolated from γ-irradiated aqueous oxygenated solution of DNA after reduction with NaBD4 , alkali and phosphatase treatment. It is concluded that this product stems from a ᴅ-erythrose 2,4-diphosphate unit in the DNA which is formed via a sequence of reactions following H-abstraction at C-2′ by OH radicals..

Site of H Atom Attack on Uracil and Its Derivatives in Aqueous Solution

1985 ◽  
Vol 40 (3-4) ◽  
pp. 292-294 ◽  
Author(s):  
Suresh Das ◽  
David J. Deeble ◽  
Clemens von Sonntag
Keyword(s):  
Aqueous Solution ◽  
Double Bond ◽  
Pulse Radiolysis ◽  
Hydrogen Abstraction ◽  
Methyl Groups ◽  
Oh Radicals ◽  
Hydrogen Atoms ◽  
Sugar Moiety ◽  
Reducing Properties

Hydrogen atoms from the radiolysis of water at pH 1.6 add to the 5,6-double bond of pyrimidines. The preferen­tial site of attack is the C(5) position (values in brackets) in the case of 6-methyluracil (87%), 1,3-dimethyluracil (71%), uracil (69%) and poly(U) (60%). This reaction yields a radical of reducing properties which can be monitored by its reaction with tetranitromethane in a pulse radiolysis experiment. In thymine (37%), thymidine (32%) and 1,3-dimethylthymine (25%) H-addition no longer pre­ferentially occurs at C(5), but addition is now mainly at C(6). Hydrogen abstraction from the methyl groups or the sugar moiety is negligible (≦ 5.5%). A comparison is made with literature values for the equivalent reactions of OH radicals.

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