Identification and quantification of radical reaction intermediates by electron spin resonance spectrometry of laccase-catalyzed oxidation of wood fibers from beech ( Fagus sylvatica )

1997 ◽  
Vol 48 (4) ◽  
pp. 459-464 ◽  
Author(s):  
C. Felby ◽  
B. R. Nielsen ◽  
P. O. Olesen ◽  
L. H. Skibsted
Keyword(s):  
Electron Spin Resonance ◽  
Fagus Sylvatica ◽  
Electron Spin ◽  
Radical Reaction ◽  
Reaction Intermediates ◽  
Wood Fibers ◽  
Spin Resonance ◽  
Catalyzed Oxidation ◽  
Identification And Quantification

Nitroxides as reaction intermediates

1982 ◽  
Vol 60 (12) ◽  
pp. 1414-1420 ◽  
Author(s):  
Hans Gunter Aurich
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Isopropyl Alcohol ◽  
High Reactivity ◽  
Reaction Intermediates ◽  
Reaction Products ◽  
Nitronyl Nitroxide ◽  
Reaction Conditions ◽  
Spin Resonance ◽  
Secondary Reactions

Vinyl nitroxides 4 are obtained by oxidation of the nitrones 3, as was shown by esr studies and by identification of the reaction products. The formation of 4d–f is even observed in oxidation of the hydroxylamines 1d–f, nitroxides 2d–f and nitrones 3d–f being the intermediates. The high reactivity of the vinyl nitroxides 4 at their β-position is illustrated by the reactions of 4a with various compounds affording the nitroxides 7–10, respectively. Compound 4c reacts with its precursor 3c to give 11, 12, or 13, depending on the reaction conditions. From oxidation of 3a, c, and e the dimerization products 5a, c, and e, respectively, could be isolated. Whereas further oxidation of 5d yields 6d, the acyl nitroxides 14a and c are formed in the oxidation of 5a and c, respectively.The formation of quinone 23 in the reaction of 2-methyl-2-nitrosopropane with potassium tert-butoxide in isopropyl alcohol in the presence of oxygen is discussed. The nitroxide 20 has been detected in the reaction mixture. Imines 24 react with nitrosobenzene giving nitroxides 26. These are further oxidized by nitrosobenzene to afford nitrones 27. Whereas 27a and b could be isolated, 27c and d undergo further reaction yielding the diimines 30c and d along with dinitrone 29.The formation and reactions of imino nitroxides 31 and of the nitronyl nitroxide 41 are discussed. Electron spin resonance studies revealed the high reactivity of the imidazolyl-1,3-dioxides 46 and the imidazolyl-1-oxides 50, which easily form radicals 47–49 and 51, respectively, which are derived from secondary reactions.

Temperature Dependence of Copper (II) Catalyzed Oxidation of Propylene on X Zeolite: Relation To Copper (II) Migration

1987 ◽  
Vol 111 ◽  
Author(s):  
Jong-Sung Yu ◽  
Larry Kevan
Keyword(s):  
Activation Energy ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Flow System ◽  
Substantial Part ◽  
Zeolite Lattice ◽  
Spin Resonance ◽  
X Zeolite ◽  
Catalyzed Oxidation ◽  
Total Activation

AbstractThe copper(II) catalyzed oxidation of propylene on CuK-X zeolite was studied over the temperature range of 150 to 400°C in a flow system. Arrhenius activation energies could be obtained at less than 30%conversion from 160 to 210°C and were found to decrease with increasing copper(II) content. These results are correlated with electron spin resonance studies of the migration of copper(II) within the zeolite lattice at the reaction temperature. The change in activation energy with copper(II) content shows that a substantial part of the total activation energy is due to copper(II) migration.

ELECTRON SPIN RESONANCE STUDIES OF THE RADIATION-INDUCED ADDITION OF HBr TO C2H4 IN THE SOLID STATE

1960 ◽  
Vol 38 (5) ◽  
pp. 689-696 ◽  
Author(s):  
F. W. Mitchell ◽  
B. C. Green ◽  
J. W. T. Spinks
Keyword(s):  
Electron Spin Resonance ◽  
Reaction Mechanism ◽  
Solid State ◽  
Liquid Nitrogen ◽  
Electron Spin ◽  
Reaction Intermediates ◽  
Γ Irradiation ◽  
Solid Mixture ◽  
Spin Resonance ◽  
Radiation Induced

Electron spin resonance measurements at 77 °K have been used to study the hydrobromination of ethylene induced by γ irradiation of the solid mixture at liquid nitrogen temperatures. The evidence resulting from these studies has given valuable information regarding the reaction intermediates and has been used in formulating a likely reaction mechanism.

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