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Original scientific paper

On Formation of Anthrasemiquinone in the Conditions of Wood Alkaline Pulping

Sergey M. Shevchenko ; »Rudjer Bošković" Institute, 41000 Zagreb, Yugoslavia
Valentin E. Zubarev ; Moscow University, Moscow, USSR
Andrey P. Rudenko ; Leningrad Forest Technical Academy, 194018 Leningrad, USSR

Full text: english pdf 4.689 Kb

page 763-773

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Electron spin resonance (ESR) and electronic absorbance
spectral experiments demonstrate that reversible temperature
variation of anion-radica1 concentration in the system anthraqui;
none (AQ) - anthrasemiquinone (AS) - anthrahydroquinone
(AHQ) in aqueous alka1i is a property of that system and not of
the more complicated catalyst-wood system. Lignin model compounds
present in low concentrations have no influence on this variation. A raise of radical concentration is accompanied by a change of the solution colour from red into yellow. In pulping conditions AQ can be reduced either by the hydrocarbon or by the lignin component of wood, probably also by numerous organic compounds and even by the alka1i itself. As a result of this process, an AQ-AS-AHQ system is being formed.


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