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A comparative study on the degradation of cotton linters induced by carbonate and hydroxyl radicals generated from peroxynitrite.

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Title: A comparative study on the degradation of cotton linters induced by carbonate and hydroxyl radicals generated from peroxynitrite.
Authors: Magnus Carlsson, David Stenman, Gábor Merényi, Torbjörn Reitberger
Source: Holzforschung: International Journal of the Biology, Chemistry, Physics, & Technology of Wood. Feb2005, Vol. 59 Issue 2, p132-142. 11p.
Subjects: Linters, Chemical affinity, Atomic theory, Research methodology, Radicals (Chemistry)
Abstract: Carbonate (CO 3 •−) and hydroxyl (HO •) radicals were chemically produced in cotton linter suspensions using peroxynitrite as a radical precursor. Both radicals could degrade cotton linters, as shown by viscosity and GPC-SEC measurements. As evidenced by the viscosity measurements, the presence of oxygen during the cotton linter treatments slightly increased cellulose degradation by both radicals. For the carbonate radical, more than 90% of the viscosity losses could be recovered by reductive NaBH 4 treatment before measuring the viscosity, whereas only approximately 40% of the viscosity was recovered after hydroxyl radical degradation and subsequent NaBH 4 treatment. This indicates that carbonate radicals mainly abstract H-atoms adjacent to hydroxyl groups, i.e., at C 2, C 3 and C 6. This intramolecular selectivity may reflect a polar effect, whereby hydrogen atom abstractions from these positions are favoured. In addition, abstraction at C 6 would be sterically and statistically favoured. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Carbonate (CO 3 •−) and hydroxyl (HO •) radicals were chemically produced in cotton linter suspensions using peroxynitrite as a radical precursor. Both radicals could degrade cotton linters, as shown by viscosity and GPC-SEC measurements. As evidenced by the viscosity measurements, the presence of oxygen during the cotton linter treatments slightly increased cellulose degradation by both radicals. For the carbonate radical, more than 90% of the viscosity losses could be recovered by reductive NaBH 4 treatment before measuring the viscosity, whereas only approximately 40% of the viscosity was recovered after hydroxyl radical degradation and subsequent NaBH 4 treatment. This indicates that carbonate radicals mainly abstract H-atoms adjacent to hydroxyl groups, i.e., at C 2, C 3 and C 6. This intramolecular selectivity may reflect a polar effect, whereby hydrogen atom abstractions from these positions are favoured. In addition, abstraction at C 6 would be sterically and statistically favoured. [ABSTRACT FROM AUTHOR]
ISSN:00183830
DOI:10.1515/HF.2005.020