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ESR study of reactions of cellulose with ·OH generated by Fe +2 /H 2 O 2
Author(s) -
Arthur Jett C.,
Hinojosa Oscar,
Bains M. S.
Publication year - 1968
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1968.070120613
Subject(s) - radical , cellulose , acrylonitrile , chemistry , electron paramagnetic resonance , microcrystalline cellulose , photochemistry , singlet state , molecule , polymerization , polymer chemistry , excited state , organic chemistry , polymer , nuclear magnetic resonance , physics , nuclear physics , copolymer
It was demonstrated by ESR spectroscopy that the Fe +2 /H 2 O 2 system gave a reactive species which generated an ESR triplet spectrum or sorbitol similar to that generated by hydroxyl radicals from the Ti +3 /H 3 O 2 system. An ESR spectrum was obtained for the hydroxyl radicals generated by the latter system. However, the lifetime of hydroxyl radicals, generated by the Fe +2 /H 2 O 2 system, was apparently very short, and an ESR spectrum for the hydroxyl radicals, generated by this system, was not observed. The Fe +2 /H 2 O 2 system also generated triplet spectra with cotton cellulose I, cotton cellulose II, and microcrystalline cellulose, suggesting that a hydrogen atom had been abstracted from the hydroxyl group on carbon C 6 , or possibly the hydrogen atom on carbon C 5 . The ESR spectrum generated on microcrystalline cellulose was less intense than those generated on cellulose I and II. On initiation of graft polymerization of the activated cellulose with acrylonitrile, the triplet spectrum disappeared and was replaced by two strong singlet spectra. One of the singlet spectra was likely generated on carbon C 1 or C 4 on depolymerization of the cellulose molecule, and the other was probably generated on the end of the growing polyacrylonitrile molecular chain. The absence of a triplet spectrum gave direct evidence for the order in which the acrylonitrile monomer was being grafted onto the cellulose molecule. The mechanisms proposed by Haber and Weiss for the reactions generated in the Fe +2 /H 2 O 2 system were generally supported.