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The role of triplet repulsion in elementary steps of cyclic chain termination of oxidizing polymers and other substances
Author(s) -
Denisov Evguenii T.
Publication year - 1997
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19971150105
Subject(s) - oxidizing agent , radical , chemistry , activation energy , photochemistry , chain termination , polymer , chain (unit) , polymer chemistry , organic chemistry , physics , polymerization , astronomy , radical polymerization
Parabolic model of the transition state was used for analysis of activation energies of reduction of benzoquinone (Q), aminyl (Am * ), and nitroxyl (AmO * ) radicals by peroxyl radicals of different structure. It was proved that radicals HO 2 * and R 2 C(OH)O 2 * reduce Am * , and AmO * with zero activation energy due to low triplet repulsion in the transition state. On the contrary alkylperoxyl radicals reduce Am * and AmO * slowly due to high triplet repulsion and sufficiently high activation energy. That is why AmH and AmOH perform cyclic chain termination in oxidizing substances where peroxyls with OH‐group are generated.