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ESR spin‐trap study of the radicals present during the thermolysis of some novel dialkyl peroxides
Author(s) -
Mekarbane Pierre G.,
Tabner Brian J.
Publication year - 2001
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/1097-458x(200101)39:1<9::aid-mrc776>3.0.co;2-3
Subject(s) - chemistry , radical , thermal decomposition , bond cleavage , medicinal chemistry , photochemistry , decomposition , adduct , methyl radical , organic chemistry , catalysis
The thermolysis of two bifunctional dialkyl peroxides [2,5‐dimethyl‐2,5‐bis( tert ‐butylperoxy)hexane ( 1 ) and 2,5‐dimethyl‐2,5‐bis( tert ‐butylperoxy)‐3‐hexyne ( 2 )] and two novel monofunctional dialkyl peroxides [2‐methyl‐(2‐ tert ‐amylperoxy)pentan‐4‐ol ( 3 ) and 2‐methyl‐(2‐ tert ‐butylperoxy)pentan‐4‐ol ( 4 )] was undertaken, in various solvents, between 353 and 383 K and the radicals generated trapped employing DMPO, PBN‐ d 14 and 2,4,6‐tri‐ tert ‐butylnitrosobenzene (TTBNB). We established that both 1 and 2 release the tert ‐butoxyl radical (and the methyl radical via β‐scission) following cleavage of one of the O—O bonds. During the thermolysis of 1 a · CH 2 R radical was trapped which we assign to the 3‐methyl‐3‐( tert ‐butylperoxy)butyl radical ( 6 ). We found no evidence for the presence of an alkynyl radical during the thermolysis of 2 . The tert ‐amyloxyl (and the ethyl radical via β‐scission) and the tert ‐butoxyl radical (and the methyl radical via β‐scission) were trapped during the thermolysis of 3 and 4 , respectively. The 2‐hydroxypropyl radical ( 10 ) was trapped employing TTBNB during the thermolysis of both 3 and 4 with its adduct exhibiting two magnetically non‐equivalent β‐protons as a consequence of the adjacent chiral carbon atom. Reaction schemes for the thermolysis all four peroxides are proposed based on the nature of the trapped radicals. Copyright © 2001 John Wiley & Sons, Ltd.