Further spectroscopic and kinetic studies on carbonyloxyl radicals

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DOIResolve DOI: http://doi.org/10.1021/jo00007a029
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TypeArticle
Journal titleJournal of Organic Chemistry
ISSN0022-3263
Volume56
Issue7
Pages24052410; # of pages: 6
AbstractUV-visible absorption spectra and kinetic data obtained at room temperature are reported for three (alkenylcarbonyl)oxyls: trans-(CH 3) 3CCH=CHC(O)O •, 1a; trans-C 6H 5CH=CHC(O)O •, 1b; (CH 3) 2C=CHC(O)O •, 1c; and two (alkynylcarbonyl)oxyls: (CH 3) 3CC≡CC(O)O •, 2a; C 6H 5C≡CC(O)O •, 2b. Rate constants for decarboxylation of 1a, 1b, 2a, and 2b are estimated to be ≤1.1 × 10 7, 1 × 10 6, 5 × 10 5 and 2 × 10 5 s -1, respectively. The first-order decay of 1c would appear to occur primarily by an intramolecular H atom abstraction, k ∼ (2 ± 1) × 10 7 s -1. The (alkynylcarbonyl)oxyls are more reactive than the (alkenylcarbonyl)oxyls in a variety of H atom abstraction reactions, e.g., with c-C 6H 12, and addition reactions, e.g., with C 6H 5CH=CH 2. Combining the present and earlier 5-7 kinetic data for carbonyloxyls yields the following order of decreasing reactivity for hydrogen abstraction and addition reactions: RC≡CC(O)O • ≥ ROC(O)O • > RR′C=CHC(O)O • ≥ C 6H 5C(O)O •. The reactivities of meta- and para-substituted aroyloxyls can be correlated with the intrinsic acidities and with the pK a's of the corresponding benzoic acids, reactivity increasing with acid strength.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC)
Peer reviewedYes
NPARC number21276605
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Record identifier22cb3fff-b9e1-4d05-b638-bdc567ce5162
Record created2015-10-13
Record modified2016-05-09
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