Laser flash photolysis studies on the first superoxide thermal source. First direct measurements of the rates of solvent-assisted 1,2-hydrogen atom shifts and a proposed new mechanism for this unusual rearrangement

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DOIResolve DOI: http://doi.org/10.1021/ja993570b
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TypeArticle
Journal titleJournal of the American Chemical Society
ISSN0002-7863
Volume122
Issue31
Pages75187527; # of pages: 10
Subjectalcohol derivative; anion; benzyl derivative; cation; deuterium oxide; hydrogen; ketene derivative; nitrite; radical; solvent; superoxide; article; chemical reaction kinetics; decomposition; laser; oxidative stress; photolysis; reaction analysis; thermal analysis
AbstractThe thermal decomposition of bis(4-carboxybenzyl)hyponitrite (SOTS-1) in aerated water under physiological conditions has previously been shown to give the superoxide radical anion in a yield of 40 mol % (Ingold, K. U.; et al. J. Am. Chem. Soc. 1997, 119, 12364). The absolute kinetics of the elementary reactions involved in the cascade of events leading from the first-formed water-soluble benzyloxyl radical to superoxide have been determined by laser flash photolysis. On the basis of these kinetics it is concluded that SOTS-1 will be suitable for studies of superoxide-induced oxidative stress in most biological systems. A water-assisted 1,2-H shift converting benzyloxyl into the benzyl ketyl radical is an important step in the above reaction cascade. The kinetics of the 1,2-H shift assisted by H 2O, D 2O, and a number of nucleophilic alcohols have been measured for the first time. These data have led to a proposed new mechanism involving the initial formation of a ketyl radical anion and an oxonium cation which generally collapse to give the neutral ketyl radical as the first observable product on the time scale of our experiments (ca. 80 ns).
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Steacie Institute for Molecular Sciences (SIMS-ISSM)
Peer reviewedYes
NPARC number21276553
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Record identifier12a7b8ad-982f-4244-8379-e1edf58888ed
Record created2015-10-13
Record modified2017-03-23
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