Free Radical Formation in the Peroxynitrous Acid (ONOOH)/Peroxynitrite (ONOO-) System
- 20 March 1998
- journal article
- research article
- Published by American Chemical Society (ACS) in Chemical Research in Toxicology
- Vol. 11 (4) , 243-246
- https://doi.org/10.1021/tx980026s
Abstract
The rate constant of homolysis of peroxynitrite, ONOO-, into O2•- and NO• was determined to be 0.017 s-1 at 20 °C. In combination with other experimental data taken from the literature, this value yields the Gibbs free energy of formation of ONOO-, ΔfG°(ONOO-) = 16.6 kcal/mol. On the basis of this result, we conclude that peroxynitrous acid homolyzes to yield nitrogen dioxide (NO2•) and hydroxyl (OH•) free radicals and derive ΔfG°(ONOOH) = 7.7 kcal/mol. The rate constant of the reaction between NO• and ONOO- was found to be 5 × 10-2 M-1 s-1 at most. The implications of the two homolysis reactions are discussed.Keywords
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