Free radical formation in the peroxynitrous acid (ONOOH)/peroxynitrite (ONOO-) system.
The rate constant of homolysis of peroxynitrite, ONOO-, into O2- and NO was determined to be 0.017 s-1 at 20 degrees C. In combination with other experimental data taken from the literature, this value yields the Gibbs free energy of formation of ONOO-, delta f G o(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 delta f G o(ONOOH) = 7.7 kcal/mol. The rate constant of the reaction between NO and ONOO- was found to be 5 x 10(-)2 M-1 s-1 at most. The implications of the two homolysis reactions are discussed.
Merényi
G
G
Department of Chemistry, Nuclear Chemistry, The Royal Institute of Technology, S-10044 Stockholm 70, Sweden.
Lind
J
J
D005609:Free Radicals; D009566:Nitrates / Q000737:chemistry*; D009608:Nitrous Acid / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D030421:Peroxynitrous Acid
D005609:Free Radicals; D009566:Nitrates; D016877:Oxidants; D030421:Peroxynitrous Acid; C039642:peroxynitric acid; D009608:Nitrous Acid