The reaction of ONOO− with carbonyls: Estimation of the half-lives of ONOOC(O)O− and O2NOOC(O)O−

Abstract

The equilibrium constant for the formation of an adduct between a carbonyl and a hydroperoxide ion varies linearly with the acid dissociation constant of the hydroperoxide. Based on this relationship, the half-life of the adduct formed between ONOO⁻ and CO₂, ONOOC(O)O⁻, is estimated to be shorter than 100 ns. Consequently, this adduct should not play any role whatsoever in chemical or biological systems. O₂NOO⁻ and CO₂ are believed to be involved in a fast equilibrium reaction forming an adduct, O₂NOOC(O)O⁻. This adduct does not appear to homolyse either along the O–O or the N–O bond. Furthermore, at realistic CO₂ concentrations, the equilibrium should be shifted far to the O₂NOO⁻ + CO₂ side. Therefore, the rate of self-decomposition of O₂NOO⁻ into NO₂⁻ and O₂ is unaffected by the presence of bicarbonate.