Chapter 41 - Reaction dynamics of aqueous peroxynitrite and peroxynitrous acid

Abstract

The reaction dynamics of peroxynitrite, ONOO-, and peroxynitrous acid, HONOO, are currently subject to intense investigation especially in biomedical sciences. Studies suggest that peroxynitrite is formed in vivo through reactions between nitric oxide and superoxide. Under physiological conditions the peroxynitrite anion becomes partly protonated (pKa=6.8) to form peroxynitrous acid and the two species have been implicated in the onset of numerous degenerative diseases. The need for additional information about these detrimental processes warrants detailed investigations of reactions involving these species. This chapter is thus motivated by the possible formation of peroxynitrite from far-UV photolysis of nitrate. The results presented show that peroxynitrite is produced in high yields in 1 ps. The prompt formation and subsequent protonation of peroxynitrite offers a unique opportunity for studying bimolecular reactions under conditions where secondary reaction can safely be ruled out. The bimolecular reaction kinetics of ONOO‑ + H+→ HONOO as a function of [H+] are measured and are found to be in excellent agreement with seminal theoretical work by Smoluchowsky.