Peroxynitrous acid

Peroxynitrous acid (HNO₃) is a reactive nitrogen species (RNS). It is the conjugate acid of peroxynitrite (ONOO⁻). It has a pK_a of approximately 6.8. It is formed in vivo from the diffusion-controlled reaction of nitrogen monoxide (ON^•) and superoxide (O^•−
₂). It is an isomer of nitric acid and isomerises with a rate constant of k = 1.2 s⁻¹, a process whereby up to 5% of hydroxyl and nitrogen dioxide radicals may be formed. It oxidises and nitrates aromatic compounds in low yield. The mechanism may involve a complex between the aromatic compound and ONOOH, and a transition from the cis- to the trans-configuration of ONOOH.^[3] Peroxynitrous acid is also important in atmospheric chemistry.

Peroxynitrous acid

Names
Preferred IUPAC name Peroxynitrous acid[citation needed]
Systematic IUPAC name (Hydridodioxido)oxidonitrogen[1][2]
Identifiers
CAS Number	14691-52-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:25942 Y
ChEMBL	ChEMBL1794794 Y
ChemSpider	109951 Y
Gmelin Reference	49207
MeSH	Peroxynitrous+Acid
PubChem CID	123349
CompTox Dashboard (EPA)	DTXSID00163543
InChI InChI=1S/HNO3/c2-1-4-3/h3H Y Key: CMFNMSMUKZHDEY-UHFFFAOYSA-N Y
SMILES OON=O
Properties
Chemical formula	NHO 3
Molar mass	63.0128 g mol−1
Conjugate base	Peroxynitrite
Related compounds
Related compounds	Nitroxyl Nitrous acid Nitrosyl bromide Nitrosyl chloride Nitrosyl fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references