Peroxynitrous acid

Peroxynitrous acid
Names
	Preferred IUPAC name Peroxynitrous acid
	Systematic IUPAC name (Hydridodioxido)oxidonitrogen
Identifiers
CAS Number	14691-52-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:25942 ;
ChEMBL	ChEMBL1794794 ;
ChemSpider	109951 ;
Gmelin Reference	49207
MeSH	Peroxynitrous+Acid
PubChem CID	123349;
CompTox Dashboard (EPA)	DTXSID00163543 ;
	InChI InChI=1S/HNO3/c2-1-4-3/h3H Key: CMFNMSMUKZHDEY-UHFFFAOYSA-N ;
	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

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. Peroxynitrous acid is also important in atmospheric chemistry.