|Preferred IUPAC name
|Systematic IUPAC name
Hyponitrous acid dimer
3D model (JSmol)
|Molar mass||62.0282 g/mol|
|Main hazards||explosive when dry|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Hyponitrous acid is a chemical compound with formula or HON=NOH. It is an isomer of nitramide, H2N-NO2.
There are two possible structures of hyponitrous acid, trans and cis. Trans-hyponitrous acid forms white crystals that are explosive when dry. In aqueous solution, it is a weak acid (pKa1 = 7.21, pKa2 = 11.54), and decomposes to nitrous oxide and water with a half life of 16 days at 25 °C at pH 1-3:
Since this reaction is not reversible, should not be considered as the anhydride of .
Spectroscopic data indicate a trans configuration for the resulting acid.