Английская Википедия:Hyponitrous acid

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Шаблон:Chembox Hyponitrous acid is a chemical compound with formula Шаблон:Chem or HON=NOH. It is an isomer of nitramide, H2N−NO2; and a formal dimer of azanone, HNO.

Hyponitrous acid forms two series of salts, the hyponitrites containing the [ON=NO]2− anion, and the "acid hyponitrites" containing the [HON=NO] anion.[1]

Structure and properties

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:

<chem>H2N2O2 -> H2O + N2O</chem>

Since this reaction is not reversible, Шаблон:Chem should not be considered as the anhydride of Шаблон:Chem.[1]

The cis acid is not known,[1] but its sodium salt can be obtained.[2]

Preparation

Hyponitrous acid (trans) can be prepared from silver(I) hyponitrite and anhydrous HCl in ether:

<chem>Ag2N2O2 + 2 HCl -> H2N2O2 + 2 AgCl</chem>

Spectroscopic data indicate a trans configuration for the resulting acid.[2]
It can also be synthesized from hydroxylamine and nitrous acid:

<chem>NH2OH + HNO2 -> H2N2O2 + H2O</chem>

Biological aspects

In enzymology, a hyponitrite reductase is an enzyme that catalyzes the chemical reaction[3]

<chem>H2N2O2 + 2 NADH + 2 H+ <-> 2 NH2OH + 2 NAD+</chem>

References

Шаблон:Reflist

Шаблон:Hydrogen compounds Шаблон:Nitrogen compounds