Nitrohydroxylamine, HO-NH-NO₂

Nitrohydroxylamine, HO-NH-NO₂, or , is obtained in the form of salts by the action of ethyl nitrate on alcoholic hydroxylamine. When the salts, e.g. Na₂N₂O₃, are acidified, the free acid instantly decomposes into nitric oxide and water, or nitrous and hyponitrous acids:

H₂N₂O₃ = 2NO + H₂O;
2H₂N₂O₃ = 2HNO₂ + H₂N₂O₂.

The sodium salt, made by the above reaction in methyl alcohol, is a white powder, soluble and deliquescent. It absorbs oxygen from the air, giving NaNO₂ and NaNO₃. The aqueous solution when boiled decomposes into nitrite and nitrous oxide:

2Na₂N₂O₃ + H₂O = 2NaNO₂ + N₂O + 2NaOH.

The salts of the calcium group, e.g. CaN₂O₃.3½H₂O, are sparingly soluble. The silver salt is almost insoluble. Salts of cadmium and mercury have also been prepared.

A great number of organic derivatives of the above are known under the name of diazo-compounds, as well as derivatives of compounds which have not yet been prepared in the free state, such as R.N₂O₂.H, derived from nitrosohydroxylamine, HO-NH-NO, which is isomeric with nitramide.