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Product name hydroxylamine
GOST no data
CAS 7803-49-8

Hydroxylamine NH2OH is colorless, highly hygroscopic, crystalline solid. It is fully miscible in water, ethanol, methanol; almost insoluble in diethyl ether, benzene, toluene, aliphatic hydrocarbons. Molten hydroxylamine can be easily overcooled. Liquid hydroxylamine readily dissolves many inorganic compounds such as ammonia NH3, potassium iodide KI, potassium cyanide KCN, sodium nitrate NaNO3, sodium hydroxide NaOH, sodium chloride and others.

Molecules in crystalline hydroxylamine are packed in rhombic lattice. In gaseous phase it exist in monomer form. It is relatively unstable compound, slowly decomposes above melting point. Can explode if heated up to 100°C in a short time. The rate of decomposition increases in the presence of transition metal ions. Main decomposition products are dinitrogen, ammonia and water.

Being dissolved in water, hydroxylamine shows both acidic (pKa 14.02), and basic (pKa 5.97) properties:

NH2OH + H2O ⇄ H3O+ + NH2O-

NH2OH + H2O ⇄ NH3OH+ + OH-

Hydroxylamine forms stable salts with many mineral acids. Their properties are displayed in a table below. Its hydrochloride and sulfate are reducing agents and able to reduce carbonyl compounds to corresponding oximes. Hydroxylamine is more safely handled, stored and transported in the form of salts.
Salt CAS Melting point, °C Density, g/cm3
(NH2OH)3*H3PO4 20845-01-6 169-171 ----
NH2OH*HCl 5470-11-1 152.4 1.67
(NH2OH)2*H2SO4 10039-54-0 172 ----
NH2OH*HClO4 ---- 89 2.07

Acidic function of hydroxylamine is significantly weaker than basic. It forms only very labile salts with strong bases, such as KH2NO. Due to lone paires on nitrogen and oxygen atoms hydroxylamine forms stable complex compounds with transition and non-transition metals: [Pt(NH2OH)4]Cl2, [Li(NH2OH)3]ClO4, [Ca(NH2OH)3](ClO4)2, [Mg(NH2OH)6](ClO4)2 and so on.

Strong reducing agents like zinc or aluminum dust, hydrogen sulfide, HI, hydrogen upon formation, tin dichloride SnCl2 can reduce hydroxylamine to give ammonia:

NH2OH + Zn(dust) → NH3 + ZnO

Hydroxylamine and its salts readily condense with carbonyl compounds to produce oximes. Reaction with aldehydes gives aldoximes, ketones are converted into ketoximes respectively. This reaction is used in chemical industry as an intermediate stage of ε-caprolactam manufacturing. Cyclohexanone reacts with water solution of hydroxylamine sulfate in the presence of alkali to give cyclohexanone oxime:

cyclohexanone oxime preparation by condensation of cyclohexanone with hydroxylamine

Hydroxylamine can be acylated with carboxylic acid esters, anhydrides or halogen anhydrides to form corresponding hydroxamic acids:


Hydroxylamine and its derivatives are known as toxic and mutagen compounds. It may be absorbed through the skin. Interacting with hemoglobin hydroxylamine converts it into inactive methemoglobin. It may cause eczemas and festering of skin. Hydroxylamine can explode if quickly heated up to 100°C.


There are several ways for industrial hydroxylamine preparation:

  • by hydrogenation of nitrogen(II) oxide in the diluted sulfuric acid at 40°C in the presence of catalyst (platinum at graphite):

    2NO + 3H2 + H2SO4 → (NH2OH)2*H2SO4

  • by reduction of nitric acid with dihydrogen in diluted phosphoric acid in the presence of palladium catalyst:

    HNO3 + 3H2 → NH2OH + 2H2O


  • as an intermediate in caprolactam synthesis;
  • as a source compound for oximes and hydroxamic acids preparation. These adducts are widely used in pharmaceutical industry, perfumery and dyes manufacturing;
  • as a component of developers in photography;
  • hydroxylamine nitrate and perchlorate are used as a rocket fuel as itself and in the mixture with other components;
  • as a stripping agent to remove photoresist after lithography in semiconductor industry;
  • as a titrating agent for carbonyl compounds in organic chemistry;

Manufacturer(s) no data
Chemical structure of hydroxylamine

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