Hydroxylamine (also known as Hydroxyammonia) is an inorganic compound with the formula . The material is a white crystalline, hygroscopic compound. Hydroxylamine is almost always provided and used as an aqueous solution. It is consumed almost exclusively to produce Nylon-6. It is also an intermediate in biological nitrification. The oxidation of to hydroxylamine is a step in biological nitrification. History Hydroxylamine was first prepared as hydroxylammonium chloride in 1865 by the German chemist Wilhelm Clemens Lossen (1838-1906); he reacted tin and hydrochloric acid in the presence of ethyl nitrate. It was first prepared in pure form in 1891 by the Dutch chemist Lobry de Bruyn and by the French chemist Léon Maurice Crismer (1858-1944). The coordination complex , known as Crismer's salt, releases hydroxylamine upon heating. Production Hydroxylamine or its salts can be produced via several routes but only two are commercially viable. It is also produced naturally as discussed in a section on biochemistry. From nitric oxide is mainly produced as its hydrogen sulfate by the hydrogenation of nitric oxide over platinum catalysts in the presence of sulfuric acid. Raschig process Another route to is the Raschig process: aqueous ammonium nitrite is reduced by and at 0 °C to yield a hydroxylamido-N,N-disulfonate anion: This anion is then hydrolyzed to give hydroxylammonium sulfate : Solid can be collected by treatment with liquid ammonia. Ammonium sulfate, , a side-product insoluble in liquid ammonia, is removed by filtration; the liquid ammonia is evaporated to give the desired product. The net reaction is: Hydroxylammonium salts can then be converted to hydroxylamine by neutralization: Other methods Julius Tafel discovered that hydroxylamine hydrochloride or sulfate salts can be produced by electrolytic reduction of nitric acid with HCl or respectively: Hydroxylamine can also be produced by the reduction of nitrous acid or potassium nitrite with bisulfite: (100 °C, 1 h) Reactions Hydroxylamine reacts with electrophiles, such as alkylating agents, which can attach to either the oxygen or the nitrogen atoms: The reaction of with an aldehyde or ketone produces an oxime. (in NaOH solution) This reaction is useful in the purification of ketones and aldehydes: if hydroxylamine is added to an aldehyde or ketone in solution, an oxime forms, which generally precipitates from solution; heating the precipitate with an inorganic acid then restores the original aldehyde or ketone. Oximes such as dimethylglyoxime are also employed as ligands. reacts with chlorosulfonic acid to give hydroxylamine-O-sulfonic acid, a