Hydroxylamine

HydrazineHydroxylamine is an inorganic compound with the formula NH2OH. The pure material is a white, unstable crystalline, hygroscopic compound. However, hydroxylamine is almost always provided and used as an aqueous solution. It is used to prepare oximes, an important functional group. It is also an intermediate in biological nitrification. In biological nitrification, the oxidation of NH3 to hydroxylamine is mediated by the enzyme ammonia monooxygenase (AMO). Hydroxylamine oxidoreductase (HAO) further oxidizes hydroxylamine to nitrite. Hydroxylamine is an inorganic compound with the formula NH2OH. The pure material is a white, unstable crystalline, hygroscopic compound. However, hydroxylamine is almost always provided and used as an aqueous solution. It is used to prepare oximes, an important functional group. It is also an intermediate in biological nitrification. In biological nitrification, the oxidation of NH3 to hydroxylamine is mediated by the enzyme ammonia monooxygenase (AMO). Hydroxylamine oxidoreductase (HAO) further oxidizes hydroxylamine to nitrite. Hydroxylamine was first prepared as hydroxylamine hydrochloride 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). NH2OH can be produced via several routes. The main route is via the Raschig process: aqueous ammonium nitrite is reduced by HSO3− and SO2 at 0 °C to yield a hydroxylamido-N,N-disulfonate anion: This anion is then hydrolyzed to give (NH3OH)2SO4: Solid NH2OH can be collected by treatment with liquid ammonia. Ammonium sulfate, (NH4)2SO4, a side-product insoluble in liquid ammonia, is removed by filtration; the liquid ammonia is evaporated to give the desired product.