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HYDROXYLAMINE, NH2OH

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Originally appearing in Volume V14, Page 171 of the 1911 Encyclopedia Britannica.
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HYDROXYLAMINE, NH2OH , or hydroxy-See also:ammonia, a See also:compound prepared in 1865 by W. C. Lossen by the reduction of See also:ethyl nitrate with See also:tin and hydrochloric See also:acid. In 187o E. See also:Ludwig and T. H. Hein (Chem. Centralblatt, 187o, 1, p. 340) obtained it by passing nitric See also:oxide through a See also:series of bottles containing tinand hydrochloric acid, to which a small quantity of See also:platinum tetrachloride has been added; the acid liquid is poured off when the operation is completed, and sulphuretted See also:hydrogen is passed in; the tin sulphide is filtered off and the filtrate evaporated. The See also:residue is extracted by See also:absolute See also:alcohol, which dissolves the hydroxylamine hydrochloride and a little ammonium chloride; this last substance is removed as ammonium platinochloride, and the residual hydroxylamine hydrochloride is recrystallized. E. See also:Divers obtains it by mixing See also:cold saturated solutions containing one molecular proportion of See also:sodium nitrate, and two molecular proportions of acid sodium sulphite, and then adding a saturated See also:solution of See also:potassium chloride to the mixture.

After See also:

standing for twenty-four See also:hours, hydroxylamine potassium disulphonate crystallizes out. This is boiled for some hours with See also:water and the solution cooled, when potassium sulphate separates first, and then hydroxylamine sulphate. E. Tafel (Zeit. anorg. Chem., 1902, 31, p. 289) patented an electrolytic See also:process, wherein 5o% sulphuric acid is treated in a divided See also:cell provided with a See also:cathode of amalgamated See also:lead, 5o% nitric acid being gradually run into the cathode compartment. Pure anhydrous hydroxylamine has been obtained by C. A. Lobry de Bruyn from the hydrochloride, by dissolving it in absolute methyl alcohol and then adding sodium methylate. The precipitated sodium chloride is filtered, and the solution of hydroxyl-amine distilled in See also:order to remove methyl alcohol, and finally fractionated under reduced pressure. The See also:free See also:base is a colourless, odourless, crystalline solid, melting at about 3o° C., and boiling at 58° C. (under a pressure of 22 mm.).

It deliquesces and oxidizes on exposure, inflames in dry See also:

chlorine and is reduced to ammonia by See also:zinc dust. Its aqueous solution is strongly alkaline, and with acids it forms well-defined See also:stable salts. E. Ebler and E. Schott (J. pr. Chem., r9o8, 78, p. 289) regard it as acting with the See also:formula See also:NH2.OH towards bases, and as NH3:0 towards acids, the salts in the latter See also:case being of the oxonium type. It is a strong reducing See also:agent, giving a precipitate of cuprous oxide from alkaline See also:copper solutions at See also:ordinary temperature, converting mercuric chloride to mercurous chloride, and precipitating metallic See also:silver from solutions of silver salts. With See also:aldehydes and See also:ketones it forms See also:oximes (q.v.). W. R. See also:Dunstan (Jour.

Chem. See also:

Soc., 1899, 75, p. 792) found that the addition of methyl iodide to a methyl alcohol solution of hydroxylamine resulted in the formation of trimethyloxamine, N(See also:CH3)30. Many substituted hydroxylamines are known, substitution taking See also:place either in the a or # position (NH2.OH). 9-phenylhydroxylamine, C6HSNH•OH•, is obtained in the reduction of See also:nitrobenzene in neutral solution (e.g. by the See also:action of the See also:aluminium-See also:mercury couple and water), but better, according to C. See also:Goldschmidt (Ber., 1896, 29, p. 2307) by dissolving nitrobenzene in ten times its See also:weight of See also:ether containing a few cubic centimetres of water, and See also:heating with excess of zinc dust and anhydrous See also:calcium chloride for three hours on a water See also:bath. It also appears as an intermediate product in the electrolytic reduction of nitrobenzene in sulphuric acid solution. By See also:gentle oxidation it yields nitrosobenzene. Derivatives of the type R2N.OH result in the action of the Grignard reagent on amyl nitrite. Dihydroxy-ammonia or nitroxyl, NH(OH)2, a very unstable and highly reactive substance, has been especially studied by A. Angeli (see A.

W. See also:

Stewart, See also:Recent Advances in See also:Physical and Inorganic See also:Chemistry, 1909).

End of Article: HYDROXYLAMINE, NH2OH

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