hydrogen cyanide


hydrogen cyanide
a colorless poisonous gas, HCN, having a bitter almondlike odor: in aqueous solution it forms hydrocyanic acid.
[1880-85]

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also called  formonitrile (HCN) 

      a highly volatile, colourless, and extremely poisonous liquid (boiling point 26° C [79° F], freezing point -14° C [7° F]). A solution of hydrogen cyanide in water is called hydrocyanic acid, or prussic acid. It was discovered in 1782 by a Swedish chemist, Carl Wilhelm Scheele (Scheele, Carl Wilhelm), who prepared it from the pigment Prussian blue. Hydrogen cyanide and its compounds are used for many chemical processes, including fumigation, the case hardening of iron and steel, electroplating, and the concentration of ores. It also is employed in the preparation of acrylonitrile, which is used in the production of acrylic fibres, synthetic rubber, and plastics.

      Hydrogen cyanide is highly toxic because it inhibits cellular oxidative processes. An adult human can withstand 50–60 parts of hydrogen cyanide per million parts of air for an hour without serious consequences, but exposure to concentrations of 200–500 parts per million of air for 30 minutes is usually fatal. A method of inflicting capital punishment consists of administering a fatal dose of hydrogen cyanide gas.

      Hydrogen cyanide may be isolated in small quantities from plants, where it occurs in combination with sugars. Large quantities of hydrogen cyanide for laboratory and commercial use are synthesized by three principal methods: (1) treatment of sodium cyanide with sulfuric acid; (2) catalytic oxidation of a methane–ammonia mixture; and (3) decomposition of formamide (HCONH2).

      Hydrogen cyanide is an excellent solvent for many salts, but it is not widely used as a solvent because of its toxicity. In pure form, hydrogen cyanide is a stable compound, but it polymerizes readily in the presence of basic substances, such as ammonia or sodium cyanide. The salts are used in the extraction of ores, in electrolytic processes, and in the treatment of steel. Among the important reactions with organic compounds are those with aldehydes and ketones, forming cyanohydrins, which serve as intermediates in many organic syntheses, and with ethylene oxide, forming an intermediate product that is converted to acrylonitrile (CH2=CHCN).

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Universalium. 2010.

Look at other dictionaries:

  • Hydrogen cyanide — IUPAC name …   Wikipedia

  • hydrogen cyanide — n 1) a poisonous usu. gaseous compound HCN that has the odor of bitter almonds 2) HYDROCYANIC ACID * * * an extremely poisonous colorless liquid or gas, HCN, a decomposition product of various naturally occurring glycosides and a common cause of… …   Medical dictionary

  • hydrogen cyanide — Hydrocyanic Hy dro*cy*an ic, a. [Hydro , 2 + anic: cf. F. hydrocyanique.] (Chem.) Pertaining to, or derived from the combination of, hydrogen and cyanogen. [1913 Webster] {Hydrocyanic acid} (Chem.), a colorless, mobile, volatile liquid, {HCN},… …   The Collaborative International Dictionary of English

  • hydrogen cyanide — cianido rūgštis statusas T sritis chemija formulė HCN atitikmenys: angl. hydrocyanic acid; hydrogen cyanide; Prussian acid rus. синильная кислота; цианистоводородная кислота; циановодород ryšiai: sinonimas – vandenilio cianidas …   Chemijos terminų aiškinamasis žodynas

  • hydrogen cyanide — noun Date: 1869 1. a poisonous usually gaseous compound HCN that has the odor of bitter almonds 2. hydrocyanic acid …   New Collegiate Dictionary

  • hydrogen cyanide — noun A colourless, very poisonous, volatile liquid, HCN, used in the production of dyes, plastics and fumigants; it dissolves in water to form hydrocyanic acid and reacts with bases to form cyanides, and with some …   Wiktionary

  • hydrogen cyanide — noun Chemistry a highly poisonous gas or volatile liquid with an odour of bitter almonds, made by the action of acids on cyanides. [HCN.] …   English new terms dictionary

  • hydrogen cyanide — hy′drogen cy′anide n. chem. a colorless poisonous gas, HCN, having a bitter almondlike odor: in aqueous solution it forms hydrocyanic acid …   From formal English to slang

  • hydrogen cyanide — /haɪdrədʒən ˈsaɪənaɪd/ (say huydruhjuhn suyuhnuyd) noun a highly poisonous, volatile gas, HCN, with an odour of bitter almonds …   Australian English dictionary

  • hydrogen cyanide — noun a highly poisonous gas or volatile liquid that smells like bitter almonds; becomes a gas at around 90 degree Fahrenheit and is most dangerous when inhaled; the anhydride of hydrocyanic acid; used in manufacturing • Hypernyms: ↑compound,… …   Useful english dictionary


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