Potassium cyanide

Potassium cyanide

Chembox new
ImageFile = Kaliumcyanid.jpg
ImageSize = 250px
Name = Potassium cyanide
Section1 = Chembox Identifiers
CASNo = 151-50-8
EINECS = 205-792-3
RTECS = TS8750000

Section2 = Chembox Properties
Formula = KCN
MolarMass = 65.12 g/mol
Solvent = other solvents
SolubleOther = 71.6 g/100 ml (25°C)
MeltingPt = 634°C

Section4 = Chembox Thermochemistry
DeltaHf = −131.5 kJ/mol
Entropy = 127.8 J.K–1.mol–1

Section7 = Chembox Hazards
EUClass = Very toxic (T+)
Dangerous for the environment (N)
RPhrases = R26/27/28, R32
SPhrases = S1/2, S7, S28, S29
S45, S60, S61
LD50 = 5–10 mg/kg (oral in rats, mice, rabbits) [Bernard Martel. "Chemical Risk Analysis: A Practical Handbook". Kogan, 2004, page 361. ISBN 1903996651.]

Section8 = Chembox Related
OtherCations = Sodium cyanide
OtherCpds = Hydrogen cyanide

Potassium cyanide is an inorganic compound with the formula KCN. This colorless crystalline compound, similar in appearance to sugar, is highly soluble in water. The vast majority of KCN is used in gold mining followed by use in organic synthesis, and electroplating. Smaller applications include jewelry for chemical gilding and buffing.Andreas Rubo, Raf Kellens, Jay Reddy, Norbert Steier, Wolfgang Hasenpusch "Alkali Metal Cyanides" in Ullmann's Encyclopedia of Industrial Chemistry 2006 Wiley-VCH, Weinheim, Germany.ISBN: 10.1002/14356007.i01 i01]

Highly toxic, KCN is odorless but due to hydrolysis, the moist solid emits small amounts of hydrogen cyanide, which smells like bitter almonds (not everyone can smell it—the ability thereof is due to a genetic trait [OMIM|304300] ). It is also used by entomologists as a killing agent in collecting jars, as most insects succumb within seconds, minimizing damage of even highly fragile specimens.


KCN is produced by treating hydrogen cyanide with potassium hydroxide. Approximately 50,000 tons are produced yearly (the production of sodium cyanide is 10x that amount). It is detoxified most efficiently with hydrogen peroxide::KCN + H2O2 → KOCN + H2O


In gold mining, KCN and NaCN form water-soluble salts from gold metal in the presence of air::4 Au + 8 KCN + O2 + 2 H2O → 4 K [Au(CN)2] + 4 KOHVery few alternative methods exist for this extraction process.

KCN and the related NaCN are widely used in organic synthesis for the preparation of nitriles and carboxylic acids. Illustrative is the Von Richter reaction.


Cyanide is a potent inhibitor of cellular respiration, acting on mitochondrial cytochrome c oxidase and hence blocking oxidative phosphorylation. This prevents the body from oxidising food to produce useful energy. Lactic acidosis then occurs as a consequence of anaerobic metabolism. Initially, acute cyanide poisoning causes a red or ruddy complexion in the victim because the tissues are not able to use the oxygen in the blood. The effects of potassium and sodium cyanide are identical. The person may die within two hours if not treated medically. During this period, convulsions may occur. Death occurs mainly by cardiac arrest.

A number of prominent persons were killed or committed suicide using potassium cyanide, including members of the Nazi and various religious cults. Potassium cyanide (and other forms of cyanide) are a popular method of murder in fiction.


External links

* [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc06/icsc0671.htm International Chemical Safety Card 0671]
* [http://www.inchem.org/documents/cicads/cicads/cicad61.htm Hydrogen cyanide and cyanides] (CICAD 61)
* [http://www.npi.gov.au/database/substance-info/profiles/29.html National Pollutant Inventory - Cyanide compounds fact sheet]
* [http://www.cdc.gov/niosh/npg/npgd0522.html NIOSH Pocket Guide to Chemical Hazards]
* [http://ecb.jrc.it European Chemicals Bureau]
* [http://www.reptox.csst.qc.ca/Produit.asp?no_produit=3533&nom=Potassium+cyanide CSST (Canada)]
* [http://webbook.nist.gov/chemistry/ NIST Standard Reference Database]
* Institut national de recherche et de sécurité (1997). " [http://www.inrs.fr/inrs-pub/inrs01.nsf/inrs01_ftox_view/48145297F4EF18BBC1256CE8005A9FC2/$File/ft111.pdf Cyanure de sodium. Cyanure de potassium] ". "Fiche toxicologique n° 111", Paris:INRS, 6pp. (PDF file, "in French")

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Look at other dictionaries:

  • potassium cyanide — n a very poisonous crystalline salt KCN * * * an extremely poisonous compound, KCN; formerly used medicinally and now used for various industrial processes and to fumigate fruit trees. See also cyanide poisoning, under poisoning …   Medical dictionary

  • potassium cyanide — n. an extremely poisonous, white, crystalline compound, KCN, used in metallurgy for extracting gold, in electroplating, as an insecticide, etc …   English World dictionary

  • potassium cyanide — noun a poisonous salt (KCN) used in electroplating and in photography • Hypernyms: ↑cyanide * * * noun : an exceedingly poisonous deliquescent crystalline salt KCN made usually by heating potassium carbonate and carbon with ammonia and used… …   Useful english dictionary

  • potassium cyanide — kalio cianidas statusas T sritis chemija formulė KCN atitikmenys: angl. potassium cyanide rus. калий цианистый; калия цианид …   Chemijos terminų aiškinamasis žodynas

  • potassium cyanide — noun The potassium salt of hydrocyanic acid, KCN; the colourless crystals are soluble in water, and it is extremely poisonous, and is used in electroplating, the extraction of gold and silver from their ores, and in photography …   Wiktionary

  • potassium cyanide — noun Date: 1869 a very poisonous crystalline salt KCN used especially in gold and silver extraction from ore …   New Collegiate Dictionary

  • potassium cyanide — Chem. a white, granular, water soluble, poisonous powder, KCN, having a faint almondlike odor, used chiefly in metallurgy and photography. [1880 85] * * * …   Universalium

  • potassium cyanide — potas′sium cy′anide n. chem. a white, granular, water soluble, poisonous powder, KCN, having a faint almondlike odor …   From formal English to slang

  • potassium cyanide — /pəˌtæsiəm ˈsaɪənaɪd/ (say puh.taseeuhm suyuhnuyd) noun a white, crystalline, poisonous compound, KCN, used in metallurgy and photography …   Australian English dictionary

  • ferric potassium cyanide — kalio heksacianoferatas(III) statusas T sritis chemija formulė K₃[Fe(CN)₆] atitikmenys: angl. ferric potassium cyanide; potassium ferricyanide; potassium hexacyanoferrate; red potassium prussiate; red prussiate of potash rus. калия… …   Chemijos terminų aiškinamasis žodynas