{{Short description|Highly toxic crystalline salt}}{{Use dmy dates|date=June 2018}}{{chembox|Verifiedfields = changed|Watchedfields = changed|verifiedrevid = 464211374|ImageFile1 = Potassium-cyanide-phase-I-unit-cell-3D-SF.png|ImageFile2 = Kaliumcyanid.jpg|IUPACName = Potassium cyanide|Section1={{Chembox Identifiers

correct|chemspider}}|ChemSpiderID = 8681

correct|FDA}}|UNII = MQD255M2ZO|InChI = 1/CN.K/c1-2;/q-1;+1|InChIKey = NNFCIKHAZHQZJG-UHFFFAOYAH|SMILES = [K+].[C-]#N

correct|chemspider}}|StdInChI = 1S/CN.K/c1-2;/q-1;+1

correct|chemspider}}|StdInChIKey = NNFCIKHAZHQZJG-UHFFFAOYSA-N|CASNo = 151-50-8

correct|CAS}}|EINECS = 205-792-3|RTECS = TS8750000|UNNumber = 1680

changed|EBI}}|ChEBI = 33191|PubChem = 9032}}|Section2={{Chembox Properties|Formula = KCN|MolarMass = 65.12 g/mol|Appearance = White crystalline solid deliquescent|Odor = faint, almond-like|Density = 1.52 g/cm3|Solubility = 71.6 g/100 ml (25 Â°C) 100 g/100 ml (100 Â°C)|Solvent1 = methanol|Solubility1 = 4.91 g/100 ml (20 Â°C)|Solvent2 = glycerol|Solubility2 = soluble|Solvent3 = formamide|Solubility3 = 14.6 g/100 mL|Solvent4 = ethanol|Solubility4 = 0.57 g/100ml|Solvent5 = hydroxylamine|Solubility5 = 41 g/100 ml|MeltingPtC = 634.5|BoilingPtC = 1625|pKa = 11.0|RefractIndex = 1.410|MagSus = −37.0Â·10âˆ’6 cm3/mol}}|Section3={{Chembox Thermochemistry|DeltaHf = −131.5 kJ/mol|Entropy = 127.8 J K−1 mol−1}}|Section4={{Chembox Hazards|ExternalSDS = ICSC 0671|GHSPictograms = {{GHS05}}{{GHS06}}{{GHS08}}{{GHS09}}|GHSSignalWord = Danger

290

310

370

410}}

260

273

284|301+310}}|NFPA-H = 4|NFPA-F = 0|NFPA-R = 0|FlashPt = Non-flammable

cyanides|Cyanides (as CN)}}

0522}}|REL = C 5 mg/m3 (4.7 ppm) [10-minute]|PEL = TWA 5 mg/m3}}WEB,weblink POTASSIUM CYANIDE | CAMEO Chemicals | NOAA, |Section5={{Chembox Related|OtherAnions = Potassium cyanate Potassium thiocyanate|OtherCations = Sodium cyanide Rubidium cyanide lithium cyanide caesium cyanide|OtherCompounds = Hydrogen cyanide}}}}Potassium cyanide is a compound with the formula KCN. It is a colorless salt, similar in appearance to sugar, that is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications include jewellery for chemical gilding and buffing.Andreas Rubo, Raf Kellens, Jay Reddy, Joshua Wooten, Wolfgang Hasenpusch "Alkali Metal Cyanides" in Ullmann's Encyclopedia of Industrial Chemistry 2006 Wiley-VCH, Weinheim, Germany. {{doi|10.1002/14356007.i01_i01}} Potassium cyanide is highly toxic, and a dose of 200 to 300 milligrams will kill nearly any human.The moist solid emits small amounts of hydrogen cyanide due to hydrolysis (reaction with water). Hydrogen cyanide is often described as having an odor resembling that of bitter almonds.WEB,weblink Suicide note reveals taste of cyanide, 2006-07-08, Not everyone, however, can smell cyanide; the ability to do so is a genetic trait.{{OMIM|304300}}The taste of potassium cyanide has been described as acrid and bitter, with a burning sensationWEB, à´²àµ‡à´–à´•àµ», à´®à´¾à´§àµà´¯à´®à´‚, 2021-12-19, 'à´¸à´¯à´¨àµˆà´¡àµ à´šà´µàµ¼à´ªàµà´ªà´¾à´£àµ... à´ªàµà´•à´šàµà´šà´¿à´²à´¾à´£àµ...'; à´† 'à´°àµà´šà´¿ à´°à´¹à´¸àµà´¯à´‚' à´ªàµà´±à´¤àµà´¤àµà´µà´¿à´Ÿàµà´Ÿ à´®à´²à´¯à´¾à´³à´¿ à´¨à´Ÿà´¨àµà´¨ à´µà´´à´¿à´¯à´¿à´²àµ‚à´Ÿàµ† {{!, Madhyamam|url=https://www.madhyamam.com/lifestyle/men/about-the-experience-of-malayalee-mp-prasad-who-drank-cyanide-895697|access-date=2021-12-21|website=www.madhyamam.com|language=ml}}{{Unreliable source?|date=September 2023}} similar to lye.WEB, The only taste: Cyanide is acrid,weblink hindustantimes.com, Hindustan Times, 2006-07-08,

Production

KCN is produced by treating hydrogen cyanide with an aqueous solution of potassium hydroxide, followed by evaporation of the solution in a vacuum:{{block indent|HCN + KOH â†’ KCN + H2O}}About 50,000 tons of potassium cyanide are produced yearly.

Historical production

Before 1900 and the invention of the Castner process, potassium cyanide was the most important source of alkali metal cyanides. In this historical process, potassium cyanide was produced by decomposing potassium ferrocyanide:BOOK, Von Wagner, Rudolf, Manual of chemical technology, 1897, D. Appleton & Co., New York, 474 & 477,weblink {{block indent|K4[Fe(CN)6] â†’ 4 KCN + FeC2 + N2}}

Structure

In aqueous solution, KCN is dissociated into hydrated potassium (K+) ions and cyanide (CNâˆ’) ions. As a solid, KCN has structure resembling sodium chloride: with each potassium ion surrounded by six cyanide ions, and vice versa. Despite being diatomic, and thus less symmetric than chloride, the cyanide ions rotate so rapidly that their time-averaged shape is spherical. At low temperature and high pressure, this free rotation is hindered, resulting in a less symmetric crystal structure with the cyanide ions arranged in sheets. Crystallography Open Database, Structure of KCNJOURNAL, Physical Review B, 47, 17, 1993, 11082â€“11092, 10.1103/PhysRevB.47.11082, Structure of potassium cyanide at low temperature and high pressure determined by neutron diffraction, H. T. Stokes, D. L. Decker, H. M. Nelson, J. D. Jorgensen, 10005242, 1993PhRvB..4711082S,weblink Submitted manuscript, .

Applications

KCN and sodium cyanide (NaCN) are widely used in organic synthesis for the preparation of nitriles and carboxylic acids, particularly in the von Richter reaction. It also finds use for the synthesis of hydantoins, which can be useful synthetic intermediates, when reacted with a carbonyl compound such as an aldehyde or ketone in the presence of ammonium carbonate.KCN is used as a photographic fixer in the wet plate collodion process.J. Towler, MD. "The Silver Sunbeam (Facsimile 1864 edition, 1969)" pg 119 The KCN dissolves silver where it has not been made insoluble by the developer. This reveals and stabilizes the image, making it no longer sensitive to light. Modern wet plate photographers may prefer less toxic fixers, often opting for sodium thiosulfate, but KCN is still used.{{anchor|Cyanogen soap}}In the 19th century, cyanogen soap, a preparation containing potassium cyanide, was used by photographers to remove silver stains from their hands.{{rp|p=11}}Reports of Trials for Murder by Poisoning; by Prussic Acid, Strychnia, Antimony, Arsenic, and Aconita. Including the trials of Tawell, W. Palmer, Dove, Madeline Smith, Dr. Pritchard, Smethurst, and Dr. Lamson, with chemical introduction and notes on the poisons used, G. Lathom Browne and C. G. Stewart, London: Stevens and Sons, 1883; redistributed by Project Gutenberg.{{rp|p=73}}"Cyanuret of potassium", Paper, Shadows and Light, Robert Douglas. Accessed 2024-01-20.

Potassium gold cyanide

In gold mining, KCN forms the water-soluble salt potassium gold cyanide (or gold potassium cyanide) and potassium hydroxide from gold metal in the presence of oxygen (usually from the surrounding air) and water:

4 Au + 8 KCN + O2 + 2 H2O â†’ 4 K[Au(CN)2] + 4 KOH

A similar process uses NaCN to produce sodium gold cyanide (NaAu(CN2)).

Toxicity

Potassium cyanide is a potent inhibitor of cellular respiration, acting on mitochondrial cytochrome c oxidase, hence blocking oxidative phosphorylation. 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 cyanide and sodium cyanide are identical, and symptoms of poisoning typically occur within a few minutes of ingesting the substance: the person loses consciousness, and brain death eventually follows. During this period the victim may suffer convulsions. Death is caused by cerebral hypoxia. The expected LD100 dose (human) for potassium cyanide is 200â€“300 mg while the median lethal dose LD50 is estimated at 140 mg.John Harris Trestrail III. Criminal Poisoning - Investigational Guide for Law Enforcement, Toxicologists, Forensic Scientists, and Attorneys (2nd edition). p. 119People who died by suicide, were killed, or killed someone else using potassium cyanide include:

Viktor Meyer, 19th-century German chemist, died by suicide in 1897 after taking cyanideWEB,weblink Top 10 Scientists who Committed Suicide, 2007-10-07,
Gustav Wied, Danish novelist, poet, and playwright, in 1914
Pritilata Waddedar, an Indian revolutionary nationalist, took cyanide in 1932 to avoid capture by Indian Imperial Police, British India
Badal Gupta, a revolutionary from Bengal, who launched an attack on the Writers' Building in Kolkata, consumed cyanide in 1930 immediately after the attack.
Wallace Carothers, polymer chemist who died by suicide in 1937 after battling depression for years
Senior figures in Nazi Germany, such as Erwin Rommel, Hitler's longtime companion Eva Braun, Joseph Goebbels, Heinrich Himmler, and Hermann GÃ¶ring
Alan Turing, a computer scientist who died of cyanide poisoning in 1954
Ronald Clark O'Bryan, a Texas optician who killed his son by lacing a pixy stick with potassium cyanide in 1974
Peoples Temple, the 1978 cult suicide in (Jonestown), Guyana
Members of the LTTE involved in the assassination of Indian prime minister Rajiv Gandhi in 1991
Ramon Sampedro, Spanish tetraplegic and activist whose assisted suicide in 1998 provoked a national debate about euthanasia, and was the subject of the Oscar-winning film "The Sea Inside"
Jason Altom, a promising graduate student in the lab of Nobel Prizeâ€“winning chemist EJ Corey at Harvard, died after drinking potassium cyanide in 1998
Slobodan Praljak, a wartime general in Republic of Croatia, died by suicide by drinking from a vial containing potassium cyanide during the reading of his appeal judgment in The Hague on International Criminal Tribunal for the former Yugoslavia (ICTY) on 29 November 2017.NEWS,weblink War criminal 'took cyanide' in Hague court, 2017-12-01, BBC News, 2017-12-01, en-GB,

It is used by professional entomologists as a killing agent in collecting jars, as insects succumb within seconds to the HCN fumes it emits, thereby minimizing damage to even highly fragile specimens.KCN can be detoxified most efficiently with hydrogen peroxide or with a solution of sodium hypochlorite (NaOCl). Such solutions should be kept alkaline whenever possible so as to eliminate the possibility of generation of hydrogen cyanide:

KCN + H2O2 â†’ KOCN + H2O KCN + NaOCl â†’ KOCN + NaCl

References

External links

International Chemical Safety Card 0671
Hydrogen cyanide and cyanides (CICAD 61)
weblink" title="web.archive.org/web/20060517035532weblink">National Pollutant Inventory - Cyanide compounds fact sheet
NIOSH Pocket Guide to Chemical Hazards
CSST (Canada)
NIST Standard Reference Database
Institut national de recherche et de sÃ©curitÃ© (1997). "weblink$File/ft111.pdf" title="web.archive.org/web/20110927140503weblink$File/ft111.pdf">Cyanure de sodium. Cyanure de potassium". Fiche toxicologique nÂ° 111, Paris:INRS, 6pp. {{in lang|fr}}

- content above as imported from Wikipedia
- "potassium cyanide" does not exist on GetWiki (yet)
- time: 6:03pm EDT - Wed, May 01 2024

[ this remote article is provided by Wikipedia ]

CONNECT