Editing Sodium cyanide

{{short description|Toxic chemical compound (NaCN)}}
{{chembox
| Verifiedfields = changed
| Watchedfields  = changed
| verifiedrevid  = 464400731
| Name           = Sodium cyanide
| ImageFile      = Sodium cyanide.svg
| ImageFile1     = Sodium-cyanide-phase-I-unit-cell-3D-SF.png
| ImageName      = Sodium cyanide bonding
| OtherNames     = 
| IUPACName      = 
| SystematicName = 
| Section1       = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 8587
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 1644697
| InChI = 1S/CN.Na/c1-2;/q-1;+1
| InChIKey = MNWBNISUBARLIT-UHFFFAOYAG
| SMILES = [C-]#N.[Na+]
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/CN.Na/c1-2;/q-1;+1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = MNWBNISUBARLIT-UHFFFAOYSA-N
| CASNo = 143-33-9
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = O5DDB9Z95G
| PubChem = 8929
| RTECS = VZ7525000
| UNNumber = 1689
| EINECS = 205-599-4
  }}
| Section2       = {{Chembox Properties
| Formula = NaCN
| MolarMass = 49.0072 g/mol
| Appearance = white solid
| Odor = faint [[Almond#Sweet and bitter almonds|bitter almond]]-like
| Density = 1.5955 g/cm<sup>3</sup>
| Solubility = 48.15 g/100 mL (10 °C) <br> 63.7 g/100 mL (25 °C)
| SolubleOther = soluble in [[ammonia]], [[methanol]], [[ethanol]] <br> very slightly soluble in [[dimethylformamide]], [[sulfur dioxide|SO<sub>2</sub>]] <br> insoluble in [[dimethyl sulfoxide]]
| MeltingPtC = 563.7
| BoilingPtC = 1496
| RefractIndex = 1.452
  }}
| Section3       = 
| Section4 = {{Chembox Thermochemistry
| Thermochemistry_ref = <ref>{{cite book |url=https://www.worldcat.org/oclc/930681942 |title=CRC handbook of chemistry and physics : a ready-reference book of chemical and physical data. |date=2016 |others=William M. Haynes, David R. Lide, Thomas J. Bruno |isbn=978-1-4987-5428-6 |edition=2016-2017, 97th |location=Boca Raton, Florida |oclc=930681942}}</ref>
| HeatCapacity = 70.4&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup>
| Entropy = 115.6&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup>
| DeltaHform = −87.5&nbsp;kJ·mol<sup>−1</sup>
| DeltaGfree = −76.4&nbsp;kJ·mol<sup>−1</sup>
| DeltaHcombust =
| DeltaHfus = 8.79&nbsp;kJ·mol<sup>−1</sup>
| DeltaHvap =
| DeltaHsublim =
| HHV =
| LHV =
 }}
| Section5       = 
| Section6       = 
| Section7       = {{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics1118.htm ICSC 1118]
| GHSPictograms = {{GHS skull and crossbones}} {{GHS environment}}
| NFPA-H = 4
| NFPA-F = 0
| NFPA-R = 0
| NFPA-S =
| FlashPt = Non-flammable
| LD50 = 4 mg/kg (sheep, oral)<br/>15 mg/kg (mammal, oral)<br/>8 mg/kg (rat, oral)<ref>{{IDLH|cyanides|Cyanides (as CN)}}</ref>
| IDLH = 25 mg/m<sup>3</sup> (as CN)<ref name=PGCH>{{PGCH|0562}}</ref>
| REL = C 5 mg/m<sup>3</sup> (4.7 ppm) [10-minute]<ref name=PGCH/>
| PEL = TWA 5 mg/m<sup>3</sup><ref name=PGCH/>
  }}
| Section8       = {{Chembox Related
| OtherCations = [[Potassium cyanide]]
| OtherCompounds = [[Hydrogen cyanide]]
  }}
}}

'''Sodium cyanide''' is a [[Chemical compound|compound]] with the [[chemical formula|formula]] [[sodium|Na]][[carbon|C]][[nitrogen|N]] and the [[chemical structure|structure]] {{chem2|Na+ -[[cyanide|C\tN]]}}. It is a white, [[Solubility|water-soluble]] solid. [[Cyanide]] has a high affinity for metals, which leads to the high [[toxicity]] of this [[Salt (chemistry)|salt]]. Its main application, in [[gold mining]], also exploits its high reactivity toward metals. It is a [[strong base|moderately strong base]].

==Production and chemical properties==

Sodium cyanide is produced by treating [[hydrogen cyanide]] with [[sodium hydroxide]]:<ref name=Ullmann/>
:{{chem2|HCN  +  NaOH   →   NaCN  +  H2O}}
Worldwide production was estimated at 500,000 tons in the year 2006. Formerly it was prepared by the Castner process involving the reaction of [[sodium amide]] with carbon at elevated temperatures.
:{{chem2|NaNH2  +  C   →   NaCN  +  H2}}

The structure of solid NaCN is related to that of [[sodium chloride]].<ref>Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. {{ISBN|0-19-855370-6}}.</ref> The anions and cations are each six-coordinate. [[Potassium cyanide]] (KCN) adopts a similar structure.<ref>{{cite journal | journal = Phys. Rev. B | volume = 47 | issue = 17 | year = 1993 | pages = 11082–11092 | doi = 10.1103/PhysRevB.47.11082 | title = Structure of potassium cyanide at low temperature and high pressure determined by neutron diffraction |author1=H. T. Stokes |author2=D. L. Decker |author3=H. M. Nelson |author4=J. D. Jorgensen | pmid = 10005242 | bibcode = 1993PhRvB..4711082S | url = https://zenodo.org/record/1233725 | type = Submitted manuscript }}</ref>

When treated with [[acid]], it forms the toxic gas [[hydrogen cyanide]]:
:{{chem2|NaCN + H+  →  HCN + Na+}}

Because the salt is derived from a weak acid, sodium cyanide readily reverts to HCN by [[hydrolysis]]; the moist solid emits small amounts of hydrogen cyanide, which is thought to smell like bitter [[almonds]] (not everyone can smell it—the ability thereof is due to a genetic trait<ref>{{OMIM|304300}}</ref>).  Sodium cyanide reacts rapidly with strong acids to release hydrogen cyanide. This dangerous process represents a significant risk associated with cyanide salts. It is detoxified most efficiently with [[hydrogen peroxide]] ({{chem2|H2O2}}) to produce [[sodium cyanate]] (NaOCN) and water:<ref name="Ullmann" />
:{{chem2|NaCN  +  H2O2  →  NaOCN  +  H2O}}

==Applications==
===Cyanide mining===
{{Anchor|Sodium gold cyanide|Sodium dicyanoaurate}}
[[Gold cyanidation]] (also known as the cyanide process) is the dominant technique for extracting [[gold]], much of which is obtained from low-grade [[ore]]. More than 70% of cyanide consumption globally is used for this purpose.  The  application exploits the high affinity of gold(I) for cyanide, which induces gold metal to oxidize and dissolve in the presence of air (oxygen) and water, producing the salt '''sodium dicyanoaurate''' (or sodium gold cyanide) ({{chem2|NaAu(CN)2}}):<ref name=Ullmann/>
:{{chem2|4 Au  +  8 NaCN  +  O2  +  2 H2O  →  4 Na[Au(CN)2]  +  4 NaOH}}

A similar process uses [[potassium cyanide]] (KCN, a close relative of sodium cyanide) to produce [[potassium dicyanoaurate]] ({{chem2|KAu(CN)2}}).

These soluble forms of gold (and silver) can be converted back to the metals by electrolysis.

===Chemical feedstock===
Some commercially significant chemicals are derived from cyanide: [[cyanuric chloride]], [[cyanogen chloride]], and [[cyanogen]].<ref name=Ullmann/> 

Several specialty [[nitrile]]s may be produced by alkylation of cyanide, a strong [[nucleophile]]. Illustrative is the synthesis of [[benzyl cyanide]] by the reaction of [[benzyl chloride]] and sodium cyanide:<ref>{{cite journal|last1=Adams|first1=Roger|last2=Thal|first2=A. F.|title=Benzyl cyanide|journal=Organic Syntheses|date=1922|volume=2|page=9|doi=10.15227/orgsyn.002.0009}}</ref>
:{{chem2| C6H5CH2Cl + NaCN -> C6H5CH2CN +  NaCl}}

===Electroplating===
Cyanide baths (solutions) of metal ions are used to [[electroplating|electroplate]] many metals, including [[platinum]], gold, and silver. [[Cadmium]] plating gives excellent corrosion resistance and is achieved using [[cadmium oxide]] and sodium cyanide.<ref>{{cite book |doi=10.1002/14356007.a04_499 |chapter=Cadmium and Cadmium Compounds |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2000 |last1=Schulte-Schrepping |first1=Karl-Heinz |last2=Piscator |first2=Magnus |isbn=978-3-527-30385-4 }}</ref> Copper 'strikes' (thin high quality layers) are traditionally formed using cyanide electroplating, these thin interstitial layers allow adhesion between metals that are usually incompatible, such as chromium and aluminium.{{cn|date=March 2025}}

===Niche uses===
Being highly toxic, sodium cyanide is used to kill or stun rapidly such as in collecting jars used by [[entomologist]]s and in widely illegal [[cyanide fishing]].

It was used as an [[insecticide]], [[rodenticide]] and [[Antibiotic|antibacterial]], but these uses were cancelled by the [[United States Environmental Protection Agency|EPA]] in 1987.<ref>{{Cite web |date=September 1994 |title=Reregistration Eligibility Decision (R.E.D. Facts) Sodium cyanide |url=https://www3.epa.gov/pesticides/chem_search/reg_actions/reregistration/fs_PC-074002_1-Sep-94.pdf |website=United States Environmental Protection Agency}}</ref>

==Toxicity==
{{main|Cyanide poisoning}}
Sodium cyanide, like other soluble cyanide salts, is among the most rapidly acting of all known poisons. NaCN is a potent inhibitor of [[cellular respiration|respiration]], acting on mitochondrial [[cytochrome oxidase]] and hence blocking electron transport. This results in decreased oxidative metabolism and oxygen utilization. [[Lactic acidosis]] then occurs as a consequence of anaerobic metabolism. An oral dosage as small as 200–300&nbsp;mg can be fatal.

==Disposal==
Due to toxicity considerations, the disposal of cyanide is subject to stringent regulations. Industrial cyanide effluent is typically destroyed by oxidation using [[Peroxysulfuric acid (disambiguation)|peroxysulfuric acid]], [[hydrogen peroxide]], [[sulfur dioxide]]/copper salts ("Inco process") or all three ("Combiox Process").  Use of [[sodium hypochlorite]], traditional for laboratory-scale wastes, is impractical on a commercial scale.  Hydrolysis at higher temperatures is highly effective, but requires specialized equipment.  Lastly, cyanide wastes can be acidified for recovery of [[hydrogen cyanide]].<ref name=Ullmann>{{cite book|doi=10.1002/14356007.a08_159.pub3 |chapter=Cyano Compounds, Inorganic |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2011 |last1=Gail |first1=Ernst |last2=Gos |first2=Stephen |last3=Kulzer |first3=Rupprecht |last4=Lorösch |first4=Jürgen |last5=Rubo |first5=Andreas |last6=Sauer |first6=Manfred |last7=Kellens |first7=Raf |last8=Reddy |first8=Jay |last9=Steier |first9=Norbert |last10=Hasenpusch |first10=Wolfgang |isbn=978-3-527-30385-4 }}</ref>

==References==
{{Reflist}}

==External links==
* Institut national de recherche et de sécurité (INRS), [http://www.inrs.fr/publications/bdd/doc/fichetox.html?refINRS=FT%20111 "Cyanure de sodium. Cyanure de potassium"], ''Fiche toxicologique n° 111'', Paris, 2006, 6 pp. (PDF file, ''in French'')
* [http://www.inchem.org/documents/icsc/icsc/eics1118.htm International Chemical Safety Card 1118]
* [http://www.inchem.org/documents/cicads/cicads/cicad61.htm Hydrogen cyanide and cyanides] ([[CICAD]] 61)
* [https://web.archive.org/web/20060517035532/http://www.npi.gov.au/database/substance-info/profiles/29.html National Pollutant Inventory - Cyanide compounds fact sheet]
* [https://www.cdc.gov/niosh/npg/npgd0562.html NIOSH Pocket Guide to Chemical Hazards]
* {{EINECSLink|205-599-4}}
* {{PubChem}}
* [http://www.reptox.csst.qc.ca/Produit.asp?no_produit=4275&nom=Sodium+cyanide CSST (Canada)]
* [http://www.cerc.usgs.gov/pubs/center/pdfdocs/90972.pdf Sodium cyanide hazards to fish and other wildlife from gold]
{{Sodium compounds}}
{{Cyanides}}
{{Molecules detected in outer space}}
{{Authority control}}

[[Category:Cyanides]]
[[Category:Photographic chemicals]]
[[Category:Sodium compounds]]