Sodium cyanide

Sodium cyanide
Sodium cyanide
CAS number 143-33-9 YesY
PubChem 8929
ChemSpider 8587 YesY
UN number 1689
RTECS number VZ7525000
Jmol-3D images Image 1
Molecular formula NaCN
Molar mass 49.0072 g/mol
Appearance white solid
Density 1.595 g/cm3
Melting point

563.7 °C

Boiling point

1496 °C

Solubility in water 58 g/100 ml (20 °C) (hydrate solubility), 82 g/100 ml (34.7 °C)
Refractive index (nD) 1.45
EU Index 006-007-00-5
EU classification Very toxic (T+)
Dangerous for the environment (N)Corrosive (C) [1]
R-phrases R26/27/28, R32, R50/53
S-phrases (S1/2), S7, S28, S29, S45, S60, S61
NFPA 704
NFPA 704.svg
Flash point Non-flammable
LD50 5.8–15 mg/kg (oral in rats, mice)[2]
Related compounds
Other cations Potassium cyanide
Related compounds Hydrogen cyanide
 N cyanide (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium cyanide is an inorganic compound with the formula NaCN. This highly toxic colorless salt is used mainly in gold mining but has other niche applications. It is an inorganic salt derived from neutralization reactions involving the weak acid hydrogen cyanide.


Production and chemical properties

Sodium cyanide is produced by treating hydrogen cyanide with sodium hydroxide:[3]

HCN + NaOH → NaCN + H2O

Worldwide production was estimated at 500,000 tons in the year 2006. In former times, it was prepared by the Castner-Kellner process involving the reaction of sodium amide with carbon at elevated temperatures.

NaNH2 + C → NaCN + H2

The structure of solid NaCN is related to that of sodium chloride.[4] The anions and cations are each six-coordinate (potassium chloride (KCN) has a similar structure). Each Na+ forms pi-bonds to two CN- groups as well as two "bent" Na---CN and two "bent" Na---NC links.[5]

Because the salt is derived from a weak acid, NaCN readily reverts back to HCN by 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[6]). 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 (H2O2) to produce sodium cyanate (NaOCN) and water:[3]

NaCN + H2O2 → NaOCN + H2O


Cyanide mining

Sodium gold cyanide

Sodium cyanide is mainly used to extract gold and other precious metals in mining. This application exploits the high affinity of gold(I) for cyanide, which induces gold metal to oxidize and dissolve in the presence of air and water, producing the salt sodium gold cyanide (or gold sodium cyanide) and sodium hydroxide:

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 gold cyanide (KAu(CN2)).

Few other methods exist for this extraction process.

Chemical feedstock

Several commercially significant chemical compounds are derived from cyanide, including cyanuric chloride, cyanogen chloride, and many nitriles. In organic synthesis, cyanide, which is classified as a strong nucleophile, is used to prepare nitriles, which occur widely in many specialty chemicals, including pharmaceuticals.

Niche uses

Being highly toxic, sodium cyanide is used to kill or stun rapidly such as in illegal cyanide fishing and in collecting jars used by entomologists.


Cyanide salts are among the most rapidly acting of all known poisons. Cyanide is a potent inhibitor of 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.


  1. ^ Oxford MSDS
  2. ^ Martel, B.; Cassidy, K. (2004). Chemical Risk Analysis: A Practical Handbook. Butterworth–Heinemann. pp. 361. ISBN 1903996651. 
  3. ^ a b 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. doi:10.1002/14356007.i01_i01
  4. ^ Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
  5. ^ H. T. Stokes, D. L. Decker, H. M. Nelson, J. D. Jorgensen (1993). "Structure of potassium cyanide at low temperature and high pressure determined by neutron diffraction". Phys. Rev. B 47 (17): 11082–11092. doi:10.1103/PhysRevB.47.11082. 
  6. ^ Online 'Mendelian Inheritance in Man' (OMIM) 304300

See also

External links

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Look at other dictionaries:

  • sodium cyanide — n. a white, highly poisonous salt, NaCN, used in electroplating, as an insecticide, etc …   English World dictionary

  • sodium cyanide — natrio cianidas statusas T sritis chemija formulė NaCN atitikmenys: angl. sodium cyanide rus. натрий цианистый; натрия цианид …   Chemijos terminų aiškinamasis žodynas

  • sodium cyanide — an extremely poisonous compound, NaCN, used for various industrial processes and to fumigate fruit trees. See also cyanide poisoning, under poisoning …   Medical dictionary

  • sodium cyanide — noun a white poisonous salt (NaCN) used in electroplating • Hypernyms: ↑cyanide …   Useful english dictionary

  • sodium cyanide — Chem. a white, crystalline, deliquescent, water soluble, poisonous powder, NaCN, prepared by heating sodium amide with charcoal: used chiefly in casehardening alloys, in the leaching and flotation of ore, and in electroplating. [1880 85] * * * …   Universalium

  • sodium cyanide — noun Date: 1885 a white deliquescent poisonous salt NaCN used especially in electroplating, in fumigating, and in treating steel …   New Collegiate Dictionary

  • sodium cyanide — so′dium cy′anide n. chem. a white, crystalline, water soluble, poisonous powder, NaCN, used chiefly in casehardening alloys, in the leaching and flotation of ore, and in electroplating • Etymology: 1880–85 …   From formal English to slang

  • Cyanide poisoning — Classification and external resources Cyanide ion ICD 10 T …   Wikipedia

  • Sodium nitroprusside — Sodium nitroprusside …   Wikipedia

  • Cyanide fishing — is a method of collecting live fish mainly for use in aquariums, which involves spraying a sodium cyanide mixture into the desired fish s habitat in order to stun the fish. The practice hurts not only the target population, but also many other… …   Wikipedia

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