Title: Cyanogen
CAS Registry Number: 460-19-5
CAS Name: Ethanedinitrile
Additional Names: dicyan; oxalic acid dinitrile
Molecular Formula: C2N2
Molecular Weight: 52.03
Percent Composition: C 46.17%, N 53.84%
Line Formula: NºC-CºN
Literature References: Prepn by adding an aq soln of sodium or potassium cyanide to an aq soln of copper(II) sulfate or chloride: Janz, Inorg. Synth. 5, 43 (1957); from HCN by the use of CuO: Fierce, Millikan, US 2841472 (1958 to Pure Oil); from HCN and NO2: Fierce, Sander, Ind. Eng. Chem. 53, 985 (1961). Review: Brotherton, Lynn, Chem. Rev. 59, 841-883 (1959). Review of toxicology and human exposure: Toxicological Profile for Cyanide (PB98-101207, 1997) 291 pp.
Properties: Highly poisonous gas. Almond-like odor. Acrid and pungent when in lethal concns. Burns with pink flame having a bluish border. mp -27.9° (also reported as -34.4°). bp -21.17°. d4-21.17 0.9537. Heat of vaporization (liquid) 5.778 kcal/mole. Above 500° polymerizes to insol paracyanogen (CN)n. One vol of water dissolves about 4 vols of cyanogen gas. Also sol in alcohol, ether. Slowly hydrolyzed in aq soln giving oxalic acid and ammonia.
Melting point: mp -27.9° (also reported as -34.4°)
Boiling point: bp -21.17°
Density: d4-21.17 0.9537
CAUTION: Potential symptoms of overexposure are irritation of eyes, nose, upper respiratory system; lacrimation; cherry red lips; tachypnea, hyperpnea, bradycardia; headache, vertigo, convulsions; dizziness, loss of appetite, weight loss. Direct contact with liquid may cause frostbite. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 82.
Cyanogen Azide Cyanogen Bromide Cyanogen Chloride Cyanogen Iodide Cyanopsin

Skeletal formula of cyanogen
Ball and stick model of cyanogen Spacefill model of cyanogen
CAS number 460-19-5 YesY
PubChem 9999
ChemSpider 9605 YesY
EC number 207-306-5
UN number 1026
MeSH cyanogen
ChEBI CHEBI:29308 YesY
RTECS number GT1925000
Beilstein Reference 1732464
Gmelin Reference 1090
Jmol-3D images Image 1
Molecular formula C2N2
Molar mass 52.03 g mol−1
Appearance Colourless gas
Odor pungent, almond-like
Density 950 mg mL−1 (at −21 °C)
Melting point −28 °C; −18 °F; 245 K
Boiling point −21.1 °C; −6.1 °F; 252.0 K
Solubility in water 45 g/100 mL (at 20 °C)
Solubility soluble in ethanol, ethyl ether
kH 1.9 μmol Pa−1 kg−1
Refractive index (nD) 1.327 (18 °C)
Std molar
entropy So298
241.57 J K−1 mol−1
Std enthalpy of
formation ΔfHo298
309.07 kJ mol−1
Std enthalpy of
combustion ΔcHo298
−1.0978–−1.0942 MJ mol−1
EU Index 608-011-00-8
EU classification Flammable F+ Toxic T Dangerous for the Environment (Nature) N
R-phrases R12, R23, R50/53
S-phrases (S1/2), S16, S33, S45, S63
NFPA 704
NFPA 704.svg
Explosive limits 6.6–42.6%
Related compounds
Related alkanenitriles
  • Hydrogen cyanide
  • Thiocyanic acid
  • Cyanogen iodide
  • Cyanogen bromide
  • Cyanogen chloride
  • Cyanogen fluoride
  • Acetonitrile
  • Aminoacetonitrile
  • Glycolonitrile
  • Propanenitrile
  • Aminopropionitrile
  • Malononitrile
  • Pivalonitrile
  • Acetone cyanohydrin
Related compounds DBNPA
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Cyanogen is the chemical compound with the formula (CN)2. It is a colorless, toxic gas with a pungent odor. The molecule is a pseudohalogen. Cyanogen molecules consist of two CN groups – analogous to diatomic halogen molecules, such as Cl2, but far less oxidizing. The two cyano groups are bonded together at their carbon atoms: N≡C−C≡N, although other isomers have been detected.[4] Certain derivatives of cyanogen are also called "cyanogen" even though they contain only one CN group. For example cyanogen bromide has the formula NCBr.[5]

Cyanogen is the anhydride of oxamide:

H2NC(O)C(O)NH2 → NCCN + 2 H2O

although oxamide is manufactured from cyanogen by hydrolysis:[6]

NCCN + 2 H2O → H2NC(O)C(O)NH2