View source for Cyanogen

{{Distinguish|cyanamide|hydrogen cyanide|Cyanide}}
{{for|the Android distribution|CyanogenMod}}
{{Chembox
| Watchedfields = changed
| verifiedrevid = 444495670
| ImageFile = File:Cyanogen 200.svg
| ImageFile_Ref = {{chemboximage|correct|??}}
| ImageSize = 100
| ImageName = Skeletal formula of cyanogen
| ImageFileL1 = Cyanogen-3D-balls.png
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageNameL1 = Ball and stick model of cyanogen
| ImageFileR1 = Cyanogen-3D-vdW.png
| ImageFileR1_Ref = {{chemboximage|correct|??}}
| ImageNameR1 = Spacefill model of cyanogen
| PIN = Oxalonitrile<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 902 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4| chapter = Front Matter}}</ref>
| SystematicName = Ethanedinitrile<ref name=iupac2013 />
| OtherNames = {{ubl|Cyanogen|Bis(nitridocarbon)(''C''—''C'')<ref name=ChEBI>{{Cite web|title=oxalonitrile (CHEBI:29308)| url=https://www.ebi.ac.uk/chebi/searchId.do?chebiId=29308|work=Chemical Entities of Biological Interest|publisher=European Bioinformatics Institute|access-date=6 June 2012|location=UK|date=27 October 2006|at=Main}}</ref>|Dicyan<ref Name="Pocket">{{cite book |title=NIOSH Pocket Guide to Chemical Hazards|date=September 2007 |publisher=Department of Health and Human Services, Centers for Disease Control, National Institute for Occupational Safety & Health |page=82}}</ref><ref name = "Merck">{{cite book |title=The Merck Index|url=https://archive.org/details/merckindexencycl00wind|url-access=registration|edition=10th|year=1983|publisher=Merck & Co. |location=Rahway, NJ|page=[https://archive.org/details/merckindexencycl00wind/page/385 385]|isbn=9780911910278}}</ref>|Carbon nitride<ref Name="Pocket" />|Oxalic acid dinitrile<ref name="Merck" />|Dicyanogen|Nitriloacetonitrile|CY}}
|Section1={{Chembox Identifiers
| CASNo = 460-19-5
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 534Q0F66RK
| PubChem = 9999
| ChemSpiderID = 9605
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| EINECS = 207-306-5
| UNNumber = 1026
| MeSHName = cyanogen
| ChEBI = 29308
| ChEBI_Ref = {{ebicite|correct|EBI}}
| RTECS = GT1925000
| Beilstein = 1732464
| Gmelin = 1090
| SMILES = N#CC#N
| StdInChI = 1S/C2N2/c3-1-2-4
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = JMANVNJQNLATNU-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
}}
|Section2={{Chembox Properties
| Formula = {{chem2|N\tC\sC\tN}}
| C=2 | N=2
| Appearance = Colourless gas
| Odor = pungent, [[Almond#Sweet and bitter almonds|bitter almond]]-like
| Density = 950 mg/mL (at −21&nbsp;°C)
| MeltingPtC = -28
| BoilingPtK = 252.0
| Solubility = 45 g/100 mL (at 20&nbsp;°C)
| SolubleOther = soluble in [[ethanol]], [[ethyl ether]]
| HenryConstant = 1.9 μmol/(Pa·kg)
| RefractIndex = 1.327 (18&nbsp;°C)
| VaporPressure = 5.1 atm (21&nbsp;°C)<ref name=PGCH/>
| MagSus = −21.6·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
|Section3={{Chembox Thermochemistry
| DeltaHf = 309.07 kJ/mol
| DeltaHc = −1.0978–−1.0942 MJ/mol
| Entropy = 241.57 J/(K·mol)
}}
|Section4={{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics1390.htm inchem.org]
| GHSPictograms = {{GHS02}}{{GHS06}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|220|331|410}}
| PPhrases = {{P-phrases|210|261|271|273|304+340|311|321|377|381|391|403|403+233|405|501}}
| NFPA-H = 4
| NFPA-F = 4
| NFPA-R = 2
| ExploLimits = 6.6–32%<ref name=PGCH/>
| PEL = none<ref name=PGCH>{{PGCH|0161}}</ref>
| IDLH = N.D.<ref name=PGCH/>
| REL = TWA 10 ppm (20 mg/m<sup>3</sup>)<ref name=PGCH/>
| MainHazards = forms [[cyanide]] in the body; flammable<ref name=PGCH/> 
}}
|Section5={{Chembox Related
| OtherFunction_label = alkanenitriles
| OtherFunction = {{ubl|[[Hydrogen cyanide]]|[[Thiocyanic acid]]|[[Cyanogen iodide]]|[[Cyanogen bromide]]|[[Cyanogen chloride]]|[[Cyanogen fluoride]]|[[Cyanogen azide]]|[[Acetonitrile]]|[[Aminoacetonitrile]]|[[Glycolonitrile]]|[[Propionitrile]]|[[Aminopropionitrile]]|[[Malononitrile]]|[[Pivalonitrile]]|[[Acetone cyanohydrin]]}}
| OtherCompounds = [[DBNPA]]
}}
}}
'''Cyanogen''' is the [[chemical compound]] with the [[chemical formula|formula]] {{chem2|(CN)2|auto=1}}. Its structure is {{chem2|N\tC\sC\tN}}. The simplest stable [[carbon nitride]], it is a [[Transparency and translucency|colorless]] and highly [[toxic]] [[gas]] with a [[pungency|pungent]] [[odor]]. The molecule is a [[pseudohalogen]]. Cyanogen molecules are [[linear molecular geometry|linear]], and consist of two CN groups ‒ analogous to diatomic halogen molecules, such as [[chlorine|Cl]]{{sub|2}}, but far less oxidizing. The two [[cyanide|cyano groups]] are bonded together at their [[carbon]] atoms, though other [[isomer]]s have been detected.<ref>{{cite journal |author1=Ringer, A. L. |author2=Sherrill, C. D. |author3=King, R. A. |author4=Crawford, T. D. | year = 2008 | title = Low-lying singlet excited states of isocyanogen | journal = International Journal of Quantum Chemistry | volume = 106 | issue = 6 | pages = 1137–1140 | doi = 10.1002/qua.21586 |bibcode = 2008IJQC..108.1137R}}</ref> The name is also used for the CN radical,<ref name=radical>{{cite book|doi=10.1007/978-3-642-11274-4_1806|chapter=Cyanogen Radical|title=Encyclopedia of Astrobiology|pages=402|year=2011|last1=Irvine|first1=William M.|isbn=978-3-642-11271-3}}</ref> and hence is used for compounds such as [[cyanogen bromide]] ({{chem2|Br\sC\tN}})<ref>{{OrgSynth |author=Hartman, W. W. |author2=Dreger, E. E. |title=Cyanogen Bromide |year=1931 |volume=11 |pages=30 |collvol=2 |collvolpages=150}}</ref> (but see also ''[[Cyano radical]]''). When burned at increased pressure with oxygen, it is possible to get a blue tinted flame, the temperature of which is about {{cvt|4800|C}} (a higher temperature is possible with ozone). It is as such regarded as the gas with the second highest temperature of burning (after [[dicyanoacetylene]]).

Cyanogen is the [[anhydride]] of [[oxamide]]:
:{{chem2|H2N\sC(\dO)\sC(\dO)\sNH2 → N\tC\sC\tN + 2 H2O}}

Oxamide is manufactured from cyanogen by hydration:<ref name=greenwood>{{Greenwood&Earnshaw2nd|pages=320–321}}</ref>

:{{chem2|N\tC\sC\tN + 2 H2O → H2N\sC(\dO)\sC(\dO)\sNH2}}

==Preparation==
Cyanogen is typically generated from [[cyanide]] compounds. One laboratory method entails thermal decomposition of [[mercury(II) cyanide|mercuric cyanide]]:
:{{chem2|2 Hg(CN)2 → (CN)2 + Hg2(CN)2}}
Or, one can combine solutions of copper(II) salts (such as [[copper(II) sulfate]]) with cyanides; an unstable copper(II) cyanide is formed which rapidly decomposes into [[copper(I) cyanide]] and cyanogen.<ref>{{cite journal | title = The Synthesis And Chemistry Of Cyanogen |author1=Brotherton, T. K. |author2=Lynn, J. W. | journal = [[Chemical Reviews]] | year = 1959 | volume = 59 | issue = 5 | pages = 841–883 | doi = 10.1021/cr50029a003}}</ref>
:{{chem2|2 CuSO4 + 4 [[Potassium cyanide|KCN]] → (CN)2 + 2 [[CuCN]] + 2 [[K2SO4]]}}

Industrially, it is created by the [[oxidation]] of [[hydrogen cyanide]], usually using [[chlorine]] over an activated [[silicon dioxide]] [[catalyst]] or [[nitrogen dioxide]] over a [[copper]] salt. It is also formed when [[nitrogen]] and [[acetylene]] are reacted by an electrical spark or discharge.<ref>{{cite journal |title=The Fixation of Atmospheric Nitrogen |author= Breneman, A. A. |journal=[[Journal of the American Chemical Society]] |volume=11 |issue=1 |pages=2–27 |date=January 1889 |doi=10.1021/ja02126a001|url= https://zenodo.org/record/1428969}}</ref>

==Reactions==
For the two less stable isomers of cyanogen, the order of the atoms differs. Isocyanogen (or cyanogen cyanide) is {{chem2|-C\tN+\sC\tN}}.<ref>{{cite journal |doi=10.1021/j100191a027 |title=Central Bond in the Three CN.cntdot.dimers NC-CN, CN-CN and CN-NC: Electron Pair Bonding and Pauli Repulsion Effects |date=1992 |last1=Bickelhaupt |first1=F. Matthias |last2=Nibbering |first2=Nico M. M. |last3=Van Wezenbeek |first3=Egbert M. |last4=Baerends |first4=Evert Jan |journal=The Journal of Physical Chemistry |volume=96 |issue=12 |pages=4864–4873}}</ref> It has been detected in the [[interstellar medium]].<ref>{{cite journal |doi=10.3847/2041-8213/aad089|doi-access=free |title=Discovery of Interstellar Isocyanogen (CNCN): Further Evidence that Dicyanopolyynes Are Abundant in Space |date=2018 |last1=Agúndez |first1=M. |last2=Marcelino |first2=N. |last3=Cernicharo |first3=J. |journal=The Astrophysical Journal Letters |volume=861 |issue=2 |pages=L22 |pmid=30186588 |pmc=6120679 |arxiv=1806.10328 |bibcode=2018ApJ...861L..22A}}</ref>

Addition of [[disulfur dichloride]] to cyanogen gives [[3,4-Dichloro-1,2,5-thiadiazole|3,4-dichloro-1,2,5-thiadiazole]].

==Paracyanogen==
[[File:Paracyanogen.png|thumb|left|class=skin-invert-image]] Paracyanogen is a [[polymer]] of cyanogen. It can be best prepared by heating [[mercury(II) cyanide]]. It can also be prepared by heating [[silver cyanide]], [[silver cyanate]], [[cyanogen iodide]] or cyanuric iodide.<ref>{{cite journal |last= Bircumshaw |first= L. L. |author2=F. M. Tayler |author3=D. H. Whiffen |year=1954 |title= Paracyanogen: its formation and properties. Part I| journal= J. Chem. Soc. |pages=931–935 |doi=10.1039/JR9540000931}}</ref> It can also be prepared by the polymerization of cyanogen at {{convert|300|to|500|C}} in the presence of trace impurities. Paracyanogen can also be converted back to cyanogen by heating to {{convert|800|C}}.<ref name=greenwood/> Based on experimental evidence, the structure of this polymeric material is thought to be rather irregular, with most of the [[carbon]] atoms being of [[Orbital hybridization#sp2|sp{{sup|2}} type]] and localized domains of [[Conjugated system|π conjugation]].<ref>{{cite journal|author=Maya, Leon|year=1993|journal=Journal of Polymer Science Part A|volume= 31|issue=10|pages= 2595–2600|title=Paracyanogen Reexamined |doi=10.1002/pola.1993.080311020 |bibcode=1993JPoSA..31.2595M |url=https://zenodo.org/record/1229357 |type=Submitted manuscript}}</ref>

==History==

Cyanogen was first synthesized in 1815 by [[Joseph Louis Gay-Lussac]], who determined its empirical formula and named it. Gay-Lussac coined the word "cyanogène" from the Greek words κυανός (kyanos, blue) and γεννάω (gennao, to create), because cyanide was first isolated by Swedish chemist [[Carl Wilhelm Scheele]] from the pigment [[Prussian blue]].<ref>{{cite journal | author = Gay-Lussac, J. L. | title = Recherches sur l'acide prussique | journal = Annales de Chimie | date = 1815 | volume = 95 | pages = 136–231 | url = https://books.google.com/books?id=m9s3AAAAMAAJ&pg=PA136 |language=fr}} Gay-Lussac names cyanogen on p. 163.</ref> It attained importance with the growth of the [[fertilizer]] industry in the late 19th century and remains an important intermediate in the production of many fertilizers. It is also used as a stabilizer in the production of [[nitrocellulose]].

Cyanogen is commonly found in [[comet]]s.<ref name="poison">{{cite web | title=Cometary Poison Gas Geyser Heralds Surprises | website=science.nasa.gov | date=2010-11-02 | url=https://science.nasa.gov/science-news/science-at-nasa/2010/02nov_epoxi2/ | archive-url=https://web.archive.org/web/20101106033738/https://science.nasa.gov/science-news/science-at-nasa/2010/02nov_epoxi2/ | archive-date=2010-11-06 | url-status=dead}}</ref> In 1910 a [[spectroscopic]] analysis of [[Halley's Comet]] found cyanogen in the comet's tail, which led to public fear that the Earth would be poisoned as it passed through the tail. People in [[New York City|New York]] wore gas masks, and merchants sold [[Quack (medicine)|quack]] "comet pills" claimed to neutralize poisoning.<ref name="poison" /> Because of the extremely diffuse nature of the tail, there was no effect when the planet passed through it.<ref>{{cite news |url=https://timesmachine.nytimes.com/timesmachine/1910/02/08/104920328.pdf |title=Comet's Poisonous Tail |newspaper=New York Times |date=1910-02-08}}</ref><ref>{{cite web | title=Halley's Comet 100 years ago | website=The Denver Post | date=2010-05-25 | url=https://www.denverpost.com/2010/05/25/halleys-comet-100-years-ago/}}</ref>

==Safety==
Like other [[cyanide]]s, cyanogen is very toxic, as it readily undergoes reduction to cyanide, which poisons the [[cytochrome c oxidase]] complex, thus interrupting the [[mitochondria]]l [[electron transfer chain]]. Cyanogen gas is an irritant to the eyes and respiratory system. Inhalation can lead to headache, dizziness, rapid pulse, nausea, vomiting, loss of consciousness, convulsions, and death, depending on exposure.<ref name="HitCL">{{cite book | editor = Muir, G. D. | year = 1971 | title = Hazards in the Chemical Laboratory | publisher = The Royal Institute of Chemistry | location = London}}</ref> Lethal dose through inhalation typically ranges from {{convert|100|to|150|mg|gr|abbr=off|lk=on}}.

Cyanogen produces the second-hottest-known natural flame (after [[dicyanoacetylene]] aka carbon subnitride) with a temperature of over {{convert|4525|C}} when it burns in oxygen.<ref>{{cite journal |author1=Thomas, N. |author2=Gaydon, A. G. |author3=Brewer, L. | title = Cyanogen Flames and the Dissociation Energy of N<sub>2</sub> | journal = The Journal of Chemical Physics | year = 1952 | volume = 20 | issue = 3 | pages = 369–374 | doi = 10.1063/1.1700426 | bibcode = 1952JChPh..20..369T}}</ref><ref>{{cite journal |author1=J. B. Conway |author2=R. H. Wilson Jr. |author3=A. V. Grosse |title=The Temperature of the Cyanogen-Oxygen Flame | journal = Journal of the American Chemical Society | year = 1953 | volume = 75 | issue = 2 | pages = 499 | doi = 10.1021/ja01098a517}}</ref>

==See also==
*[[Pseudohalogen]]

==References==
{{Reflist|30em}}

==External links==
* {{Commons category inline|Cyanogen}}
* {{Cite EB1911|wstitle=Cyanogen}}
* [https://web.archive.org/web/20060517035532/http://www.npi.gov.au/database/substance-info/profiles/29.html National Pollutant Inventory - Cyanide compounds fact sheet]
* [http://www.physorg.com/news147451495.html PhysOrg.com]
* [https://www.cdc.gov/niosh/npg/npgd0161.html CDC - NIOSH Pocket Guide to Chemical Hazards]

{{Chemical agents}}
{{Cyanides}}
{{Nitrogen compounds}}
{{Molecules detected in outer space}}
{{Authority control}}

[[Category:Alkanedinitriles]]
[[Category:Blood agents]]
[[Category:Lachrymatory agents]]
[[Category:Pseudohalogens]]