:Cyanogen

Cyanogen is typically generated from cyanide compounds. One laboratory method entails thermal decomposition of 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.{{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}}

:{{chem2|2 CuSO4 + 4 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.{{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}}

For the two less stable isomers of cyanogen, the order of the atoms differs. Isocyanogen (or cyanogen cyanide) is {{chem2|-C\tN+\sC\tN}}.{{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}} It has been detected in the interstellar medium.{{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}}

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

File:Paracyanogen.png 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.{{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}} 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}}. 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 and localized domains of π conjugation.{{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}}

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.{{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. 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 comets.{{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}} 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 wore gas masks, and merchants sold quack "comet pills" claimed to neutralize poisoning. Because of the extremely diffuse nature of the tail, there was no effect when the planet passed through it.{{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}}{{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/}}

Like other cyanides, cyanogen is very toxic, as it readily undergoes reduction to cyanide, which poisons the cytochrome c oxidase complex, thus interrupting the mitochondrial 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.{{cite book | editor = Muir, G. D. | year = 1971 | title = Hazards in the Chemical Laboratory | publisher = The Royal Institute of Chemistry | location = London}} 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.{{cite journal |author1=Thomas, N. |author2=Gaydon, A. G. |author3=Brewer, L. | title = Cyanogen Flames and the Dissociation Energy of N₂ | journal = The Journal of Chemical Physics | year = 1952 | volume = 20 | issue = 3 | pages = 369–374 | doi = 10.1063/1.1700426 | bibcode = 1952JChPh..20..369T}}{{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}}

In the Doctor Who serial "The Brain of Morbius" (the 5th serial of season 13), the Doctor synthesizes cyanogen using hydrogen cyanide as a starting material and vents it through a pipe to stop Solon from performing surgery on the brain of Morbius's body.

In Dragnet (1987) Friday (Dan Aykroyd) and Streebek (Tom Hanks) are tracking down the villain who stole "the pseudohalogenic compound cyanogen".{{cite web|url=https://getyarn.io/yarn-clip/f528f11d-6d18-4f71-b3e0-874f23325b97|title=The trichlornitromethane and the pseudo-halogenic compound cyanogen|access-date=August 18, 2021}}

In the second season of The Night Agent, cyanogen is stolen from a chemical plant as part of a plot to manufacture a chemical weapon.

• Pseudohalogen

{{Reflist|30em}}

• {{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}}

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Category:Alkanedinitriles

Category:Blood agents

Category:Lachrymatory agents

Category:Pseudohalogens