Editing CR gas

{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 464184921
| Name = '''CR gas'''
| ImageFile = CR gas structure.svg
| ImageClass = skin-invert-image
| ImageFile2 = Dibenzoxazepine3D.png
| ImageClass2 = bg-transparent
| PIN = Dibenzo[''b'',''f''][1,4]oxazepine
|Section1={{Chembox Identifiers
| IUPHAR_ligand = 6472
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 8858
| InChI = 1/C13H9NO/c1-3-7-12-10(5-1)9-14-11-6-2-4-8-13(11)15-12/h1-9H
| InChIKey = NPUACKRELIJTFM-UHFFFAOYAI
| PubChem = 9213
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 1085100
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C13H9NO/c1-3-7-12-10(5-1)9-14-11-6-2-4-8-13(11)15-12/h1-9H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = NPUACKRELIJTFM-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 257-07-8
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = C1Q77A87V1
| SMILES = N\1=C\c3c(Oc2c/1cccc2)cccc3
}}
|Section2={{Chembox Properties
| C=13|H=9|N=1|O=1
| Density = 1.160±0.10 g/cm<sup>3</sup>
| MeltingPtC = 73
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'''CR''' gas or '''dibenzoxazepine''' (chemical name dibenz[''b'',''f''][1,4]oxazepine, is an [[incapacitating agent]] and a [[lachrymatory agent]]. CR was developed by the British [[Ministry of Defence (United Kingdom)|Ministry of Defence]] as a [[riot control agent]] in the late 1950s and early 1960s. A report from the [[Porton Down|Porton Down laboratories]] described exposure as "like being thrown blindfolded into a bed of [[stinging nettle]]s", and it earned the nickname "firegas".<ref name=":0">{{Cite journal|url = https://books.google.com/books?id=1HlXz0MRdsEC|title = The technology of riot control|last = Rosenhead|first = Jonathon|date = 23 Jul 1981|journal = New Scientist}}</ref><ref name=":1">{{Cite web|url = http://aei.pitt.edu/5538/|title = An Appraisal of Technologies of Political Control|date = 6 January 1998|access-date = 3 October 2015|via = pitt.edu|publisher = The STOA Programme, Directorate General for Research, European Parliament|last = Wright|first = Steve}}</ref>

In its effects, CR gas is very similar to [[CS gas]] (''o''-chlorobenzylidene malononitrile), but twice as potent, even though there is little structural resemblance between the two. For example, 2&nbsp;mg of dry CR causes skin redness in 10 min, 5&nbsp;mg causes burning and erythremia, and {{nowrap|20 mg{{px2}}{{mdash}}{{px2}}}}strong pain. Water usually amplifies the pain effect of CR on skin.  CR aerosols cause irritation at concentrations of 0.2&nbsp;[[Microgram|mcg]]/L, becoming intolerable at 3&nbsp;[[Microgram|mcg]]/L. The {{LD50}} of CR through air inhalation 350&nbsp;mg·min/L.<ref>Aleksandroc V.N., Emelyanov V.I. Poisonous Substances: textbook / G.A. Sokolskiy, ed. Moscow. 1990. — 272 с. ISBN 5-203-00341-6.</ref>

==Physical properties and deployment==
CR is a pale yellow crystalline solid with a spicy odor. It is slightly soluble in water and does not degrade in it. CR is usually presented as a microparticulate solid, in the form of [[suspension (chemistry)|suspension]] in a [[propylene glycol]]-based liquid. Contrary to its common name, it is not a gas but a solid at room temperature.

The dibenz[b,f][1,4]oxazepine [[Moiety (chemistry)|moiety]] is present in the [[typical antipsychotic]] [[drug]] [[loxapine]], but, unlike CR, [[loxapine]] is not reactive and is not an irritant. CR was first synthesised in 1962.<ref name="higginbo">{{cite journal| vauthors= Higginbo R, Suschitzky H |title=Synthesis of Heterocyclic Compounds. 2. Cyclisation of O-Nitrophenyl Oxygen Ethers|journal=[[J. Chem. Soc.]] |year=1962|pages=2367–2370| doi= 10.1039/jr9620002367}}</ref>

CR can be delivered either as an aerosol or a solution in water, making it able to be used in water cannons, smoke grenades, or handheld spray cans. For smoke it is usually fired in canisters (LACR) that heat up, producing an [[aerosol]] cloud at a steady rate.

==Effects==
CR gas is a [[lachrymatory agent]] (LA), exerting its effects through activation of the [[TRPA1]] channel.<ref name="pmid20806939">{{cite journal | vauthors = Gijsen HJ, Berthelot D, Zaja M, Brône B, Geuens I, Mercken M | title = Analogues of Morphanthridine and the Tear Gas Dibenz[b,f][1,4]oxazepine (CR) as Extremely Potent Activators of the Human Transient Receptor Potential Ankyrin 1 (TRPA1) Channel | journal = J Med Chem | volume = 53 | issue = 19 | pages = 7011–7020 |date=October 2010 | pmid = 20806939 | doi = 10.1021/jm100477n }}</ref><ref>{{cite journal | doi = 10.3390/molecules15129364| doi-access = free| title = Molecular Modeling Studies on 11H-Dibenz&#91;b,e&#93;azepine and Dibenz&#91;b,f&#93;&#91;1,4&#93;oxazepine Derivatives as Potent Agonists of the Human TRPA1 Receptor| date = 2010| last1 = Ai| first1 = Yong| last2 = Song| first2 = Fa-Jun| last3 = Wang| first3 = Shao-Teng| last4 = Sun| first4 = Qiang| last5 = Sun| first5 = Ping-Hua| journal = Molecules| volume = 15| issue = 12| pages = 9364–9379| pmid = 21169885| pmc = 6259276}}</ref><ref name="pmid19036859">{{cite journal | vauthors = Bessac BF, Sivula M, von Hehn CA, Caceres AI, Escalera J, Jordt SE | title = Transient receptor potential ankyrin 1 antagonists block the noxious effects of toxic industrial isocyanates and tear gases | journal = FASEB J | volume = 23 | issue = 4 | pages = 1102–1114 |date=April 2009 | pmid = 19036859 | doi = 10.1096/fj.08-117812 | doi-access = free | pmc = 2660642 }}</ref> Its effects are approximately 6 to 10 times more powerful than those of [[CS gas]]. CR causes intense skin irritation, in particular around moist areas; [[blepharospasm]], causing temporary blindness; and coughing, gasping for breath, and panic. It is capable of causing immediate incapacitation. It is a suspected [[carcinogen]]. It is toxic, but less so than CS gas, by ingestion and exposure. However, it can be lethal in large quantities. In a poorly ventilated space, an individual may inhale a lethal dose within minutes. Death is caused by [[asphyxiation]] and [[pulmonary edema]].

The effect of CR is long-term and persistent. CR can persist on surfaces, especially porous ones, for up to 60 days.

==Treatment==
While CS can be decontaminated with a large amount of water, use of water may exacerbate the effects of CR. Skin contaminated with CR gas may become extremely painful in contact with water for up to 48 hours after contamination.<ref name="higginbo" />

Medical treatment is mostly [[palliative]]. The contaminated clothing has to be removed. The eyes and skin can be washed, the eye pain can be alleviated with medications.<ref>{{cite web |url=http://www.zarc.com/english/tear_gases/crdibenzoxazepine.html |title=Tear Gases: CR - Dibenzoxazepine |publisher=Zarc International, Inc. |access-date=November 22, 2011 |archive-url=https://web.archive.org/web/20071221024545/http://www.zarc.com/english/tear_gases/crdibenzoxazepine.html |archive-date=December 21, 2007 |url-status=dead |df=mdy-all }}</ref>

==Use==
===Egypt===
During the [[2011 Egyptian revolution#November 2011 protests|2011 protests against the military government in Egypt]], Egyptian security forces allegedly used CR gas in addition to the more commonly used, less debilitating CS gas. One protester described the gas as making him feel "as if your eyes are about to fall out; then you have trouble breathing, and you lose your sight". Egyptians used yeast as a treatment for CR side effects on skin. [[Mohammed ElBaradei]] also confirmed via Twitter that "tear gas with [a] [[nerve agent]]" is being used in [[Tahrir Square]].<ref name="NRKmassakre">{{cite web | url=http://www.nrk.no/nyheter/verden/1.7887074 | title=Beskylder egyptiske styrker for massakre | publisher=NRK.no | access-date=November 22, 2011 | language=no}}</ref>

The only gas that has been identified by human rights organizations in protests "is CS tear gas, typically used by police forces to disperse crowds," stated Egyptian journalist Farida Helmy.<ref>Farida Helmy, "Chemical Combat", Egypt Today Magazine, January 2012 issue</ref> Egyptian use of CR gas has not been corroborated according to [[Human Rights Watch]].

===France===
People occupying an area in Notre-Dame-des-Landes against an airport project suspect the use of CR gas by French Police and Army in April 2018.<ref>{{Cite news|url=https://reporterre.net/Zad-de-Notre-Dame-des-Landes-ce-lundi-les-gendarmes-ont-demoli-la-charpente-du|title=Zad de Notre-Dame-des-Landes : ce lundi, les gendarmes ont démoli la charpente du Gourbi|work=Reporterre, le quotidien de l 'écologie|access-date=2018-04-16|language=fr}}</ref>

===Northern Ireland===
It started being available in police and army supplies, as a water cannon additive and as spray cans, in 1973 and was at least still so in 1981.<ref name=":0" /><ref name=":1" />

Republican groups in Northern Ireland have alleged that British Army and Royal Ulster Constabulary units used CR gas against Republican prisoners in the 1970s.<ref>[http://inac.org/action/alert/134 inac.org]  {{webarchive |url=https://web.archive.org/web/20080516084054/http://inac.org/action/alert/134 |date=May 16, 2008 }}</ref> Additionally, there are British military documents now declassified and in the public domain held in the records of the UK Ministry of Defence at the National Archives, London, that suggest that the British Army did deploy and use CR gas in Northern Ireland.
<ref>[http://discovery.nationalarchives.gov.uk/SearchUI/Details?uri=C11361813  TNA DEFE 13/1379 &nbsp;&nbsp;''"Northern Ireland: use of tear gases; use of CR gas for riot control in Northern Ireland, especially at HM Prison Maze; use of SPAD (Self Protection Aid Device) as a means of &nbsp;&nbsp;&nbsp;delivery. 1973."&nbsp;&nbsp;'']</ref>
<ref>[http://discovery.nationalarchives.gov.uk/SearchUI/Details?uri=C11067460  TNA DEFE 24/967&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;''"Northern Ireland: dibenzoxazepine (CR) gas; chemical agent for use in riot control. 1974-77."&nbsp;&nbsp;'']</ref>
<ref>[http://discovery.nationalarchives.gov.uk/SearchUI/Details?uri=C11206709  TNA DEFE 24/1090&nbsp;&nbsp;&nbsp;''"Northern Ireland: use of CS and CR gas in countering riots. 1969-77."&nbsp;&nbsp;'']</ref>
<ref>[http://discovery.nationalarchives.gov.uk/SearchUI/Details?uri=C11206686  TNA DEFE 24/1203&nbsp;&nbsp;&nbsp;''"Northern Ireland: terrorism; Operation PAGODA; use of CR gas (dibenzoxazepine). 1973-77."&nbsp;&nbsp;''] This document is still classified, although a record of it is listed in the National &nbsp;&nbsp;&nbsp;Archives (TNA) catalogue.</ref>
<ref>[http://discovery.nationalarchives.gov.uk/SearchUI/Details?uri=C11431904  TNA DEFE 24/1903&nbsp;&nbsp;&nbsp;''"Development of CR gas: introduction of Self Protection Aid Devices (SPAD) in Northern Ireland; includes arguments for and against their use. 1971-73."&nbsp;&nbsp;'']</ref>

===Philippines===
CR tear gas was used in suppression of the mutiny in Makati that was led by [[Antonio Trillanes|Sen. Antonio Trillanes]]. The tear gas was fired in the building and all the people in the building including reporters were affected.{{Citation needed|date=June 2013}}

===South Africa===
In the late 1980s, CR was used in the townships in [[South Africa]]. It caused some fatalities, in particular among children.<ref>{{cite journal| vauthors= Olajos EJ, Salem H |title=Riot Control Agents: Pharmacology, Toxicology, Biochemistry and Chemistry|journal=J Appl Toxicol |year=2001|pages=355–391| volume= 21| doi= 10.1002/jat.767| pmid= 11746179| issue= 5|s2cid=23368555|url=https://zenodo.org/record/1229208}}</ref><ref>{{cite web|url=http://www.ainfos.ca/04/oct/ainfos00066.html |title=Ireland, Organise! Press Release -Less Lethal Weapons Action Belfast |publisher=A-Infos |access-date=November 22, 2011}}</ref>

===Sri Lanka===
The Tamil Tigers of Sri Lanka, an insurgent group in Sri Lanka used CR gas against government forces that were on an offensive to flush and defeat these insurgents during September 2008. Its use hindered the army's progress but ultimately proved ineffective in preventing the army from overrunning their positions.
This is one of the first few cases of insurgents using CR gas as an [[Insurgency weapons and tactics|insurgent weapon]].{{Citation needed|date=June 2013}}

===Turkey===
In the [[2013 protests in Turkey|June 2013 protest]] against the Turkish government, Turkish police allegedly used CR gas on protesters in Istanbul. Doctors in a makeshift first aid post in a Mosque judged it as such.<ref>{{cite web | url=http://www.jewishpress.com/news/erdogans-police-may-be-using-chemical-cr-gas-on-protesters-video/2013/06/06/ | title=Erdogan's Police May Be Using Chemical CR Gas on Protesters | publisher=The Jewish Press | access-date=2013-09-02 | date=2013-06-05}}</ref><ref>{{cite web|url=https://www.youtube.com/watch?v=9b-_bzpd2Bs|title=Dolmabahçe Camii 03.06.2013 00:20|last=ahmet hasan|date=3 June 2013|via=YouTube}}</ref>

===Ukraine===
In Ukraine, CR gas was commonly used by special forces against demonstrators. Gas is packed in a form of spray cans "Cobra 1". For example, gas had been used on a demonstration dedicated to the Ukraine Independence Day (24 August 2011).<ref>{{cite web|url=http://tyzhden.ua/News/29429|title=Керівництву МВС показали, якими "засобами гігієни" воно озброює "Беркут" - Новини - Український тиждень, Тиждень.ua|date=26 August 2011 }}</ref> Also gas usage has been documented during demonstrations against Language Law Draft in Kyiv on 3 and 4 July 2012.<ref>{{cite web|url=http://www.pravda.com.ua/news/2012/07/4/6967998/|title="Беркут" відступив від Українського дому}}</ref>

==See also==
*[[CS gas]]
*[[Loxapine]]
*[[Pepper spray]] and [[Tear gas]]
*[[Resiniferatoxin]]

==References==
{{Reflist}}

{{Chemical warfare}}
{{Transient receptor potential channel modulators}}
{{Chemical classes of psychoactive drugs}}

[[Category:Lachrymatory agents]]
[[Category:Riot control agents]]
[[Category:Dibenzoxazepines]]