{{Short description|Chemical compound (nerve agent)}} {{Use mdy dates|date=March 2012}} {{morefootnotes|date=September 2017}} {{About|the nerve agent|the tuberculosis medicine|Cycloserine}} {{chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 434818651 | ImageFileL1 = Cyclosarin.svg | ImageClassL1 = skin-invert-image | ImageFileR1 = Cyclosarin-3D-balls.png | ImageClassR1 = bg-transparent | PIN = Cyclohexyl methylphosphonofluoridate | OtherNames = GF;(Fluoro-methyl-phosphoryl)oxycyclohexane |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 58069 | InChI = 1/C7H14FO2P/c1-11(8,9)10-7-5-3-2-4-6-7/h7H,2-6H2,1H3 | InChIKey = SNTRKUOVAPUGAY-UHFFFAOYAC | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C7H14FO2P/c1-11(8,9)10-7-5-3-2-4-6-7/h7H,2-6H2,1H3 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = SNTRKUOVAPUGAY-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 329-99-7 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = VM36F9N236 | PubChem = 64505 | UNNumber = 2810 | SMILES = O=P(F)(OC1CCCCC1)C }} |Section2={{Chembox Properties | C=7 | H=14 | F=1 | O=2 | P=1 | Appearance = Colorless liquid | Density = 1.1278 g/cm<sup>3</sup> | MeltingPtC = -30 | BoilingPtC = 239 | Solubility = Almost insoluble}} |Section3={{Chembox Hazards | MainHazards = | FlashPtC = 94 | AutoignitionPtC = }} }}

'''Cyclosarin''' or '''GF''' (cyclohexyl methylphosphonofluoridate) is an extremely toxic substance used as a chemical weapon.<ref>Ellison, D. Hank (2008), Handbook of Chemical and Biological Warfare Agents (Second ed.), CRC Press, pp 20-21. {{ISBN|978-0-849-31434-6}}</ref> It is a member of the ''G-series'' family of nerve agents, a group of chemical weapons discovered and synthesized by a German team led by Gerhard Schrader. The major nerve gases are the G agents, sarin (GB), soman (GD), tabun (GA), and the V agents such as VX. The original agent, tabun, was discovered in Germany in 1936 in the process of work on organophosphorus insecticides. Next came sarin, soman and finally, cyclosarin, a product of commercial insecticide laboratories prior to World War II.

As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations. Pursuant to UN Resolution 687 its production and stockpiling was outlawed globally by the Chemical Weapons Convention (CWC) of 1993, although Egypt, Israel, North Korea and South Sudan have not ratified the CWC (thus not outlawing their own stockpiling of chemical weapons).

==Chemical characteristics== Like its predecessor sarin, cyclosarin is a liquid organophosphate nerve agent. Its physical characteristics are, however, quite different from those of sarin.

At room temperature, cyclosarin is a colorless liquid whose odor has been variously described as sweet and musty,<ref>Ledgard J. A laboratory history of chemical warfare agents (2nd, 2006). pp 197-202. {{ISBN|978-0-6151-3645-5}}</ref> or resembling peaches or shellac. Unlike sarin, cyclosarin is a ''persistent'' liquid, meaning that it has a low vapor pressure and therefore evaporates relatively slowly, at only about 1/69th the rate of sarin and 1/20th that of water.

Also unlike sarin, cyclosarin is flammable, with a flash point of 94&nbsp;°C (201&nbsp;°F).

==History== First synthesized during World War II as part of Nazi Germany's chemical weapons research on organophosphate compounds after their military potential was recognized, cyclosarin was also studied later in the United States and Great Britain in the early 1950s as part of a systematic study of potential nerve agents. It was never selected for mass production, however, due to its precursors being more expensive than those of other G-series nerve agents such as sarin (GB).

To date, Iraq is the only nation known to have manufactured significant quantities of cyclosarin for use as a chemical agent and to deploy it in battle. During the Iran–Iraq War (1980–1988), the Iraqis used sarin and cyclosarin together as a mixture. This was likely done to obtain a more persistent chemical agent as well as in response to an existing embargo placed on alcohol precursors for sarin.<ref>{{cite web|url=http://www.cbwinfo.com/Chemical/Nerve/GF.shtml|title=Nerve Agent:GF|access-date=January 5, 2009|archive-url=https://web.archive.org/web/20090108001218/http://www.cbwinfo.com/Chemical/Nerve/GF.shtml|archive-date=January 8, 2009|url-status=dead}}</ref>

==Munitions== ===Binary weapons=== {{More citations needed section|date=July 2022}} Like other nerve agents, cyclosarin can be shipped in binary munitions.

A cyclosarin binary weapon would most likely contain methylphosphonyl difluoride in one capsule, with the other capsule containing a mixture of cyclohexylamine and cyclohexanol.

===GB-GF mixtures=== Iraq fielded munitions filled with a mixture of GB (sarin) and GF (cyclosarin). Tests on mice indicated that GB-GF mixtures have a relative toxicity between GF and GB.<ref>{{cite web|url=http://www.cbwinfo.com/Chemical/Nerve/GF.shtml|title=CBWInfo.com|access-date=March 1, 2012|archive-url=https://web.archive.org/web/20090108001218/http://www.cbwinfo.com/Chemical/Nerve/GF.shtml|archive-date=January 8, 2009|url-status=dead}}</ref>

==References== {{Reflist}} * United States Central Intelligence Agency. (July 15, 1996). [http://www.fas.org/irp/gulf/cia/960715/72569.htm Stability of Iraq's Chemical Weapon Stockpile] {{Webarchive|url=https://web.archive.org/web/20110428103309/http://www.fas.org/irp/gulf/cia/960715/72569.htm |date=April 28, 2011 }} Retrieved October 30, 2004 * Office of the Special Assistant for Gulf War Illnesses. (Oct. 19, 2004). [http://www.gulflink.osd.mil/khamisiyah_tech/kham_tech_tabbi.htm Chemical Properties of Sarin and Cyclosarin] {{Webarchive|url=https://web.archive.org/web/20171014001812/http://www.gulflink.osd.mil/khamisiyah_tech/kham_tech_tabbi.htm |date=October 14, 2017 }} Retrieved October 30, 2004 * [http://www.globalsecurity.org/military/library/news/2004/07/mil-040702-centcom01.htm Press release from Centcom] confirming that the chemical munitions found by the Poles dated back to before the 1991 Gulf War, and, thus, could not represent a threat.

{{Chemical warfare}} {{Acetylcholine metabolism and transport modulators}}

Category:Acetylcholinesterase inhibitors Category:Methylphosphonofluoridates Category:G-series nerve agents Category:German inventions of the Nazi period Category:Highly-toxic chemical substances Category:Cyclohexyl compounds