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Revision as of 13:36, 15 February 2012 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 474367622 of page VX_(nerve_agent) for the Chem/Drugbox validation project (updated: 'ChEBI').  Latest revision as of 01:21, 13 December 2024 edit 2400:417d:6ed5:e700:50b3:954e:349d:6d46 (talk)No edit summaryTags: Mobile edit Mobile web edit 
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{{short description|Chemical compound and chemical warfare nerve agent}}
{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}}
{{Distinguish|V-sub x}}
{{Use American English|date=May 2024}}
{{Use mdy dates|date=June 2024}}
{{Chembox {{Chembox
| Verifiedfields = changed | Verifiedfields = changed
| Watchedfields = changed | Watchedfields = changed
| Name = VX<ref name=Thiermann15/>
| verifiedrevid = 470627616
| verifiedrevid = 477002148
| ImageFile1 = VX-S-enantiomer-2D-skeletal.png
| ImageFile =
| ImageFile1_Ref = {{Chemboximage|correct|??}}
| ImageFile1 = VX-S-enantiomer-2D-skeletal.png
| ImageSize1=180px
| ImageFile1_Ref = {{Chemboximage|correct|??}}
| ImageName1 = Stereo structural formula VX ((S)-phosphinate)
| ImageName1 = Stereo structural formula VX ((S)-phosphinate)
| ImageFile2 = VX-S-enantiomer-3D-balls.png
| ImageCaption1 = '''''S''<sub>P</sub>-(−)-VX''' ]ace
| ImageFile2_Ref = {{Chemboximage|correct|??}}
| ImageFile2 = VX-S-enantiomer-3D-balls.png
| ImageSize2=180px
| ImageFile2_Ref = {{Chemboximage|correct|??}}
| ImageName2 = Ball and stick model of VX ((R)-phosphinate)
| ImageSize2 = 180px
| ImageFile3 = VX-S-enantiomer-3D-vdW.png
| ImageName2 = Ball and stick model of VX ((R)-phosphinate)
| ImageSize3=180px
| ImageCaption2 =
| IUPACName = Ethyl ({2-ethyl}sulfanyl)(methyl)phosphinate
| ImageFile3 = VX-S-enantiomer-3D-vdW.png
| SystematicName = Ethyl ({2-ethyl}sulfanyl)(methyl)phosphinate
| ImageSize3 = 180px
| OtherNames = -''O''-ethyl methylphosphonothioate<br />
| ImageCaption3 =
Ethyl {sulfanyl}(methyl)phosphinate
| PIN = ''S''-<nowiki/>{2-ethyl} ''O''-ethyl methylphosphonothioate
| Section1 = {{Chembox Identifiers
| OtherNames = -''O''-ethyl methylphosphonothioate<br />
| CASNo = 50782-69-9
Ethyl {sulfanyl}(methyl)phosphinate<br />Ethyl ''N''-2-diisopropylaminoethyl methylphosphonothiolate
| CASNo_Ref = {{cascite|correct|CAS}}
| Section1 = {{Chembox Identifiers
| CASNo1 = 51848-47-6
| CASNo = 50782-69-9
| CASNo1_Ref = {{cascite|changed|??}}
| CASNo_Ref = {{cascite|correct|CAS}}<ref name="Substance Name: VX">{{cite web|last1=Chambers|first1=Michael|title=Substance Name: VX|url=https://chem.nlm.nih.gov/chemidplus/rn/50782-69-9|website=ChemIDplus|publisher=U.S. National Library of Medicine, National Institutes of Health|access-date=February 24, 2017|language=en}}</ref>
| CASNo2 = 53800-40-1
| CASNo2_Ref = {{cascite|changed|??}} | UNII_Ref = {{fdacite|correct|FDA}}
| PubChem = 39793 | UNII = 9A4381183B
| PubChem = 39793
| PubChem_Ref = {{Pubchemcite|correct|PubChem}}
| ChemSpiderID = 36386 | ChemSpiderID = 36386
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| MeSHName = VX | MeSHName = VX
| ChEBI_Ref = {{ebicite|changed|EBI}} | ChEBI_Ref = {{ebicite|changed|EBI}}
| ChEBI= 136185
| ChEBI = <!-- blanked - oldvalue: 609247 -->
| ChEMBL = 483105 | ChEMBL = 483105
| ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL_Ref = {{ebicite|correct|EBI}}
| SMILES = CCOP(C)(=O)SCCN(C(C)C)C(C)C | SMILES = CCOP(C)(=O)SCCN(C(C)C)C(C)C
| SMILES1 = O=P(OCC)(SCCN(C(C)C)C(C)C)C | SMILES1 = O=P(OCC)(SCCN(C(C)C)C(C)C)C
| StdInChI = 1S/C11H26NO2PS/c1-7-14-15(6,13)16-9-8-12(10(2)3)11(4)5/h10-11H,7-9H2,1-6H3 | StdInChI = 1S/C11H26NO2PS/c1-7-14-15(6,13)16-9-8-12(10(2)3)11(4)5/h10-11H,7-9H2,1-6H3
| StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| InChI = 1/C11H26NO2PS/c1-7-14-15(6,13)16-9-8-12(10(2)3)11(4)5/h10-11H,7-9H2,1-6H3 | InChI = 1/C11H26NO2PS/c1-7-14-15(6,13)16-9-8-12(10(2)3)11(4)5/h10-11H,7-9H2,1-6H3
| StdInChIKey = JJIUCEJQJXNMHV-UHFFFAOYSA-N | StdInChIKey = JJIUCEJQJXNMHV-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| InChIKey = JJIUCEJQJXNMHV-UHFFFAOYAV}} | InChIKey = JJIUCEJQJXNMHV-UHFFFAOYAV}}
| Section2 = {{Chembox Properties | Section2 = {{Chembox Properties
| C=11 | H=26 | N=1 | O=2 | P=1 | S=1
| C = 11
| Density = 1.0083 g cm<sup>−3</sup>
| H = 26
| Appearance = amber liquid
| N = 1
| O = 2 | Odor = odorless
| P = 1 | MeltingPtC = −51
| S = 1 | BoilingPtC = 300
| VaporPressure = 0.09 Pa
| ExactMass = 267.142186283 g mol<sup>-1</sup>
| LogP = 2.047}}
| Density = 1.0083 g cm<sup>-3</sup>
| Section3 =
| MeltingPtC = -50
| Section4 =
| BoilingPtC = 298
| Section5 =
| VaporPressure = 0.09 Pa
| Section6 =
| LogP = 2.047}}
| Section7 = {{Chembox Hazards | Section7 = {{Chembox Hazards
| NFPA-H = 4 | NFPA-H = 4
| NFPA-F = 1 | NFPA-F = 1
| NFPA-R = 1 | NFPA-R = 1
| LD50 = 7 μg/kg (intravenous, rat)<ref name="Substance Name: VX"/>
| FlashPt = 159 °C<ref>{{cite web|url=http://www.ilpi.com/msds/vx.html |title=MSDS: Nerve Agent (VX) |accessdate=2007-10-25 |date=22 December 2000 |publisher=Edgewood Chemical Biological Center (ECBC), Department of the Army }}</ref>}}
| FlashPtC = 159
| FlashPt_ref =<ref>{{cite web|url=http://www.ilpi.com/msds/vx.html |title=Material Safety Data Sheet: Nerve Agent (VX) |access-date=October 25, 2007 |date=December 22, 2000|orig-year=1998 |website=ilpi.com|publisher=Interactive Learning Paradigms Incorporated}}</ref>}}
}} }}

{{Chemical agents sidebar |nerve}}

'''VX''' is an extremely toxic ] ] in the ] class, specifically, a ]. In the class of ]s, it was developed for military use in ] after ] of earlier discoveries of ] toxicity in ] research. In its pure form, VX is an oily, relatively ] liquid that is amber-like in colour.<ref>{{Cite web|url=https://emergency.cdc.gov/agent/vx/basics/facts.asp|title=CDC {{!}} Facts About VX|website=emergency.cdc.gov|publisher=Centers for Disease Control and Prevention|language=en-us|archive-url=https://web.archive.org/web/20180307120654/https://emergency.cdc.gov/agent/vx/basics/facts.asp|archive-date=March 7, 2018|url-status=live|access-date=March 20, 2018}}</ref> Because of its low volatility, VX persists in environments where it is dispersed.<ref name="FoAS"/><ref>{{Cite web |title=Nerve Agent VX {{!}} U.S. Army Chemical Materials Activity |url=https://www.cma.army.mil/nerve-agent-vx-fact-sheet/ |access-date=November 4, 2023 |language=en-US}}</ref>

VX, short for "venomous agent X",<ref>{{cite journal | journal = ] | volume = 94 | issue =38 | pages = 10–11 | date = September 26, 2016 | title = Detoxifying VX | doi=10.1021/cen-09438-scicon001| last1 = Bethany Halford }}</ref> is one of the best known of the V nerve agents and originated from pesticide development work at ] (ICI). It was developed further at ] in England during the early 1950s,<ref>{{Cite journal |last1=Worek |first1=Franz |last2=Thiermann |first2=Horst |last3=Wille |first3=Timo |date=2020 |title=Organophosphorus compounds and oximes: a critical review |journal=Archives of Toxicology |volume=94 |issue=7 |pages=2275–2292 |doi=10.1007/s00204-020-02797-0 |issn=0340-5761 |pmc=7367912 |pmid=32506210}}</ref> based on research first done by ], a chemist working for ] in Germany during the 1930s.{{citation needed|date=January 2024}} It is now one of a broader V-series of agents which are classified as ]s. VX has been allegedly used in warfare and has been used in several assassinations. The brother of North Korean leader ], ], had the substance ] in ] on February 13, 2017, by two women. He died while being rushed to hospital approximately 15 minutes later.

The substance is extremely deadly: VX fatalities occur with exposure to tens of milligram quantities via inhalation or absorption through skin. It is more potent than ], another nerve agent with a similar ]. On such exposure, these agents severely disrupt the body's signaling between the ] and ]s, leading to a prolonged ], ] of all the muscles in the body including the ], and death by ].<ref name="ke.army.mil">{{cite book |title=Medical Aspects of Chemical and Biological Warfare |chapter=Chapter 5: Nerve Agents |chapter-url=https://ke.army.mil/bordeninstitute/published_volumes/chemBio/Ch5.pdf |first1=Frederick R. |last1=Sidell |date=1997 |page=142ff}}</ref>

The danger of VX, in particular, lies in direct exposure to the chemical agent persisting where it was dispersed, and not through its evaporating and being distributed as a vapor; it is not considered a vapor hazard due to its relative ]. VX is considered an ] due to these physical and biochemical characteristics.<ref>{{cite book |title=Medical Aspects of Chemical and Biological Warfare |chapter=Chapter 4: The Chemical Warfare Threat and the Military Healthcare Provider |chapter-url=https://ke.army.mil/bordeninstitute/published_volumes/chemBio/Ch4.pdf |first1=Ernest T. |last1=Takafuji |first2=Allart B. |last2=Kok |date=1997 |page=123 |quote=Given favorable weather conditions, the use of persistent agents such as mustard and VX may pose a threat for many days. Such agents can deny or interfere with enemy occupation of terrain or use of equipment}}</ref> As a ], it is categorized as a ] by the ] and is banned by the ] of 1993,<ref>{{cite web | url = https://www.opcw.org/chemical-weapons-convention/annexes/annex-on-chemicals/schedule-1/ | title = Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction. Annex on Chemicals | publisher = United Nations Organisation for the Prohibition of Chemical Weapons}}</ref> where production and stockpiling of VX exceeding {{convert|100|g|oz |sigfig=3}} per year is outlawed. The only exception is for "research, medical or pharmaceutical purposes outside a single small-scale facility in aggregate quantities not exceeding {{cvt|10|kg|abbr=on}} per year per facility".<ref>{{cite web |title= Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction |url= https://www.opcw.org/fileadmin/OPCW/CWC/CWC_en.pdf |website= OPCW.org |publisher= Organization for the Prohibition of Chemical Weapons (OPCW) |author= OPCW |year=2005 |access-date= August 26, 2016 |page=122 |language= en}}</ref>
{{TOC limit|3}}

==Physical properties==
VX is an odorless and tasteless<ref>{{Cite web |date=May 16, 2019 |title=CDC {{!}} Facts About VX |url=https://emergency.cdc.gov/agent/vx/basics/facts.asp |access-date=April 27, 2022 |website=emergency.cdc.gov |language=en-us}}</ref><ref>{{Cite news |last=Doyle |first=Gerry |date=February 24, 2017 |title=What Is VX Nerve Agent? A Deadly Weapon, Rarely Seen |language=en-US |work=The New York Times |url=https://www.nytimes.com/2017/02/24/world/asia/vx-nerve-agent-kim-jong-nam.html |access-date=April 27, 2022 |issn=0362-4331}}</ref> chiral organophosphorous chemical with a molecular weight of 267.37 g/mol.<ref>{{Cite web |last=PubChem |title=O-Ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate |url=https://pubchem.ncbi.nlm.nih.gov/compound/39793 |access-date=April 27, 2022 |website=pubchem.ncbi.nlm.nih.gov |language=en}}</ref> Under standard conditions it is an amber-coloured liquid with a boiling point of {{convert|298|C|F}}, and a freezing point of {{convert|-51| C|F}}.<ref>{{Cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/39793#section=Melting-Point&fullscreen=true|title=Tx 60 {{!}} C11H26NO2PS |publisher=PubChem |language=en|access-date=April 13, 2017}}</ref> Its density is similar to that of water.<ref>{{Cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/39793#section=Density&fullscreen=true |title=Tx 60 {{!}} C11H26NO2PS |publisher=PubChem |language=en|access-date=April 13, 2017}}</ref> It has a ] value of 2.047, meaning it is relatively hydrophobic with about 100-fold more partitioning into octanol, over water.<ref>{{Cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/39793#section=Boiling-Point&fullscreen=true|title=Tx 60 {{!}} C11H26NO2PS |publisher=PubChem |language=en|access-date=April 13, 2017}}</ref> Its low ] of {{convert|0.09|Pa}} gives it a low volatility, resulting in a high persistence in the environment.<ref name = CroddyNTI02>{{cite news | author = Croddy, Eric | date = October 1, 2002 | title = Dusty Agents and the Iraqi Chemical Weapons Arsenal | work = Nuclear Threat Initiative | location = Washington, DC and Monterey, California | publisher = Middlebury Institute of International Studies, James Martin Center for Nonproliferation Studies | via = NTI.org | url=http://www.nti.org/analysis/articles/dusty-agents-iraqi-chemical-weapons/ | access-date = March 22, 2017}}</ref>

When weaponized, it can be dispersed as a liquid, aerosol or as a mixture with a ] or ] thickening agent.<ref name = CroddyNTI02/>

==Mechanism of action==
VX is an ].<ref name="McDowall">{{cite web|author=McDowall, Jennifer|title=Acetylcholine Recepetors|publisher=European Molecular Biology Laboratory/European Bioinformatics Institute|date=November 2005|url=https://www.ebi.ac.uk/interpro/potm/2005_11/Page1.htm}}</ref>
It blocks the function of the ] ] (AChE). Normally, when a ] is stimulated, it releases the neurotransmitter ] (ACh) into the space between the neuron and an adjacent muscle cell, the synaptic cleft. When acetylcholine binds to nicotinic receptors at the neuromuscular junction, it stimulates muscle contraction. To avoid a state of constant muscle contraction, the acetylcholine is then broken down (]) into the inactive substances ] and ] by AChE. VX blocks the action of AChE, resulting in an accumulation of acetylcholine in the space between the neuron and muscle cell. On a molecular level, this leads to the ongoing stimulation and eventual fatigue of all affected ] and ] ACh receptors. This results in initial violent contractions, followed by sustained supercontraction restricted to the fluid (]) of the subjunctional ] and prolonged, depolarizing ].<ref>{{cite web|url=https://apps.dtic.mil/sti/pdfs/ADA207033.pdf|archive-url=https://web.archive.org/web/20220412011450/https://apps.dtic.mil/sti/pdfs/ADA207033.pdf|url-status=live|archive-date=April 12, 2022|date=July 7, 1988|work= ] Department of Anatomy and Neurobiology|first1=John|last1=Rash|first2=Julie|last2=Elmund|title=Pathophsyiology of Anticholinesterase Agents}}</ref> The prolonged blockade results in flaccid paralysis of all the muscles in the body, and it is such sustained paralysis of the ] that causes death by ].<ref name="ke.army.mil"/>
Accumulation of acetylcholine in the brain also causes neuronal ], due to activation of ] receptors and ] release.<ref>{{cite journal| pmid=22498093 | doi=10.1016/j.neuro.2012.03.011 | volume=33 | issue=3 | title=Organophosphate-induced brain damage: mechanisms, neuropsychiatric and neurological consequences, and potential therapeutic strategies | year=2012 | author=Chen Y | journal=Neurotoxicology | pages=391–400}}</ref>

The extreme toxicity of VX is partly due to the fact that the inhibitor was designed to be an excellent structural mimic for the transition state of the natural substrate (acetylcholine) of acetylcholinesterase. VX has a very high "on-rate" to react with the target enzyme and form a stable P-O-C bond (phosphorylation).<ref name=pmid15366935>{{cite journal |doi=10.1021/bi0490946 |pmid=15366935 |title=Stereoselectivity toward VX is Determined by Interactions with Residues of the Acyl Pocket as Well as of the Peripheral Anionic Site of AChE† |journal=Biochemistry |volume=43 |issue=35 |pages=11255–65 |year=2004 |last1=Ordentlich |first1=Arie |last2=Barak |first2=Dov |last3=Sod-Moriah |first3=Gali |last4=Kaplan |first4=Dana |last5=Mizrahi |first5=Dana |last6=Segall |first6=Yoffi |last7=Kronman |first7=Chanoch |last8=Karton |first8=Yishai |last9=Lazar |first9=Arie |last10=Marcus |first10=Dino |last11=Velan |first11=Baruch |last12=Shafferman |first12=Avigdor |url=https://figshare.com/articles/journal_contribution/3325921 }}</ref> However, compared with other highly toxic nerve agents like ] or ], VX undergoes relatively slow "aging". Aging is a time-dependent side reaction (loss of an alkoxyl group) that occurs on nerve agents after phosphorylation and renders the nerve agent-acetylcholinesterase complex highly resistant to regeneration by any known antidote. Slower aging by VX suggests it should be possible to develop more effective antidotes and treatments.<ref name=pmid17370251>{{cite journal |doi=10.1002/jat.1241 |pmid=17370251 |title=Reactivation of organophosphate-inhibited human AChE by combinations of obidoxime and HI 6in vitro |journal=Journal of Applied Toxicology |volume=27 |issue=6 |pages=582–8 |year=2007 |last1=Worek |first1=F |last2=Aurbek |first2=N |last3=Thiermann |first3=H |s2cid=23783538 }}</ref>

The reaction products of acetylcholinesterase with VX before and after the "aging" reaction were solved in near atomic resolution by ] to aid in antidote development.<ref>{{cite journal |doi=10.1021/ja992704i |title=Reaction Products of Acetylcholinesterase and VX Reveal a Mobile Histidine in the Catalytic Triad |journal=Journal of the American Chemical Society |volume=121 |issue=42 |pages=9883–4 |year=1999 |last1=Millard |first1=Charles B |last2=Koellner |first2=Gertraud |last3=Ordentlich |first3=Arie |last4=Shafferman |first4=Avigdor |last5=Silman |first5=Israel |last6=Sussman |first6=Joel L }}</ref><ref name=pmid21454498>{{cite journal |doi=10.1074/jbc.M110.209569 |pmid=21454498 |pmc=3089521 |title=Structural Study of the Complex Stereoselectivity of Human Butyrylcholinesterase for the Neurotoxic V-agents |journal=Journal of Biological Chemistry |volume=286 |issue=19 |pages=16783–9 |year=2011 |last1=Wandhammer |first1=Marielle |last2=Carletti |first2=Eugénie |last3=Van Der Schans |first3=Marcel |last4=Gillon |first4=Emilie |last5=Nicolet |first5=Yvain |last6=Masson |first6=Patrick |last7=Goeldner |first7=Maurice |last8=Noort |first8=Daan |last9=Nachon |first9=Florian |doi-access=free }}</ref> The X-ray structures revealed the specific parts of the VX molecule that interact with key residues and sub-sites of the target enzyme. The structural kinetic of phosphorylation followed by aging also showed an unexpected conformational change in the catalytic triad suggestive of an "induced fit" between the VX molecule and acetylcholinesterase.

==Chemistry==
===Synthesis===
VX is ] at its ] atom. The individual ]s are identified as ''S''<sub>P</sub>-(−)-VX, and ''R''<sub>P</sub>-(+)-VX (where the "P" subscript highlights that the chirality is at phosphorus).<ref name=Thiermann15>{{cite book | author = John H, Balszuweit F, Kehe K, Worek F & Thiermann H | year = 2015 | chapter = Toxicokinetic Aspects of Nerve Agents and Vesicants | pages = 817–856, esp. 823 | title = Handbook of Toxicology of Chemical Warfare Agents | editor = Gupta, Ramesh C. | edition = 2nd | location = Cambridge, MA | publisher = Academic Press | isbn = 978-0128004944 | url = https://books.google.com/books?isbn=0128004940 | access-date = March 22, 2017 }}</ref>

VX is produced via the ], which gives a ] mixture of the two enantiomers. This entails a series of steps whereby ] is ] to produce ]. The resulting material is reacted with ] to form a ]. This is then ] with ] to produce ],
a mixed ]. Finally, this immediate precursor is reacted with ] to form VX.

]

VX can also be delivered in ] which mix in-flight to form the agent prior to release. Binary VX is referred to as VX2,<ref name=ellison>{{cite book | author = Ellison, D. Hank | title = Handbook of Chemical and Biological Agents | url = https://books.google.com/books?id=E58GAKMgcR4C&q=VX2+binary&pg=PA47 | publisher = CRC Press | location = New York | year = 2007 | page = 47 | isbn = 978-0-8493-1434-6 | access-date = February 21, 2014}}</ref> and is created by mixing QL with sulfur as is done in the ]. It may also be produced by mixing with sulfur compounds, as with the liquid dimethyl polysulfide mixture (known as NM) in the canceled ] program.{{cn|date=September 2023}}

===Solvolysis===
Like other ] nerve agents, VX may be destroyed by reaction with strong nucleophiles. The reaction of VX with concentrated aqueous ] results in two competing ] reactions: cleavage of either the P–O or P–S esters. Although the P–S cleavage is the dominant pathway, the product of P–O bond cleavage is the toxic phosphonic thioester ] and both reactions are slow.<ref name=YangACR1999>{{cite journal |first=Yu-Chu |last=Yang |title=Chemical Detoxification of Nerve Agent VX |journal=Acc. Chem. Res. |year=1999 |pages=109–15 |doi=10.1021/ar970154s |volume=32 |issue=2 }}</ref> In contrast, reaction with the ] anion (hydroperoxidolysis) leads to exclusive cleavage of the P–S bond and a more rapid overall reaction.<ref name=YangACR1999/><ref>{{cite journal|first1=Kelly |last1=Daniel |title=Computational studies on the solvolysis of the chemical warfare agent VX |journal=J. Phys. Org. Chem. |year=2008 |pages=321–28|doi=10.1002/poc.1333|last2=Kopff|first2=Laura A.|last3=Patterson|first3=Eric V.|volume=21|issue=4 |display-authors=etal}}</ref>

]
] product is still toxic)]]


{{further|Nerve agent#Biological effects}}

=== Symptoms of exposure ===
Early symptoms of skin contact include local sweating and muscular twitching at the area of exposure, followed by nausea or vomiting. Early symptoms of exposure to VX vapor include ] (runny nose) and tightness in the chest with shortness of breath (bronchial constriction). ] (pinpointing of the pupils) may be an early sign of agent exposure but is not usually used as the only indicator of exposure.<ref name=DAPAM385-61>{{cite web|url=http://www.army.mil/usapa/epubs/pdf/p385_61.pdf |archive-url=https://web.archive.org/web/20031224100600/http://www.army.mil/usapa/epubs/pdf/p385_61.pdf |url-status=dead |archive-date=December 24, 2003 |title=US Army Toxic Chemical Agent Safety Standards |access-date=December 15, 2007 |work=DA PAM 385-61. Section 7-8 Self/Buddy Aid Procedures |publisher=US Army }}</ref>

===Toxicology===
VX is extremely toxic. The potentially fatal dose is only slightly higher than the dose having any effect at all, and the effects of a fatal dose are so rapid that there is little time for treatment.<ref name="FoAS">{{cite web | author = FAS Staff | date = 2013 | title = Types of Chemical Weapons: Nerve Agents | location = Washington, D.C. | publisher = Federation of American Scientists | url=https://fas.org/programs/bio/chemweapons/cwagents.html | archive-url=https://web.archive.org/web/20161126174507/http://fas.org/programs/bio/chemweapons/cwagents.html|archive-date=November 26, 2016|url-status=live | access-date = March 22, 2017 }}</ref> The ] (LD<sub>50</sub>), the exposure required to kill half of a tested population, as estimated for 70&nbsp;kg human males via exposure to the skin is reported to be 5 to 10&nbsp;mg.

===Treatment===
When treating VX exposure, primary consideration is given to removal of the liquid agent from the skin, before removal of the individual to an uncontaminated area or atmosphere. After this, the victim is decontaminated by washing the contaminated areas with household bleach and flushing with clean water, followed by removal of contaminated clothing and further skin decontamination. When possible, decontamination is completed before the casualty is taken for further medical treatment.<ref>{{Cite web|url=https://emergency.cdc.gov/agent/vx/basics/facts.asp|title=CDC {{!}} Facts About VX|date=May 16, 2019|website=emergency.cdc.gov|language=en-us|access-date=December 22, 2019}}</ref><ref>{{Cite web|url=https://www.atsdr.cdc.gov/mmg/mmg.asp?id=523&tid=93|title=ATSDR - Medical Management Guidelines (MMGs): Nerve Agents (GA, GB, GD, VX)|website=www.atsdr.cdc.gov|access-date=December 22, 2019}}</ref><ref>{{Cite web|url=https://www.health.ny.gov/environmental/emergency/chemical_terrorism/nerve_agents_tech.htm|title=Facts About Nerve Agents|website=www.health.ny.gov|access-date=December 22, 2019}}</ref>

An individual known to have been exposed to a nerve agent, or who exhibits definite signs or symptoms of nerve-agent exposure is generally given the antidotes ] and ] (2-PAM), and in the case of convulsions an injected sedative or antiepileptic such as ].<ref name="vxtreatment">{{cite web |title=VX Recognition and Treatment |url=https://s3.amazonaws.com/PHR_other/PHR_VX_Fact_Sheet_04-13.pdf |publisher=Physicians for Human Rights |access-date=December 14, 2019}}</ref> In several nations the nerve agent antidotes are issued for military personnel in the form of an ] such as the United States military ].<ref name=DAPAM385-61/>

Atropine blocks a subset of acetylcholine receptors known as ]s (mAchRs), so that the buildup of acetylcholine produced by loss of the acetylcholinesterase function has a reduced effect on their target receptor.{{citation needed|date=March 2017}} 2-PAM reactivates the acetylcholinesterase enzyme (AChE), thus reversing the effects of VX.{{citation needed|date=March 2017}} VX and other organophosphates block AChE activity by binding to and ] the enzyme via transfer of the ] moiety from VX to the ] of AChE; this inactivates AChE and produces an inactive by-product from the remaining portion of the VX molecule.{{citation needed|date=March 2017}} Pralidoxime (2-PAM) removes this phosphate group.{{citation needed|date=March 2017}}

===Diagnostic tests===
]

Controlled studies in humans have shown that minimally toxic doses cause 70–75% depression of ] ] within several hours of exposure. The serum level of ] (EMPA), a VX hydrolysis product, was measured to confirm exposure in one poisoning victim. There also exist procedures for determination of VX hydrolysis products in urine and of VX adducts to albumin in blood.<ref>{{cite book | author = R. Baselt | title = Disposition of Toxic Drugs and Chemicals in Man | edition = 11th | publisher = Biomedical Publications | location = Seal Beach, CA | year = 2017 | pages = 2264–65}}</ref>

==History==
{{further|Nerve agent#History}}

===Discovery===
The chemists Ranajit Ghosh and J. F. Newman discovered the V-series nerve agents at the British firm ] in 1952, patenting diethyl ''S''-2-diethylaminoethyl phosphonothioate (]) in November 1952.{{Citation needed|date=February 2023}} Further commercial research on similar compounds ceased in 1955 when its lethality to humans was discovered. The U.S. started production of large amounts of VX in 1961 at ].{{Citation needed|date=February 2023}}

The discovery occurred when the chemists were investigating a class of ] compounds (organophosphate ] of substituted aminoethanethiols).<ref>{{cite journal|last=Ghosh|first=R.|author2=Newman, J.E. |title=A new group of organophosphorus pesticides|journal=Chemistry and Industry|date=January 29, 1955|page=118}}</ref> Like ], an earlier investigator of organophosphates, Ghosh found that they were quite effective ]s. In 1954, ICI put one of them on the market under the trade name '''Amiton'''. It was subsequently withdrawn, as it was too toxic for safe use. The toxicity did not go unnoticed, and samples of it were sent to the British government research facility at ] in ] for evaluation. After the evaluation was complete, several members of this class of compounds became a new group of nerve agents, the V agents. The best-known of these is probably VX, assigned the UK ] Purple Possum, with the ] (VR) coming a close second (Amiton is largely forgotten as VG). The name is a contraction of the words "venomous agent X".<ref>{{Citation|last=Usborne|first=Tim|title=Inside Porton Down: Britain's Secret Weapons Research Facility|date=June 28, 2016|url=https://www.imdb.com/title/tt5934096/|others=Michael Mosley, Jonathan Lyle, Rob Evans|access-date=March 20, 2018}}</ref>

Beginning in 1959, the United States Army began volunteer testing of VX in humans. Dr. Van M. Sim underwent an intravenous infusion of VX to evaluate its effects and to establish a baseline for future experimentation. After approximately 3.5 hours following initial administration of the agent, Sim suddenly became pale and delirious. The experiment was immediately terminated to preserve his life. In their conclusion, the researchers estimated that 2.12 μg/kg of VX delivered intravenously over the course of several hours would be the maximum tolerable dosage and that any more would risk death in a human subject.<ref>{{cite web|author=Kazuo K. Kimura, Bernard P. McNamara, Van M. Sim|url=https://apps.dtic.mil/sti/citations/AD1028432|archive-url=https://web.archive.org/web/20170326135945/http://www.dtic.mil/docs/citations/AD1028432|url-status=live|archive-date=March 26, 2017|title=Intravenous Administration of VX in Man|date=July 1, 1960|access-date=March 25, 2017}}</ref>

===Use as a weapon===
In 1988, a United Nations inquiry established that ] was responsible for deploying VX against Angolan insurgents during the ].<ref name="Hawk">{{cite book|last1=Hawk|first1=Kathleen Dupes|last2=Villella|first2=Ron|last3=Varona|first3=Adolfo Leyva de|title=Florida and the Mariel Boatlift of 1980: The First Twenty Days|url=https://books.google.com/books?id=DWbvAwAAQBAJ&pg=PA67|access-date=October 11, 2014|date=July 30, 2014|publisher=University of Alabama Press|isbn=978-0-8173-1837-6|page=250}}</ref><ref name="Hearing">{{cite report|author=<!--Staff writer(s); no by-line.-->|title=Cuba's Pursuit of Biological Weapons: Fact or Fiction? Hearing Before the Subcommittee on Western Hemisphere, Peace Corps, and Narcotics Affairs of the Committee of Foreign Relations, United States Senate, One hundredth and seventh Congress, Second Session, Jun5 5, 2002|year=2002|publisher=]|location=]|edition=First|url=https://fas.org/nuke/guide/cuba/sfrc060502.pdf|page=22|access-date=March 28, 2018|quote=Already in 1988, the United Nations Security Council has been informed of use of toxic weapons by Soviet-supported Cuba in Angola. Belgian toxicologists had certified that residue of chemical weapons—including sarin and VX gas—had been found in plants, water and soil where Cuban troops were alleged to have used chemicals against Savimbi's troops.}}</ref> UN toxicologists obtained trace elements of VX from soil, water, and plant samples taken from areas where Cuban troops had recently carried out counter-insurgency operations.<ref name="Hawk"/> Patients demonstrating symptoms of exposure to nerve agents first began appearing in Angolan hospitals around 1984.<ref name="Lewiston">{{cite news|title=Cubans using poison gas in Angola|url=https://news.google.com/newspapers?nid=1899&dat=19880826&id=qmMgAAAAIBAJ&pg=2776,3400252&hl=en|work=The Lewiston Journal|location=Lewiston–Auburn, Maine|date=August 26, 1988|access-date=July 28, 2015}}</ref>

There was evidence of a combination of chemical agents having been used by ] against the Kurds in the ] in 1988 under ], including VX.<ref>{{cite news|author = BBC | url=http://news.bbc.co.uk/onthisday/hi/dates/stories/march/16/newsid_4304000/4304853.stm |title=1988: Thousands die in Halabja gas attack | date= March 16, 1988 |access-date=March 1, 2012 }}</ref> Hussein later testified to ] that Iraq had researched VX but had failed to weaponize the agent due to production failure. After U.S. and allied forces invaded Iraq, no VX agent or production facilities were found. However, UNSCOM laboratories detected traces of VX on warhead remnants.<ref>{{cite web |author = CIA|url = https://www.cia.gov/library/reports/general-reports-1/gulfwar/cwagents/index.htm |archive-url = https://web.archive.org/web/20070613051218/https://www.cia.gov/library/reports/general-reports-1/gulfwar/cwagents/index.htm |url-status = dead |archive-date = June 13, 2007 | title= Intelligence Update: Chemical Warfare Agent Issues Chemical Warfare Issues During the Persian Gulf War | date = May 2, 2007 | access-date = October 22, 2012 }}</ref>

In December 1994 and January 1995, ] of ] synthesized {{convert|100|to|200|g |sigfig=2}} of VX which was used to attack three people. Two people were injured, and one 28-year-old man died, who was the first victim of VX ever documented in the world at that time. The VX victim, whom ] had suspected as a spy, was attacked at 7:00&nbsp;am on December 12, 1994, on the street in Osaka by ] and another AUM member, who sprinkled the nerve agent on his neck. He chased them for about 90 metres (100 yd) before collapsing, dying ten days later without ever coming out of a deep coma. Doctors in the hospital suspected at the time he had been poisoned with an organophosphate pesticide, but the cause of death was pinned down only after cult members arrested for the ] confessed to the killing. Metabolites of VX such as ethyl methylphosphonate, methylphosphonic acid and diisopropyl-2-(methylthio)ethylamine were later found in samples of the victim's blood seven months after his murder.<ref>Pamela Zurer. "Japanese cult used VX to slay member". ''Chemical and Engineering News''. 1998, Vol 76 (no. 35), 7.</ref> Unlike the cases for ] gas (the ] and ]), VX was not used for mass murder.

On February 13, 2017, ], half-brother of North Korean leader ], died after ] at ] in ]. According to the authorities he was murdered by poisoning with VX which was found on his face.<ref>{{Cite news|url=https://www.nytimes.com/2017/02/23/world/asia/kim-jong-nam-vx-nerve-agent-.html|title=Kim Jong-nam Was Killed by VX Nerve Agent, Malaysians Say|last1=Paddock|first1=Richard C.|date=February 23, 2017|newspaper=The New York Times|access-date=February 24, 2017|last2=Sang-hun|first2=Choe|issn=0362-4331}}</ref><ref>{{cite web|url=https://www.bbc.com/news/world-asia-39073389 |title=Kim Jong-nam killing: VX nerve agent 'found on his face' |work=] |date=February 24, 2017 |access-date=February 24, 2017}}</ref> The authorities further reported that one of the women suspected of applying the nerve agent experienced some physical symptoms of VX-poisoning.<ref>. ''The Star''. February 24, 2017. Retrieved February 23, 2017.</ref> The director of a non-] research program of the ] stated that VX fumes would have killed the suspected attackers even if they had been wearing gloves, suggesting that the VX was applied as ] that would mix to form VX only on the victim's face.<ref>{{cite news|first= Justin |last= McCurry |url=https://www.theguardian.com/world/2017/feb/24/what-is-vx-nerve-agent-killed-kim-jong-nam-north-korea |title=What is the VX nerve agent that killed North Korean Kim Jong-nam? |work= ] |date=February 20, 2017 |access-date=February 25, 2017}}</ref>

===Worldwide stockpiles===
Some countries known to possess VX are the United States, Russia,<ref name=autogenerated1>{{cite web |url=http://www.cfr.org/publication/9556/ |title=VX |access-date=June 12, 2007 |publisher=] |archive-url=https://web.archive.org/web/20090131063113/http://www.cfr.org/publication/9556 |archive-date=January 31, 2009 |url-status=dead }}</ref> North Korea,<ref>{{Cite news|url=https://www.usatoday.com/story/news/world/2018/03/07/u-s-north-korea-used-chemical-agent-vx-kill-kim-jong-uns-half-brother/402478002/|title=U.S. says North Korea used nerve agent VX to assassinate Kim Jong Un's half-brother|first=Jane|last=Onyanga-Omara|work=]}}</ref> and Syria.<ref>{{cite web|url=http://www.diplomatie.gouv.fr/IMG/pdf/Syrie_Synthese_nationale_de_renseignement_declassifie_le_02_09_2013_cle01b7e8.pdf |title=Synthèse nationale de renseignement déclassifié |trans-title=National synthesis of declassified intelligence |language=fr |date=August 21, 2013 |access-date=December 1, 2017}}</ref> A ]ese pharmaceutical facility, the ], was bombed by the U.S. in 1998 acting on information that it produced VX and that the origin of the agent was associated with both Iraq and ].{{cn|date=September 2023}} The U.S. had obtained soil samples identified as containing ] (EMPTA), a chemical used in the production of VX which may also have commercial applications. Chemical weapons experts later suggested that the widely used ] organophosphate insecticide could have been mistaken for EMPTA.<ref>{{cite book | title = Weapons of mass destruction: an encyclopedia of worldwide policy, technology, and history | isbn = 1-85109-490-3 | year = 2005 |editor1=Eric Croddy |editor2=James J. Wirtz | chapter = EMPTA (O-Ethyl methylphosphonothioic acid) | author = Claudine McCarthy | pages = 123–24 | publisher = Bloomsbury Academic | chapter-url = https://books.google.com/books?id=ZzlNgS70OHAC&pg=PA123 | chapter-format = ] excerpt | access-date = February 21, 2014}}</ref> Cuba obtained VX during the 1980s and deployed it during its ].<ref name="Hawk"/>

In 1969, the U.S. government cancelled its chemical weapons programs, banned the production of VX in the United States, and began the destruction of its stockpiles of agents by a variety of methods. Early disposal included the U.S. Army's ] (Cut Holes And Sink 'Em) program, in which old ships were filled with chemical weapons stockpiles and then ]. CHASE 8 was conducted on June 15, 1967, in which the steamship ''Cpl. Eric G. Gibson'' was filled with 7,380 VX rockets and scuttled in {{convert|7200|ft|m|abbr=on|order=flip}} of water off the coast of ]. ] was used for VX stockpile destruction starting in 1990 with ] in the North Pacific with other incineration plants following at ], ], ] and ] with the last of the VX inventory destroyed on December 24, 2008.<ref>{{cite web|url=http://www.cma.army.mil/endofvx.aspx|archive-url=https://web.archive.org/web/20090327045904/http://www.cma.army.mil/endofvx.aspx|archive-date=March 27, 2009|title=VX Destruction Milestone|date=March 20, 2009|publisher=U.S. Army Chemical Materials Agency}}</ref>

====Stockpile elimination====
Worldwide, VX disposal has continued since 1997 under the mandate of the ]. When the convention entered force, the parties declared worldwide stockpiles of {{convert|19586|t|ST}} of VX. As of December 2015, 98% of the stockpiles had been destroyed.<ref>{{cite report | publisher = Organisation for the Prohibition of Chemical Weapons | date = November 30, 2016 | title = Report of the OPCW on the Implementation of the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction in 2015 | chapter-url = https://www.opcw.org/documents-reports/annual-reports/ | chapter = Annex 3 | page = 42 | access-date = March 8, 2017}}</ref>

In fiscal year 2008, the ] released a study finding that the United States had dumped at least {{convert|124|ST|order=flip}} of VX into the Atlantic Ocean off the coasts of New York/New Jersey and Florida between 1969 and 1970. This material consisted of nearly 22,000 ]s, 19 bulk containers holding {{convert|1400|lb|abbr=on|order=flip}} each, and one ].<ref>{{cite web | url = https://www.denix.osd.mil/portal/page/portal/denix/environment/ARC/FY2008DEP/29_FY08DEPARC_App_Q_Sea_Disposal_final.pdf | title = App_Q_Sea_Disposal_final |publisher = denix.osd.mil | access-date = September 7, 2009}}</ref>

The ] began VX stockpile elimination using chemical neutralization in 2005. VX was hydrolyzed to much less toxic byproducts by using concentrated caustic solution, and the resulting waste was then shipped off-site for further processing. Technical and political issues regarding this secondary byproduct resulted in delays, but the depot completed their VX stockpile destruction in August 2008.<ref>{{cite web | url = http://www.cma.army.mil/fndocumentviewer.aspx?docid=003678571 | title = Depot Confirms VX Stockpile Eliminated | publisher = ] | access-date = January 7, 2013}}</ref>

The remaining VX stockpile in the U.S. was treated by the ] in Kentucky, part of the ] program. The program was established as an alternative to the incineration process successfully used by the ], which completed its stockpile destruction activities in March 2012. The Blue Grass Pilot Plant has been plagued by repeated cost over-runs and schedule slippages since its inception.<ref>{{cite news|first=Chris|last = Schneidmiller| url=http://www.nti.org/gsn/article/us-chemical-weapons-disposal-slippage-no-surprise-expert-says/ |title=U.S. Chemical Weapons Disposal Slippage "No Surprise," Expert Says | newspaper =]| date= April 18, 2001 |access-date=October 11, 2012}}</ref>

In Russia, the U.S. provided support for these destruction activities with the ].<ref>{{cite web|url=http://www.dtra.mil/missions/NunLugar/NunLugarHome.aspx|title=Nunn-Lugar Global Cooperation Initiative |publisher=] and ]|access-date=May 23, 2012}}</ref> The Initiative has been able to convert a former chemical weapons depot at ], ] into a facility to destroy those chemical weapons. The new facility, which opened in May 2009, has been working on eliminating the nearly {{convert|5950|ST|order=flip}} of nerve agents held at the former storage complex. However, this facility only held about 14% of ], which were stored at seven sites.<ref>{{cite news| url= https://www.nytimes.com/2009/05/27/world/europe/27russia.html?ref=world | work=] | title=In Siberia, the Death Knell of a Complex Holding a Deadly Stockpile | first=Clifford J. | last=Levy | date=May 27, 2009 | access-date=April 9, 2010}}</ref>

==In popular culture==
One of the best-known references to VX in popular culture is its use in the 1996 film '']'',<ref>{{cite web|publisher=]|date=January 31, 2012|url=http://www.rsc.org/chemistryworld/News/2012/January/decontaminating-toxic-nerve-agents.asp|title=Molecular dynamics to combat chemical terrorism|work=Chemistry World}}</ref><ref>{{cite news|first=Ilan Ben|last=Zion|newspaper=]|date=August 29, 2013|url=http://www.timesofisrael.com/gas-mask-kits-contain-no-antidote-for-nerve-gas/|title=Vital sarin antidote missing from gas mask kits}}</ref> which centers on a threatened VX attack on ] from the island of ]. The film uses ], notably with VX being ascribed corrosive powers it does not possess, permitting an early scene in which a VX victim is shown with his face melting, rather than dying through asphyxiation.

Other references to VX are found in the 2012 film '']'' in which it is revealed that a nearby ] attack was a VX attack, prompting the four couples to contemplate a suicide pact, as well as the 2015 film '']'', in which series protagonist ] steals VX nerve gas from ] on their way to Syria. Also season 5 of the TV series '']'', has a similar storyline.<ref>, January 30, 2006.</ref> The fifth episode of the 2020 anime series '']'' features a tear gas bomb with canisters loaded with VX gas and placed inside a cabinet of a ] within the embassy; the protagonist Daisuke Kambe and two other characters were trapped inside the room after relocating themselves due to security reasons, and figuring out how to escape before the bomb detonates.

The album '']'' by the ] band ] contains a song about ] called "VX Gas Attack".

In the ] show '']'', series 2 episode 5, a dirty bomb using VX is said to have gone off in a "training exercise". Artistic license is also used in this story, as VX is described as a gas, with "chlorine bonding" making it "almost indestructible." An incorrect formula is given, showing a diester rather than a thioester.

In the video game '']'', VX is alluded to as a nerve agent used by the government to contain a pattern which infects and kills humans and other animals.

In the book ''Nightshade'', the twelfth book in the ] Series, VX plays a major role, as it is used by terrorists in an attempt to kill over half of the British government.

In the book ''Ice Cold'', the eighth Rizzoli and Isles novel by ], VX gas is featured and responsible for many deaths.

The second episode of the TV series '']'' (season 1) focuses on a chemical weapons lab in an abandoned hospital, producing VX gas.

In the ] show '']'', agent Hannah Wells is killed by VX in season 3, episode 7.

In the ] show '']'', season 2 episode 9, a VX canister is the main plot point.

In the 2003 video game '']'', the acquisition of VX by terrorists is a major plot point in both versions of the game.

In the ] show '']'', American soldiers discover a computer used by apparent terrorists in ]. "VX components" are displayed as an item for purchase on the computer, which is logged into Araknet, a ] created by the protagonists of the series.

Metal Gear includes references to VX nerve gas in its plotlines, often as a lethal chemical threat within its espionage and warfare scenarios.

==See also==
{{Div col|colwidth=30em}}
* ]
* ]
* ]
* ]
* ]
{{Div col end}}

==References==
{{reflist|30em}}

==External links==
{{Commons category}}
* at Molecules of the Month, Chemistry IT Centre of the University of Oxford
* —Terrorism: Questions & Answers, Council on Foreign Relations
*
*
* at CBWInfo
* – Article from ''The New York Times''

{{Chemical warfare}}
{{Acetylcholine metabolism and transport modulators}}
{{Neurotoxins}}
{{U.S. chemical weapons}}
{{Authority control}}

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