Editing Nerve agent (section)

===V-series===
[[File:VX-S-enantiomer-3D-balls.png|thumb|Chemical form of the nerve agent [[VX (nerve agent)|VX]].]]
[[File:Nerve agent V series.svg|thumb|400px|The V series of nerve agents.]]
The ''V-series'' is the second family of nerve agents and contains five well known members: [[VE (nerve agent)|VE]], [[VG (nerve agent)|VG]], [[VM (nerve agent)|VM]], [[VR (nerve agent)|VR]], and [[VX (nerve agent)|VX]], along with several more obscure analogues.<ref name='red":4"' />

The most studied agent in this family, [[VX (nerve agent)|VX]] (it is thought that the 'X' in its name comes from its overlapping isopropyl radicals), was invented in the 1950s at [[Porton Down]] in [[Wiltshire]], England. Ranajit Ghosh, a chemist at the Plant Protection Laboratories of [[Imperial Chemical Industries]] (ICI) was investigating a class of organophosphate compounds (organophosphate esters of substituted aminoethanethiols). Like Schrader, Ghosh found that they were quite effective pesticides. In 1953 and 1954, ICI conducted [[field trials]], intending to market the material as an [[acaricide]] with the common name [[VG (nerve agent)|amiton]]. Development was halted, as it was too toxic for safe use.<ref name=JH50>{{Cite book |last=Calderbank |first=Alan |title=Jealott's Hill: Fifty years of Agricultural Research 1928-1978 |publisher=Imperial Chemical Industries Ltd. |year=1978 |isbn=0901747017 |editor-last1=Peacock |editor-first=F.C. |pages=49–54 |url=https://archive.org/details/jealottshillfift0000peac/page/49 |chapter=Chapter 6: Organophosphorus Insecticides |url-access=registration}}</ref> The toxicity did not escape military notice and some of the more toxic materials had been sent to Porton Down for evaluation. After the evaluation was complete, several members of this class of compounds became a new group of nerve agents, the V agents (depending on the source, the V stands for Victory, Venomous, or Viscous). The best known of these is probably [[VX (nerve agent)|VX]], with [[VR (nerve agent)|VR]] ("Russian V-gas") coming a close second (amiton is largely forgotten as VG, with G probably coming from "G"hosh). All of the V-agents are persistent agents, meaning that these agents do not degrade or wash away easily and can therefore remain on clothes and other surfaces for long periods. In use, this allows the V-agents to be used to blanket terrain to guide or curtail the movement of enemy ground forces. The consistency of these agents is similar to oil; as a result, the contact hazard for V-agents is primarily – but not exclusively – dermal. VX was the only V-series agent that was fielded by the US as a munition, in rockets, [[artillery shell]]s, airplane spray tanks, and [[landmine]]s.<ref name="FM 3-8">''FM 3–8 Chemical Reference handbook''; US Army; 1967</ref><ref>[http://www.cma.army.mil/fndocumentviewer.aspx?docid=003677713 "U.S. Army Destroys Entire Stockpile of VX Spray Tanks"] {{webarchive|url=https://web.archive.org/web/20090206182557/http://www.cma.army.mil/fndocumentviewer.aspx?docid=003677713 |date=2009-02-06 }}, U.S. Army Chemical Materials Agency, December 26, 2007, accessed January 4, 2007</ref>

Analyzing the structure of thirteen V agents, the standard composition, which makes a compound enter this group, is the absence of [[Halide|halides]]. It is clear that many agricultural pesticides can be considered as V agents if they are notoriously toxic. The agent is not required to be a phosphonate and presents a dialkylaminoethyl group.<ref>{{cite report |first1=P. B. |last1=Coulter |first2=J. J. |last2=Callahan |first3=R.S. |last3=Link |work=U. S. Army Chemical Warfare Laboratories Technical Report |id={{DTIC|AD0314520}} |title=Physical Constants of Thirteen V Agents }}</ref> The toxicity requirement is waived as the VT agent and its salts (VT-1 and VT-2) are "non-toxic".{{sfn|Mager|1984|p=[{{GBurl|NsYdE70JxMkC|p=51}} 51]}} Replacing the sulfur atom with selenium increases the toxicity of the agent by orders of magnitude.{{sfn|Mager|1984|p=[{{GBurl|NsYdE70JxMkC|p=57}} 57]}}