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| Names | |
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| Preferred IUPAC name S-[2-(Diethylamino)ethyl]O-(2-methylpropyl) methylphosphonothioate | |
| Identifiers | |
3D model (JSmol) | |
| ChEBI | |
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| UNII | |
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| Properties | |
| C11H26NO2PS | |
| Molar mass | 267.368 g/mol |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
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VR (Russian VX,VXr,Soviet V-gas,GOSNIIOKhT substance No. 33,Agent "November") is a "V-series"unitarynerve agent closely related (it is anisomer) to the better-knownVX nerve agent.[1] It became a prototype for the series ofNovichok agents. According to chemical weapons expertJonathan Tucker, the first binary formulation developed under the Soviet Foliant program was used to makeSubstance 33, differing from VX only in the alkyl substituents on its nitrogen and oxygen atoms. "This weapon was given the code name Novichok."[2]
The development of VR started in 1957, after theSoviet Union obtained information about detection of high level of toxicity in phosphorylthiocholines[3] (the same yearLars-Erik Tammelin published his first articles on fluorophosphorylcholines and phosphorylthiocholines inActa Chemica Scandinavica) by a team from the Soviet Union's Scientific Research Institute No. 42 (NII-42). Sergei Zotovich Ivin, Leonid Soborovsky, and Iya Danilovna Shilakova jointly developed this analogue of VX. They completed their work in 1963 and were later awarded theLenin Prize for their achievement.[4] Abinary weapon comprising two less toxic precursors which mixed during flight to form Substance 33 was later developed by a team led by Nikolai Kuznetsov.[5]
In 1972 the Soviets openedCheboksary Khimprom, a manufacturing plant for VR inNovocheboksarsk.[6] All facilities inUSSR produced 15,557 tons of VR according to their declaration to theOrganisation for the Prohibition of Chemical Weapons (OPCW),[7] although most if not all of this has now been destroyed under disarmament treaties.[8]
VR has similar lethal dose levels to VX(10 – 50 mg), as well as being similar in appearance.[9] However, due to usage of diethylamino radicals instead of diisopropylamino it is more prone to decomposition. The former are worse at sterically protecting the nitrogen atom from attacking either phosphorus or the α-carbon atom adjacent to sulfur than the latter. According to UKDefence Science and Technology Laboratory Detection Department scientists Robin M. Black and John M. Harrison, chemical stability was an important factor why of all the similarly toxic phosphorylthiocholines, ethyl N-2-diisopropylaminoethyl methylphosphonothiolate in particular (now known as VX), was weaponized in the West.[10]
According to Russian CW developerVil Mirzayanov, in the late 1980s a group ofGosNIIOKhT chemists led by Georgiy Drozd prepared a scientific report that Substance 33 had much lower shelf life than VX. The report, writes Mirzayanov, caused 'panic' in the institute top management and the military representative office, and later was met with administrative resistance. This finding was independently verified by another chemist Igor Revelskiy but his report wasn't approved either.[11]
Following thepoisoning of Sergei and Yulia Skripal, former head of the GosNIIOKhT security department Nikolay Volodin said in an interview toNovaya Gazeta that Substance 33 was decomposing too quickly in combat conditions, and implied that this fact may have influenced the decision to continue research on theNovichok program.[12]
Both agents have similar symptoms and method of action to other nerve agents that act oncholinesterase, and treatment remains the same. However, the window for effectively treating second generation V seriesseizures is shorter, as they rapidly denature the acetylcholinesterase protein in a similar manner tosoman, making treatment with the standard nerve gas antidotepralidoxime ineffective unless it is given very soon after exposure.[citation needed] Pre-treatment withpyridostigmine prior to exposure, and treatment with other drugs such asatropine anddiazepam after exposure, will reduce symptoms of nerve agent toxicity but may not be sufficient to prevent death if a large dose of nerve agent has been absorbed. In addition to the standard seizures, some of the second generation V series agents are known to causecomas.
