VR (Russian VX, VXr, Soviet V-gas, GOSNIIOKhT substance No. 33, Agent "November") is a "V-series" unitary nerve agent closely related (it is an isomer) to the better-known VX nerve agent. It became a prototype for the series of Novichok agents. According to chemical weapons expert Jonathan Tucker, the first binary formulation developed under the Soviet Foliant program was used to make Substance 33, differing from VX only in the alkyl substituents on its nitrogen and oxygen atoms. "This weapon was given the code name Novichok." History The development of VR started in 1957, after the Soviet Union obtained information about detection of high level of toxicity in phosphorylthiocholines (the same year Lars-Erik Tammelin published his first articles on fluorophosphorylcholines and phosphorylthiocholines in Acta 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 the Lenin Prize for their achievement. A binary weapon comprising two less toxic precursors which mixed during flight to form Substance 33 was later developed by a team led by Nikolai Kuznetsov, for which they were awarded the 1990 Lenin Prize. In 1972 the Soviets opened Cheboksary Khimprom, a manufacturing plant for VR in Novocheboksarsk. All facilities in USSR produced 15,557 tons of VR according to their declaration to the Organisation for the Prohibition of Chemical Weapons (OPCW), although most if not all of this has now been destroyed under disarmament treaties. Comparison to VX VR has similar lethal dose levels to VX (between 10–50 mg), as well as being similar in appearance. 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 UK Defence 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. According to Russian CW developer Vil Mirzayanov, in the late 1980s a group of GosNIIOKhT chemists led by Georgiy Drozd prepared a scientific report that Substance 33 had much lower shelf life than VX. The report, writes Mirzayanov, caused