A-234 is an

organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered a ...

nerve agent Nerve agents, sometimes also called nerve gases, are a class of organic chemicals that disrupt the mechanisms by which nerves transfer messages to organs. The disruption is caused by the blocking of acetylcholinesterase (AChE), an enzyme that ...

. It was developed in the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...

under the FOLIANT program and is one of the group of compounds referred to as

Novichok agent Novichok (russian: Новичо́к, lit=newcomer, novice, newbie) is a group of nerve agents, some of which are binary chemical weapons. The agents were developed at the GosNIIOKhT state chemical research institute by the Soviet Union and R ...

s that were revealed by

Vil Mirzayanov Vil Sultanovich Mirzayanov (russian: Вил Султанович Мирзаянов, tt-Cyrl, Вил Солтан улы Мирзаҗанов; born 9 March 1935 in Starokangyshevo, Dyurtyulinsky District, Bashkortostan) is a Russian people, Russi ...

. In March 2018 the Russian ambassador to the UK, Alexander Yakovenko, claimed to have been informed by British authorities that A-234 had been identified as the agent used in the

poisoning of Sergei and Yulia Skripal On 4 March 2018, Sergei Skripal, a former Russian military officer and double agent for the British intelligence agencies, and his daughter, Yulia Skripal, were poisoned in the city of Salisbury, England. According to UK sources and the Organi ...

. Vladimir Uglev, one of the inventors of the Novichok series of compounds, said he was "99 percent sure that it was A-234" in relation to the 2018 Amesbury poisonings, noting its unusually high persistence in the environment. According to a classified report by the

United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

National Ground Intelligence Center The National Ground Intelligence Center (NGIC) is part of the United States Army Intelligence and Security Command. The NGIC provides scientific and technical intelligence (S&T) and general military intelligence (GMI) on foreign ground forces i ...

, the agent designated as

A-232 A-232 is an organophosphate nerve agent. It was developed in the Soviet Union under the FOLIANT program and is one of the group of compounds referred to as Novichok agents that were revealed by Vil Mirzayanov. A-232 is reportedly slightly less pot ...

and its ethyl analog A-234, developed under the FOLIANT program, "are as toxic as VX, as resistant to treatment as

soman Soman (or GD, EA 1210, Zoman, PFMP, A-255, systematic name: ''O''-pinacolyl methylphosphonofluoridate) is an extremely toxic chemical substance. It is a nerve agent, interfering with normal functioning of the mammalian nervous system by inhibiti ...

, and more difficult to detect and easier to manufacture than VX". Of the agent's

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that ta ...

versions, one is reportedly formed by

acetonitrile Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not clas ...

and an organic phosphate "that can be disguised as a pesticide precursor," while for another,

Bill Gertz William D. Gertz (born March 28, 1952) is an American editor, columnist and reporter for ''The Washington Times''. He is the author of eight books and writes a weekly column on the Pentagon and national security issues called "Inside the Ring". Du ...

wrote, "soldiers need only add alcohol". No certain data on toxicity exist but it is estimated that the median lethal concentration of A-234 is 7 mg/m³. This means that half of 70 kg men under slight physical activitybreathing 15 litres of air per minutewould die within two minutes of exposure. This equates to median lethal dose of 0.2 mg via respiration.

Regulated chemical under the Chemical Weapons Convention

A-234 has recently (entry into force 7 June 2020) been added to

Schedule 1 Schedule 1 may refer to: * Schedule I Controlled Substances within the US Controlled Substances Act * Schedule I Controlled Drugs and Substances within the Canadian Controlled Drugs and Substances Act * Schedule I Psychotropic Substances within t ...

of the Annex on Chemicals of the Chemical Weapons Convention and it has been explicitly named as an example compound for schedule 1.A.14. For chemicals listed in Schedule 1, the most stringent declaration and verification measures are in place combined with far-reaching limits and bans on production and use.

Alternative structure

An alternative structure for A-234 and the related Novichok agents had previously been proposed by Western chemical weapons experts such as Steven Hoenig and D. Hank Ellison. These structures were supported by Soviet literature of the time and were tested as

acetylcholinesterase inhibitor Acetylcholinesterase inhibitors (AChEIs) also often called cholinesterase inhibitors, inhibit the enzyme acetylcholinesterase from breaking down the neurotransmitter acetylcholine into choline and acetate, thereby increasing both the level and ...

s, however Mirzayanov explained that a number of weaker agents developed as part of the Foliant program were published in the open literature as organophosphate

pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...

s, in order to disguise the secret nerve agent program as legitimate pesticide research. However, the presence of a carbonimidic chloride fluoride group and a dimethylchloroethyl group suggest that this molecule is a member of the C-series of organophosphate agents (C01), with additional mustard and (chlorofluoro-)phosgene oxime radicals, added to produce skin and lung toxicity as well as

blistering A blister is a small pocket of fluid in the upper layer of the skin caused by heat, electricity, chemicals, light, radiation, or friction Blister(s) or Blistering may also refer to: * Anti-torpedo bulge, also known as an anti-torpedo blister * ...

effects.

References

{{Neurotoxins Acetylcholinesterase inhibitors Amidines Phosphorofluoridates Novichok agents

Regulated chemical under the Chemical Weapons Convention

Alternative structure

See also

References