Methylphosphonyl dichloride (DC) or dichloro is an

organophosphorus compound Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective in ...

. It has a number of commercial uses but is most notable as being a precursor to several

chemical weapon A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as ...

s agents. It is a white crystalline solid that melts slightly above room temperature.

Synthesis and reactions

Methylphosphonyl dichloride is produced by oxidation of

methyldichlorophosphine Methyldichlorophosphine (alternatively known as dichloro(methyl)phosphane and methyl phosphonous dichloride) is an organophosphorus compound with the chemical formula CH3PCl2. It is a colorless, corrosive, flammable, and highly reactive liquid wit ...

, with

sulfuryl chloride Sulfuryl chloride is an inorganic compound with the formula SO2Cl2. At room temperature, it is a colorless liquid with a pungent odor. Sulfuryl chloride is not found in nature, as can be inferred from its rapid hydrolysis. Sulfuryl chloride is ...

:Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," In 'Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2008. . :CH₃PCl₂ + SO₂Cl₂ → CH₃P(O)Cl₂ + SOCl₂ It can also be produced from a range of methylphosphonates (e.g.

dimethyl methylphosphonate Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petr ...

) via chlorination with

thionyl chloride Thionyl chloride is an inorganic compound with the chemical formula . It is a moderately volatile, colourless liquid with an unpleasant acrid odour. Thionyl chloride is primarily used as a chlorinating reagent, with approximately per year bein ...

. Various

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent su ...

s catalyse this process. With hydrogen fluoride or

sodium fluoride Sodium fluoride (NaF) is an inorganic compound with the formula . It is used in trace amounts in the fluoridation of drinking water, in toothpaste, in metallurgy, and as a flux. It is a colorless or white solid that is readily soluble in water. ...

, it can be used to produce

methylphosphonyl difluoride Methylphosphonyl difluoride (DF), also known as EA-1251 or difluoro, is a chemical weapon precursor. Its chemical formula is CH3POF2. It is a Schedule 1 substance under the Chemical Weapons Convention. It is used for production of sarin and som ...

. With alcohols, it converts to the dialkoxide: :CH₃P(O)Cl₂ + 2HOR → CH₃P(O)(OR)₂ + HCl

Safety

Methylphosphonyl dichloride is very toxic and reacts vigorously with water to release

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dig ...

. It is also listed under Schedule 2 of the

Chemical Weapons Convention The Chemical Weapons Convention (CWC), officially the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction, is an arms control treaty administered by the Organisation for ...

as it is used in the production of organophosphorus

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 ...

s such as

sarin Sarin (NATO designation GB G-series, "B"">Nerve_agent#G-series.html" ;"title="hort for Nerve agent#G-series">G-series, "B" is an extremely toxic synthetic organophosphorus compound.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 ...

References

{{Chemical agents Nerve agent precursors Organophosphorus compounds Organic compounds with 1 carbon atom