Methylphosphonic acid dichloride

Methylphosphonic acid dichloride
Names
	Preferred IUPAC name Methylphosphonic dichloride
	Other names Methanephosphonic dichloride; Methanephosphonic acid dichloride; Methylphosphonyl dichloride
Identifiers
CAS Number	676-97-1;
3D model (JSmol)	Interactive image;
ChemSpider	12150;
ECHA InfoCard	100.010.578
EC Number	211-634-4;
PubChem CID	12671;
CompTox Dashboard (EPA)	DTXSID6060979 ;
	InChI InChI=1S/CH3Cl2OP/c1-5(2,3)4/h1H3 Key: SCLFRABIDYGTAZ-UHFFFAOYSA-N; InChI=1/CH3Cl2OP/c1-5(2,3)4/h1H3 Key: SCLFRABIDYGTAZ-UHFFFAOYAS;
	SMILES CP(=O)(Cl)Cl;
Properties
Chemical formula	CH3Cl2OP
Molar mass	132.91 g·mol−1
Appearance	White crystalline solid
Density	1.468 g/mL at 20 °C
Melting point	28 to 34 °C (82 to 93 °F; 301 to 307 K)
Boiling point	163 °C (325 °F; 436 K)
Hazards
Main hazards	Very Toxic
R-phrases (outdated)	R14, R23/24/25, R26, R34
Flash point	>110 °C
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	26 ppm/4h by inhalation (rat)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	Infobox references

Methyl phosphonic dichloride is an organophosphorus compound. It has a number of potential uses but is most notable as being a precursor to several chemical weapons agents. It is a white crystalline solid, with a low melting point. It hydrolyzes readily and must be handled with care as it is exceedingly toxic.

Synthesis and reactions

Methyl phosphonic dichloride is produced by oxidation of methyldichlorophosphine, e.g. with sulfuryl chloride:[1]

MePCl₂ + SO₂Cl₂ → MeP(O)Cl₂ + SOCl₂

It can also be produced from a range of methyl-phosphonates (e.g. dimethyl methylphosphonate) via chlorination with thionyl chloride. Various amines can be used to catalyse this process.[2] It reacts with hydrogen fluoride or sodium fluoride to produce methylphosphonyl difluoride, which is used in the production of sarin and soman nerve agents.

References

Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," In 'Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2008. doi:10.1002/14356007.a19_545.pub2.
Maier, Ludwig (1990). "ORGANIC PHOSPHORUS COMPOUNDS 90.l A CONVENIENT, ONE-STEP SYNTHESIS OF ALKYL- AND ARYLPHOSPHONYL DICHLORIDES". Phosphorus, Sulfur, and Silicon and the Related Elements. 47 (3–4): 465–470. doi:10.1080/10426509008038002.

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[Svara-1] Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," In 'Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2008. doi:10.1002/14356007.a19_545.pub2.

[2] Maier, Ludwig (1990). "ORGANIC PHOSPHORUS COMPOUNDS 90.l A CONVENIENT, ONE-STEP SYNTHESIS OF ALKYL- AND ARYLPHOSPHONYL DICHLORIDES". Phosphorus, Sulfur, and Silicon and the Related Elements. 47 (3–4): 465–470. doi:10.1080/10426509008038002.