Methylphosphonyl dichloride

Methylphosphonyl dichloride
Names
	Preferred IUPAC name Methylphosphonic dichloride
	Other names Methanephosphonic dichloride; Methanephosphonic acid dichloride; Methylphosphonyl dichloride; Dichloro
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;
UN number	9206
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)
Solubility in water	Reacts with water
Solubility	Ether, THF
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Very toxic, reacts with water
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314, H330
Precautionary statements	P260, P264, P271, P280, P284, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P320, P321, P363, P403+P233, P405, P501
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

Methylphosphonyl dichloride (DC) or dichloro is an organophosphorus compound. It has a number of commercial uses^[vague] but is most notable as being a precursor to several chemical weapons agents. It is a white crystalline solid that melts slightly above room temperature.^[1]

Synthesis and reactions

Methylphosphonyl dichloride is produced by oxidation of methyldichlorophosphine, with sulfuryl chloride:^[2]

CH₃PCl₂ + SO₂Cl₂ → CH₃P(O)Cl₂ + SOCl₂

It can also be produced from a range of methylphosphonates (e.g. dimethyl methylphosphonate) via chlorination with thionyl chloride. Various amines catalyse this process.^[3] With hydrogen fluoride or sodium fluoride, it can be used to produce methylphosphonyl difluoride. With alcohols, it converts to the dialkoxide:^[4]

CH₃P(O)Cl₂ + 2 HOR → CH₃P(O)(OR)₂ + HCl

Safety

Methylphosphonyl dichloride is very toxic and reacts vigorously with water to release hydrochloric acid. It is also listed under Schedule 2 of the Chemical Weapons Convention as it is used in the production of organophosphorus nerve agents such as sarin and soman.

References

^ "SAFETY DATA SHEET Methylphosphonic dichloride". SAFETY DATA SHEET Methylphosphonic dichloride. MilliporeSigma. June 26, 2020. Retrieved April 27, 2022.
^ 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.
^ Carl Patois, Philippe Savignac, Elie About-Jaudet, Noël Collignon (1996). "Bis(Trifluoroethyl) (carboethoxymethyl)phosphonate". Organic Syntheses. 73: 152. doi:10.15227/orgsyn.073.0152.{{cite journal}}: CS1 maint: multiple names: authors list (link)

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[1] "SAFETY DATA SHEET Methylphosphonic dichloride". SAFETY DATA SHEET Methylphosphonic dichloride. MilliporeSigma. June 26, 2020. Retrieved April 27, 2022.

[Svara-2] 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.

[3] 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.

[4] Carl Patois, Philippe Savignac, Elie About-Jaudet, Noël Collignon (1996). "Bis(Trifluoroethyl) (carboethoxymethyl)phosphonate". Organic Syntheses. 73: 152. doi:10.15227/orgsyn.073.0152.{{cite journal}}: CS1 maint: multiple names: authors list (link)