Methylphosphonic acid dichloride

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Methylphosphonic acid dichloride
Methylphosphonic dichloride-2D-by-AHRLS-2012.png
Preferred IUPAC name
Methylphosphonic dichloride
Other names
Methanephosphonic dichloride
Methanephosphonic acid dichloride
Methylphosphonyl dichloride
3D model (JSmol)
ECHA InfoCard 100.010.578 Edit this at Wikidata
EC Number
  • 211-634-4
  • InChI=1S/CH3Cl2OP/c1-5(2,3)4/h1H3
  • InChI=1/CH3Cl2OP/c1-5(2,3)4/h1H3
  • CP(=O)(Cl)Cl
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)
Main hazards Very Toxic
R-phrases (outdated) R14, R23/24/25, R26, R34
Flash point >110 °C
Lethal dose or concentration (LD, LC):
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.[citation needed]

Synthesis and reactions[edit]

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.


  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.