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 with a pungent odor.

Preferred IUPAC name
Methylphosphonous dichloride
Other names
Methyl phosphonous dichloride, Dichloromethylphosphine
  • 676-83-5
3D model (JSmol)
  • Interactive image
  • 55138
ECHA InfoCard 100.010.575 Edit this at Wikidata
EC Number
  • 211-631-8
  • 61194
UN number 2845
  • DTXSID1060978 Edit this at Wikidata
  • InChI=1S/CH3Cl2P/c1-4(2)3/h1H3
  • CP(Cl)Cl
Molar mass 116.91 g·mol−1
Appearance Colorless liquid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references


Methyldichlorophosphine is produced by alkylation of phosphorus trichloride with methyl iodide followed by reduction of the resulting phosphonium salt with iron powder:[1] The compound is an intermediate for the synthesis of other chemicals for instance dimethylphenylphosphine:

CH3I + PCl3 + AlCl3 → [CH3PCl3]+AlCl3I
[CH3PCl3]+AlCl3I + Fe → CH3PCl2 + FeClI + AlCl3

SW used for chemical warfare purposes was prepared by this process.[2] For this, the process adopted was the Clayton-Jensen reaction to prepare the SW.[3]


Methyldichlorophosphine belongs to the group of halophosphines, some of which are used as intermediates in the production of plant protection agents, stabilizers for plastics, and catalysts. It is a precursor of the herbicide Glufosinate. It is also used in the production of flameproofing compounds.[4]

Due to the recycling problem of phosphoryl chloride, SW was adopted in step three of the DMHP process in the preparation of GB.[5] SW was also adopted as a standard precursor to V agents, having been used to prepare QL for unitary and binary VX. SW was the first agent adopted to prepare VX in one pot reaction by aqueous medium.[6]


It is also toxic if inhaled, can cause burns upon contact with the skin and eyes, and releases fumes of hydrochloric acid in moist environments.[7]


  1. ^ Robert Engel, JaimeLee Iolani Cohen (2004). Synthesis of Carbon–Phosphorus Bonds. CRC. ISBN 0-8493-1617-0.{{cite book}}: CS1 maint: uses authors parameter (link)
  2. ^ Installation Assessment of Phosphate Development Works (PDW), AL. Report No. 177. p-4
  3. ^ Wang, Zerong (2010-09-15). Comprehensive Organic Name Reactions and Reagents. Hoboken, NJ, USA: John Wiley & Sons, Inc. doi:10.1002/9780470638859. ISBN 978-0-470-63885-9.
  4. ^ "Phosphorus Compounds, Organic", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), 2007, doi:10.1002/14356007.a19_545.pub2
  5. ^ Sass, S; Morgan, C. U. Chlorination End-Point Indication by Conductivity and Color Change (Step III, DMHP Process). Formal rept.
  6. ^ cit-OPDC. The preparatory manual to chemical warfare. Vol 1: V agents: X
  7. ^ Pubchem. "Dichloro(methyl)phosphane". Retrieved 19 April 2018.