Methyldichlorophosphine
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| ImageFile = Methyldichlorophosphine.svg
| ImageSize = 120px
| PIN = Methylphosphonous dichloride
| OtherNames = Methyl phosphonous dichloride, Dichloromethylphosphine, SW{{cite web|url=https://apps.dtic.mil/sti/tr/pdf/ADA422058.pdf|title=Infrared Spectroscopic Observations on the Fate of Organophosphorus Compounds Exposed to Atmospheric Moisture. Part I. G-Agents and Related Compounds}}
| Section1 = {{Chembox Identifiers
| CASNo = 676-83-5
| PubChem = 61194
| ChemSpiderID = 55138
| EC_number = 211-631-8
| UNNumber = 2845
| SMILES = CP(Cl)Cl
| InChI=1S/CH3Cl2P/c1-4(2)3/h1H3
| InChIKey=CDPKWOKGVUHZFR-UHFFFAOYSA-N
}}
| Section2 = {{Chembox Properties
| C=1|H=3|Cl=2|P=1
| Appearance = Colorless liquid
| Density =
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| Section3 = {{Chembox Hazards
| MainHazards =
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Methyldichlorophosphine (alternatively known as dichloro(methyl)phosphane, SW and methylphosphonous dichloride) is an organophosphorus compound with the chemical formula CH3PCl2. It is a colorless, corrosive, flammable, and highly reactive liquid with a pungent odor.
Preparation
Methyldichlorophosphine is produced by alkylation of phosphorus trichloride with methyl iodide followed by reduction of the resulting phosphonium salt with iron powder:{{cite book|title=Synthesis of Carbon–Phosphorus Bonds|year=2004|author=Robert Engel |author2=JaimeLee Iolani Cohen |publisher= CRC|isbn=0-8493-1617-0}}{{citation | vauthors = Mirosław S | title = A Simple Preparation of Methylphosphonous Dichloride | journal = Synthesis | issue = 7 | pages = 450 | date = 1977 | volume = 1977 | doi = 10.1055/s-1977-24435 }}
:CH3I + PCl3 + AlCl3 → [CH3PCl3]+AlCl3I−
:[CH3PCl3]+AlCl3I− + Fe → CH3PCl2 + FeICl + AlCl3
The compound is an intermediate for the synthesis of other chemicals for instance dimethylphenylphosphine.
Uses
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.{{citation | contribution=Phosphorus Compounds, Organic | title=Ullmann's Encyclopedia of Industrial Chemistry | edition=7th | year=2007 | doi=10.1002/14356007.a19_545.pub2 | last1=Svara | first1=Jürgen | last2=Weferling | first2=Norbert | last3=Hofmann | first3=Thomas | isbn=978-3-527-30385-4 }}
Due to the recycling problem of phosphoryl chloride, SW was adopted in step three of the DMHP process in the preparation of Sarin.Sass, S; Morgan, C. U. Chlorination End-Point Indication by Conductivity and Color Change (Step III, DMHP Process). Formal rept. 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.cit-OPDC. The preparatory manual to chemical warfare. Vol 1: V agents: X
Safety
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.{{cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/Methyldichlorophosphine#section=Stability-and-Reactivity|title=Dichloro(methyl)phosphane|last=Pubchem|website=pubchem.ncbi.nlm.nih.gov|access-date=19 April 2018}}