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.

Preparation

Methyldichlorophosphine is produced by alkylation of

phosphorus trichloride Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic a ...

with

methyl iodide Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one h ...

followed by reduction of the resulting phosphonium salt with iron powder: The compound is an intermediate for the synthesis of other chemicals for instance dimethylphenylphosphine: :CH₃I + PCl₃ + AlCl₃ → H₃PCl₃sup>+AlCl₃I⁻ : H₃PCl₃sup>+AlCl₃I⁻ + Fe → CH₃PCl₂ + FeClI + AlCl₃

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 Glufosinate (also known as phosphinothricin and often sold as an ammonium salt) is a naturally occurring broad-spectrum herbicide produced by several species of ''Streptomyces'' soil bacteria. Glufosinate is a non-selective, contact herbicide, w ...

. It is also used in the production of flameproofing compounds. Due to the recycling problem of

phosphoryl chloride Phosphoryl chloride (commonly called phosphorus oxychloride) is a colourless liquid with the formula . It hydrolyses in moist air releasing phosphoric acid and fumes of hydrogen chloride. It is manufactured industrially on a large scale from phosp ...

, SW was adopted in step three of the DMHP process in the preparation of GB. 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.

Safety

It is also toxic if inhaled, can cause burns upon contact with the skin and eyes, and releases fumes of

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

in moist environments.

References

{{Chemical agents Herbicides Nerve agent precursors Phosphines