Methylphosphonic acid dichloride


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.

Synthesis and reactions

Methyl phosphonic dichloride is produced by oxidation of methyldichlorophosphine, e.g. with sulfuryl chloride:
It can also be produced from a range of methyl-phosphonates via chlorination with thionyl chloride. Various amines can be used to catalyse this process.
It reacts with hydrogen fluoride or sodium fluoride to produce methylphosphonyl difluoride, which is used in the production of sarin and soman nerve agents.