Methylphosphonic acid is an

organophosphorus compound Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective in ...

with the chemical formula CH₃P(O)(OH)₂. The phosphorus center is

tetrahedral In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ...

and is bonded to a methyl group, two OH groups and an oxygen. Methylphosphonic acid is a white, non-volatile solid that is poorly soluble in organic solvent but soluble in water and common alcohols.

Preparation

Methylphosphonic acid can be prepared from triethylphosphite by first using a Michaelis-Arbuzov reaction to generate the phosphorus(V) centre: :CH₃Cl + P(OC₂H₅)₃ → CH₃PO(OC₂H₅)₂ + C₂H₅Cl The resulting dialkylphosphonate is then treated with chlorotrimethylsilane before

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

of the siloxyphosphonate to generate the desired product. :CH₃PO(OC₂H₅)₂ + 2 Me₃SiCl → CH₃PO(OSiMe₃)₂ + 2 C₂H₅Cl
:CH₃PO(OSiMe₃)₂ + 2H₂O → CH₃PO(OH)₂ + 2 HOSiMe₃ The reaction pathway proceeds via the siloxyphosphonate intermediate due to the difficulty in directly hydrolysing dialkylphosphonates. Katritzky and co-workers published a one-pot synthesis of methylphosphonic acid in 1989.

References

{{Organophosphorus Phosphonic acids Organic compounds with 1 carbon atom