Phosphonic esters are prepared using the Michaelis–Arbuzov reaction. For example, methyl iodide catalyses the conversion of trimethylphosphite to the phosphonate ester dimethyl methylphosphonate:
:P(OMe) → MePO(OMe)
These esters can be hydrolysed to the acid (Me = methyl):
:MePO(OMe) + HO → MePO(OH) + 2 MeOH
In the Michaelis–Becker reaction, a hydrogen phosphonate diester is first deprotonated and the resulting anion is alkylated.