Trimethyl phosphate is the trimethyl ester of phosphoric acid. It is a colourless, nonvolatile liquid. It has the chemical formula or . It has some specialized uses in the production of other compounds.
Trimethyl phosphate is prepared by treating phosphorus oxychloride with methanol in the presence of an amine base:
It is a tetrahedral molecule that is a weakly polar solvent.
Trimethyl phosphate is a mild methylating agent, useful for dimethylation of anilines and related heterocyclic compounds. The method is complementary to the traditional Eschweiler-Clarke reaction in cases where formaldehyde engages in side reactions.
Trimethyl phosphate is used as a solvent for aromatic halogenations and nitrations as required for the preparation of pesticides and pharmaceuticals.
It is used as a color inhibitor for fibers (e.g. polyester) and other polymers. Trimethyl phosphate is used as a simulant for chemical weapon nerve agents.
With an LD50 of 2g/kg for rats, trimethylphosphate is expected to have low acute toxicity.