Trimethyl phosphate

Trimethyl phosphate
Other names phosphoric acid trimethyl ester TMP methyl phosphate, trimethoxyphosphine oxide trimethyl orthophosphate
Identifiers
CAS number	512-56-1 Y
PubChem	10541
ChemSpider	10101 Y
ChEBI	CHEBI:46324 Y
Jmol-3D images	Image 1
SMILES O=P(OC)(OC)OC
InChI InChI=1S/C3H9O4P/c1-5-8(4,6-2)7-3/h1-3H3 Y Key: WVLBCYQITXONBZ-UHFFFAOYSA-N Y InChI=1/C3H9O4P/c1-5-8(4,6-2)7-3/h1-3H3 Key: WVLBCYQITXONBZ-UHFFFAOYAV
Properties
Molecular formula	(CH3)3PO4
Molar mass	140.08
Appearance	Colorless liquid
Melting point	-46 °C
Boiling point	197 °C
Hazards
EU classification	Harmful substances or preparations (Xn)
R-phrases	R22,R36/37/38
S-phrases	S36/37,S45
NFPA 704	1 2 0
Y phosphate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Trimethyl phosphate is the trimethyl ester of phosphoric acid. It is a colourless, nonvolatile liquid. It has some specialized uses in the production of other compounds.^[1]

Production

Trimethyl phosphate is prepared by treating phosphorus oxychloride with methanol in the presence of an amine base:

POCl₃ + 3 CH₃OH + 3 R₃N → PO(OCH₃)₃ + 3 R₃NH⁺Cl^-

It is a tetrahedral molecule that is a weakly polar solvent.

Applications

Trimethyl phosphate is a mild methylating agent, useful for preparing dimethylation of anilines and related heterocyclic compounds.^[2] 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.

Other applications

It is used as a color inhibitor for fibers (e.g. polyester) and other polymers.

Safety considerations

With an LD50 of 2g/kg for rats, trimethylphosphate is expected to have low acute toxicity.^[3]

References

1. ^ D. E. C. Corbridge "Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology" 5th Edition Elsevier: Amsterdam 1995. ISBN 0-444-89307-5.
2. ^ William A. Sheppard (1973), "m-Trifluoromethyl-N,N-dimethylaniline", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV5P1085 ; Coll. Vol. 5: 1085 
3. ^ J. Svara, N. Weferling, T. Hofmann "Phosphorus Compounds, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2006. doi:10.1002/14356007.a19_545.pub2

External links

• WebBook page for C3H9PO4