Trimethyl phosphate

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]

Trimethyl phosphate
Names
Preferred IUPAC name
Trimethyl phosphate
Other names
Phosphoric acid trimethyl ester
Methyl phosphate,
Trimethoxyphosphine oxide
Trimethyl orthophosphate
Identifiers
3D model (JSmol)
Abbreviations TMP
ChEBI
ChemSpider
ECHA InfoCard 100.007.405
UNII
Properties
(CH3O)3PO
Molar mass 140.08
Appearance Colorless liquid
Melting point −46 °C (−51 °F; 227 K)
Boiling point 197 °C (387 °F; 470 K)
good
Hazards
Harmful substances or preparations (Xn)
R-phrases (outdated) R22,R36/37/38
S-phrases (outdated) S36/37,S45
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
2
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

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 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". Organic Syntheses.; Collective Volume, 5, p. 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
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