Trimethyl phosphite

Trimethyl phosphite
Names
IUPAC name
Trimethyl phosphite
Other names
Trimethoxyphosphine
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.065
Properties
C3H9O3P
Molar mass 124.08
Appearance colorless liquid
Odor distinctive, pungent[1]
Density 1.052
Melting point −78 °C (−108 °F; 195 K)
Boiling point 111 °C (232 °F; 384 K)
reacts[1]
Vapor pressure 24 mmHg (25°C)[1]
Hazards
Flash point 28 °C; 82 °F; 301 K [1]
US health exposure limits (NIOSH):
PEL (Permissible)
 none[1]
REL (Recommended)
 TWA 2 ppm (10 mg/m3)[1]
IDLH (Immediate danger)
 N.D.[1]
Related compounds
Related compounds
 Dimethyl methylphosphonate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Trimethylphosphite is an organophosphorus compound with the formula P(OCH3)3, often abbreviated P(OMe)3. This colorless liquid is used as a ligand in organometallic chemistry and as a reagent in organic synthesis. The material also has a highly pungent smell. The molecule features a pyramidal phosphorus(III) center bound to three methoxy groups.

Synthesis and reactions

Trimethylphosphite is prepared from phosphorus trichloride:

It is susceptible to oxidation to trimethyl phosphate.

It reacts with a catalytic amount of methyl iodide in the Arbuzov reaction to give dimethyl methylphosphonate:

P(OCH3) → CH3)P(O)(OCH2)

As a ligand, trimethylphosphite has a smaller cone angle and better acceptor properties relative to trimethylphosphine. A representative derivative is the colorless, tetrahedral complex Ni(P(OMe)3)4 (m.p. 108 °C).[2] The tridentate ligand called the Klaui ligand is derived from trimethylphosphite. The formation of this ligand illustrates the susceptibility of trimethylphosphite (and metal complexes thereof) to the Arbuzov reaction.

Trimethylphosphite is also used as a mild desulfurization reagent in organic synthesis, for example in the preparation of derivatives of tetrathiafulvalene.[3]

Toxicity

The LD50 is 1600–2890 mg/kg (oral, rat).[4]

References

  1. 1 2 3 4 5 6 7 "NIOSH Pocket Guide to Chemical Hazards #0640". National Institute for Occupational Safety and Health (NIOSH).
  2. ↑ Ittel, Steven D.; Ittel, S. D.; Cushing, M. A. (1990). "Complexes of Nickel(0)". Inorganic Syntheses. Inorganic Syntheses. 28: 98–104. doi:10.1002/9780470132593.ch25. ISBN 978-0-471-52619-3.
  3. ↑ Jan Larsen and Christine Lenoir (1998). "2,2'-Bi-5,6-Dihydro-1,3-Dithiolo[4,5-b][1,4]dithiinylidene (BEDT-TTF)". Organic Syntheses. ; Collective Volume, 9, p. 72 .
  4. ↑ Svara, J.; Weferling, N.; Hofmann, T., "Phosphorus Compounds, Organic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a19_545.pub2
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