Triethyl phosphite
Names
Preferred IUPAC name
Triethyl phosphite
Other names
Triethoxyphosphine
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.139
UNII
  • InChI=1S/C6H15O3P/c1-4-7-10(8-5-2)9-6-3/h4-6H2,1-3H3 checkY
    Key: BDZBKCUKTQZUTL-UHFFFAOYSA-N checkY
  • InChI=1/C6H15O3P/c1-4-7-10(8-5-2)9-6-3/h4-6H2,1-3H3
    Key: BDZBKCUKTQZUTL-UHFFFAOYAP
  • O(P(OCC)OCC)CC
Properties
C6H15O3P
Molar mass 166.157 g·mol−1
Appearance colorless liquid
Density 0.969 g/mL
Melting point −70 °C (−94 °F; 203 K)
Boiling point 156 °C (313 °F; 429 K) (57 to 58 °C at 16 mm)
Solubility soluble in most organic solvents
-104.8·10−6 cm3/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 toxic
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

Triethyl phosphite is an organophosphorus compound, specifically a phosphite ester, with the formula P(OCH2CH3)3, often abbreviated P(OEt)3. It is a colorless, malodorous liquid. It is used as a ligand in organometallic chemistry and as a reagent in organic synthesis.

The molecule features a pyramidal phosphorus(III) center bound to three ethoxide groups. Its 31P NMR spectrum features a signal at around +139 ppm vs phosphoric acid standard.

Triethylphosphite is prepared by treating phosphorus trichloride with ethanol in the presence of a base, typically a tertiary amine:[1]

PCl3 + 3 EtOH + 3 R3N → P(OEt)3 + 3 R3NH + 3 Cl−

In the absence of the base, the reaction of ethanol and phosphorus trichloride affords diethylphosphite ((EtO)2P(O)H). Of the many related compounds can be prepared similarly, triisopropyl phosphite is an example (b.p. 43.5 °C/1.0 mm; CAS# 116-17-6).

Reactions

Triethyl phosphite can react with electrophiles in a Michaelis–Arbuzov reaction to produce organophosphonates. For example, the reaction between triethyl phosphite and ethyl bromoacetate produces a phosphonate suitable for use in the Horner–Wadsworth–Emmons reaction.[2]

Michaelis–Arbuzov reaction between ethyl bromoacetate and triethyl phosphite resulting in an organophosphonate.
Michaelis–Arbuzov reaction between ethyl bromoacetate and triethyl phosphite resulting in an organophosphonate.

Reduction/deoxygenation of hydroperoxides to the alcohols can also be effected using triethyl phosphite.[2] This approach can be utilized for carbonyl α-hydroxylation by reacting the enolate with oxygen, producing an α-hydroperoxide which can be reduced by triethyl phosphite to the alcohol.[3] A proposed mechanism is shown below.[4]

Reaction scheme and proposed mechanism for carbonyl α-hydroxylation using oxygen and triethyl phosphite.
Reaction scheme and proposed mechanism for carbonyl α-hydroxylation using oxygen and triethyl phosphite.

Triethyl phosphite can also be used in the Corey–Winter olefin synthesis.[2]

As a ligand

In coordination chemistry and homogeneous catalysis, triethylphosphite finds use as a soft ligand. Its complexes are generally lipophilic and feature metals in low oxidation states. Examples include the colorless complexes FeH2(P(OEt)3)4 and Ni(P(OEt)3)4 (m.p. 108 °C).[5] It also forms a stable complex with copper(I) iodide.[2]

References

  1. ↑ Ford-Moore, A. H.; Perry, B. J. (1951). "Triethyl Phosphite". Org. Synth. 31: 111. doi:10.15227/orgsyn.031.0111.
  2. 1 2 3 4 Piscopio, Anthony D.; Shakya, Sagar (2005). "Triethyl Phosphite". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt224.pub2.
  3. ↑ Gardner, J. N.; Carlon, F. E.; Gnoj, O. (1968). "One-step procedure for the preparation of tertiary α-ketols from the corresponding ketones". The Journal of Organic Chemistry. 33 (8): 3294–3297. doi:10.1021/jo01272a055.
  4. ↑ Liang, Yu-Feng; Jiao, Ning (2014). "Highly Efficient C–H Hydroxylation of Carbonyl Compounds with Oxygen under Mild Conditions". Angewandte Chemie International Edition. 53 (2): 548–552. doi:10.1002/anie.201308698.
  5. ↑ Ittel, Steven D. (1990). "Complexes of Nickel(0)". Inorganic Syntheses. 28: 98–104. doi:10.1002/9780470132593.ch26. ISBN 978-0-470-13259-3.
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