Trimethyl phosphite
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Names | |||
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Preferred IUPAC name
Trimethyl phosphite[1] | |||
Other names
Trimethoxyphosphine
Trimethoxyphosphane | |||
Identifiers | |||
3D model (
JSmol ) |
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ChEBI | |||
ChemSpider | |||
ECHA InfoCard
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100.004.065 | ||
PubChem CID
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UNII | |||
CompTox Dashboard (EPA)
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Properties | |||
C3H9O3P | |||
Molar mass | 124.08 | ||
Appearance | colorless liquid | ||
Odor | distinctive, pungent[2] | ||
Density | 1.052 | ||
Melting point | −78 °C (−108 °F; 195 K) | ||
Boiling point | 111 °C (232 °F; 384 K) | ||
reacts[2] | |||
Vapor pressure | 24 mmHg (25°C)[2] | ||
Hazards | |||
Flash point | 28 °C; 82 °F; 301 K[2] | ||
NIOSH (US health exposure limits): | |||
PEL (Permissible)
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none[2] | ||
REL (Recommended)
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TWA 2 ppm (10 mg/m3)[2] | ||
IDLH (Immediate danger) |
N.D.[2] | ||
Related compounds | |||
Related compounds
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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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Trimethyl phosphite is an
methoxy
groups.
Synthesis
Trimethyl phosphite is in principle obtainable by methanolysis of phosphorus trichloride, say in the presence of a proton accepting base. This method suffers from numerous side reactions however. The use of sodium methoxide is superior:[3]
- PCl3 + 3 NaOCH3 → P(OCH3)3 + 3 NaCl
Reactions
Trimethyl phosphite is susceptible to oxidation to trimethyl phosphate:
- P(OCH3)3 + 0.5 O2 → OP(OCH3)3
It reacts with a catalytic amount of methyl iodide in the
Arbuzov reaction to give dimethyl methylphosphonate
:
- P(OCH3)3 → CH3P(O)(OCH3)2
As a ligand, trimethyl phosphite 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).[4] The tridentate ligand called the Kläui ligand
is derived from trimethyl phosphite. The formation of this ligand illustrates the susceptibility of trimethyl phosphite (and metal complexes thereof) to the Arbuzov reaction.
Trimethyl phosphite is also used as a mild desulfurization reagent in organic synthesis, for example in the preparation of derivatives of tetrathiafulvalene.[5]
Toxicity
The
LD50 is 1600–2890 mg/kg (oral, rat).[6]
References
- ISBN 978-0-85404-182-4.
- ^ a b c d e f g NIOSH Pocket Guide to Chemical Hazards. "#0640". National Institute for Occupational Safety and Health (NIOSH).
- .
- ISBN 978-0-471-52619-3.
- .
- ISBN 978-3527306732.