|Preferred IUPAC name
dimethylphosphinous acid tautomer
3D model (JSmol)
|Molar mass||78.051 g·mol−1|
|Boiling point||65–67 ºC|
|H302, H315, H319, H335|
|P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Dimethylphosphine oxide is an organophosphorus compound with the formula (CH3)2P(O)H. It is a colorless liquid that soluble in polar organic solvents. It exists as the phosphine oxide, not the hydroxy tautomer. A related compound is diphenylphosphine oxide. Both are sometimes called secondary phosphine oxides.
The compound arises by the hydrolysis of chlorodimethylphosphine:
- Me2PCl + H2O → Me2P(O)H + HCl
Methanol, but not ethanol, can also be used in place of water, the co-product being methyl chloride.
Since chlorodimethylphosphine is dangerous to handle, alternative routes to dimethylphosphine oxide have been developed. A popular method starts with diethylphosphite, according to the following idealized equations:
- (C2H5O)2P(O)H + 3 CH3MgBr → (CH3)2P(O)MgBr + 2 MgBr(OC2H5) + CH4
- (CH3)2P(O)MgBr + H2O → (CH3)2P(O)H + 2 MgBr(OH)
Chlorination gives dimethylphosphoryl chloride. It undergoes hydroxymethylation with formaldehyde.
- Me2P(O)H + CH2O → Me2P(O)CH2OH
Many aldehydes effect a similar reaction.
- Kleiner, H. J. (1974). "Herstellung und Umsetzungen von Dimethylphosphinoxid (Preparation and Reactions of Dimethylphosphine Oxide)". Justus Liebigs Ann. Chem.: 751–764. doi:10.1002/jlac.197419740507.
- Hays, H. R. (1968). "Reaction of diethyl phosphonate with methyl and ethyl Grignard reagents". J. Org. Chem. 33: 3690–3694. doi:10.1021/jo01274a003.