Diphenylphosphine oxide

Diphenylphosphine oxide is an organophosphorus compound with the formula (C₆H₅)₂P(O)H. It is a white solid that is soluble in polar organic solvents.^[1]

Diphenylphosphine oxide

Ball-and-stick model of the diphenylphosphine oxide molecule
Names
Preferred IUPAC name Diphenyl-λ5-phosphanone
Identifiers
CAS Number	4559-70-0 Y
3D model (JSmol)	Interactive image
ChemSpider	222625
PubChem CID	254003
UNII	XXW49HG6X3 Y
InChI InChI=1S/C12H11OP/c13-14(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10,14H Key: ASUOLLHGALPRFK-UHFFFAOYSA-N
SMILES c1ccc(cc1)P(=O)c2ccccc2
Properties
Chemical formula	C12H11OP
Molar mass	202.19
Appearance	white solid
Melting point	56-57 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis

Diphenylphosphine oxide can be prepared by the reaction of phosphonic esters, such as diethylphosphite, with Grignard reagents followed by acid workup:^[2]

(C₂H₅O)₂P(O)H + 3 C₆H₅MgBr → (C₆H₅)₂P(O)MgBr + C₂H₅OMgBr

(C₆H₅)₂P(O)MgBr + HCl → (C₆H₅)₂P(O)H + MgBrCl

Alternatively, it may be prepared by the partial hydrolysis of chlorodiphenylphosphine^[1] or diphenylphosphine.^[3]

Reactions

Diphenylphosphine oxide exists in equilibrium with its minor tautomer diphenylphosphinous acid, ((C₆H₅)₂POH:

(C₆H₅)₂P(O)H ⇌ (C₆H₅)₂POH

Diphenylphosphine oxide is used in Buchwald-Hartwig coupling reactions to introduce diphenylphosphino substituents.^[1]

Thionyl chloride converts diphenylphosphine oxide to chlorodiphenylphosphine.

Organophosphinous acids are deoxygenated with DIBAH. The resulting secondary phosphines are precursors to phosphine ligands.^[4]