Uses and Synthesis of Diphenylphosphine oxide

Diphenylphosphine oxide is an organophosphorus compound,it is an important intermediate in organic synthesis, widely used in the synthesis of various pesticides and chiral phosphine ligands.

Uses

Diphenylphosphine oxide is a commonly used chemical reagent in the laboratory. It is often used in the preparation of triphenylphosphine oxide, alkenyldiphenylphosphine oxide, addition to alkynes and Wittig-Horner reaction reagents.

Synthesis

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

(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 or diphenylphosphine.

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.

Thionyl chloride converts diphenylphosphine oxide to chlorodiphenylphosphine.

Organophosphinous acids are deoxygenated with DIBAH. The resulting secondary phosphines are precursors to phosphine ligands.

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