Diphenylphosphine oxide

Diphenylphosphine oxide is an organophosphorus compound with the formula (C₆H₅)₂P(O)H. It is a white solid that soluble in polar organic solvents. The compound is used in Buchwald-Hartwig coupling reactions to introduce a diphenylphosphino substituent. Analogous to the behavior of phosphorous acid, diphenylphosphine oxide exists in equilibrium with a minor tautomer hydroxydiphenylphosphine (CAS#24630-80-6) (C₆H₅)₂POH.