POCl3; PCl5 Triphenylphosphine oxide (often abbreviated TPPO) is the organophosphorus compound with the formula OP(C6H5)3, also written as Ph3PO or PPh3O (Ph = C6H5).

This colourless crystalline compound is a common but potentially useful waste product in reactions involving triphenylphosphine.

Trituration or chromatography of crude products with these solvents often leads to a good separation of triphenylphosphine oxide.

Its removal is facilitated by conversion to its Mg(II) complex, which is poorly soluble in toluene or dichloromethane and can be filtered off.

[7] An alternative filtration method where ZnCl2(TPPO)2 is formed upon addition of ZnCl2 may be used with more polar solvents such as ethanol, ethyl acetate and tetrahydrofuran.