PALLADIUM-CATALYZED OXIDATION OF TRIPHENYLPHOSPHINE

Abstract

In the presence of Pd(II) catalyst, triphenylphosphine can be oxidized with molecular oxygen at room temperature under atmospheric pressure to form triphenylphosphine oxide. The rate of oxidation depended on the type of anionic ligand of palladium salt. The oxidation was inhibited by protic solvents and coordinating solvents such as amine. For palladium acetate as a catalyst, the square planar structure of Pd(OAc)2(PPh3)]2 was converted into the dimeric structure, [Pd(OAc)2(PPh3)2, as triphenylphosphine was consumed. Finally palladium metal precipitated when triphenylphosphine was oxidized completely. A possible reaction scheme of the Pd(II)-catalyzed oxidation of triphenylphosphine is proposed