Electrochemical generation of phosphine oxide

The electrochemical generation of H3PO was performed in a single electrochemical cell with a lead cathode and a sacrificial zinc anode using P4 melted in a slightly acidic water/ethanol solution (2:1 volume ratio, water acidified with HCl, 2m) at 60 C. The overall electrochemical process may be divided in two parts. In the first step, the electrochemical generation of PH3 on the lead cathode takes place as previously described, while in the second step, mild oxidation of PH3 to H3PO occurs at the anodic surface of the zinc electrode. In agreement with cyclic voltammetry experiments showing an irreversible oxidation wave, PH3 is electrochemically active in the anodic potential range +0.80–1.25 V (vs. Ag/AgNO3, 0.01m in HCN3) and can be therefore oxidized in acidic  ater/ethanol 2:1 solution to H3PO shows the overall electrochemical process resulting in the cathodic reduction of P4 to PH3 and anodic oxidation of PH3 to H3PO (E=+1.24 V vs. Ag/AgNO3, 0.01m in CHCN3).