Synthesis and unexpected electrochemical reaction of p-substituted phenyl diphenylphosphinites

• A series of para-substituted phenyl diphenylphosphinites was synthesized.
• The electrochemistry showed the oxidation of the free electron-pair of the phosphorous atom.
• Either the oxidation or the electrochemical decomposition of the radical cation, Ph2P+(p-R-Ph), was observed.
• An unexpected radical reaction occurred between the radical cation and the ferricinium ion of the internal standard.

A series of para-substituted phenyl diphenylphosphinites [Ph2POPh-p-R, where RH (1), CH3 (2), tBu (3) and Cl (4)] were prepared in near quantitative yields, by the reaction between the desired para-substituted phenol and chlorodiphenylphosphine, in the presence of triethylamine. The electrochemical data obtained for the phosphinite series, showed a one-electron oxidation of the free electron-pair of the phosphorous atom, as well as either the oxidation or the electrochemical decomposition of this phosphinite radical cation. The oxidation peak potential was found to be dependent on the group-electronegativity of the respective para-R-substituent. An unexpected reaction occurred between the electrochemical internal standard, free ferrocene, in its ferricinium ion form and the radical cation of the oxidized diphenyl phosphinite, leading to uncharacteristic electrochemical behaviour.

A series of para-substituted phenyl diphenylphosphinites were prepared, by the reaction between the desired para-substituted phenol and chlorodiphenylphosphine, in the presence of triethylamine. The electrochemical data obtained for this series, showed that both the oxidation and electrochemical decomposition of the phosphinite, is dependent on the group-electronegativity of the respective para-R-substituent. An unexpected reaction of the phosphinite occurred with the electrochemical internal standard ferrocene, in its ferricinium-ion form.Figure optionsDownload as PowerPoint slide