A STUDY OF THE ANODIC VOLTAMMETRIC PROPERTIES OF TRIPHENYLPHOSPHINE

Although several bulk electrolysis studies of the electro-oxidation of triphenylphosphine (Ph(3)P) have been published, and its products, tr iphenilphosphonium salts and triphenylphosphine oxide are well charact erized, only scant and qualitative information on its anodic voltammet ric properties is available. The voltammetric behavior of Ph(3)P in ac etonitrile solutions, using vitreous carbon anodes, is studied in deta il. Results using dimethylformamide solvent with vitreous carbon and p latinum anodes are also reported and compared. In ACN solution, with v itreous carbon anodes, the radical cation formed in the first electron transfer step reacts with residual water. A one-electron, diffusional , EC(irrev) voltammetric peak is observed for the anodic electro-oxida tion of Ph(3)P at sweep rates higher than 0.020 V s(-1). The effect of a second charge transfer is experimentally observed at lower sweep ra tes. Implicit finite difference-simulated voltammograms are calculated to reproduce the results. The protonation reaction of Ph(3)P is demon strated to be slow in the time scale of cyclic voltammetry, but it is catalyzed by the Pt anode, where Ph(3)P adsorption is also observed. P h(3)P is voltammetrically electro-oxidated in DMF in a two-electron E( 1)C(1)E(2) process with E(2) less than or equal to E(1). Diffusion coe fficients for Ph(3)P, based on these anodic voltammetric measurements, which agree with the known polarographic values, are given for the fi rst time.