Artículo de revista
Cyclic voltammetry and digital simulation of the electroreducction of ortho-and meta-nitro aryl 1,4-dihydropyridines
Fecha
1999Registro en:
Boletín de la Sociedad Chilena de Química 44: 067-078
0366-1644
Autor
Bollo Dragnic, Soledad
Núñez Vergara, Luis
Squella Serrano, Juan
Institución
Resumen
Cyclic voltammetry (CV) and digital simulation methods are utilezed to elucidate the mechanism of electrochemical reduction of a series of nitro aryl 1,4-dihydropyridines im protic (aqueous) and mixed media. The experimental voltammograms show different behavior for the reduction of these compounds. In protic media, one cathodic and one anodic peak are observed, but in mixed media a new redox couple appears, indicating a change in the redox mechanism. We have determined that the position of the nitro group (ortho-,meta-) in nitroaromatics directly affects both the electron transfer rate (heterogeneous rate constant, kº10'kº12) and the energetics of the electron transfer (Eº values). According to this study, the splitting observed in the cyclic voltammograms, when aprotic solvent or inhibitors are added to a nitroaromatic aqueous solution, is due to a) a change in the kinetics of the first electron transfer reaction (kº5) from an irreversible to a reversible process, b) to a change in the energetics of the electron transfer and c) to the presence of a dismutation chemical reaction.