ELECTROCHEMICAL-BEHAVIOR OF NITROINDOLES - OXIDATIVE ELECTROPOLYMERIZATION AND REDUCTION OF THE NITRO-GROUP OF POLYMERIZED AND NON-POLYMERIZED 4-NITRO AND 5-NITROINDOLE

Nitroindoles give polymer films after oxidative electropolymerization on a Au rotating-disc electrode in acetonitrile. Films of poly(4-nitro indole) and poly(5-nitroindole) were grown potentiostatically at poten tials where electrodissolution of Au substrate occurs simultaneously w ith the electropolymerization. The films are electroactive. Their cycl ic voltammograms in acetonitrile present an immense cathodic peak corr esponding to the reduction of the nitro group. On transfer to aqueous electrolyte, films of poly(5-nitroindole) show well-defined reduction peaks, while those of poly(4-nitroindole) show ill-defined peaks. The reduction of the nitro group of the monomers has also been studied. Ni troindoles show the usual behaviour of aromatic nitro compounds both i n aqueous solutions and in acetonitrile. Finally, it was found that un derpotentially deposited layers of Pb and Tl on Au and Pt have a marke d influence on the catalytic activity and selectivity of these electro des for the nitro group electroreduction.