The polarography of some substituted azobenzenes in acetonitrile. VI. Proton-donating substituents in the 4-position

Abstract

The polarographic behaviour of azobenzene-4-sulphonic acid and of 4-hydroxyazobenzene in acetonitrile is reported. Four reduction waves were observed in the polarograms of azobenzene-4-sulphonic acid. The first two waves are attributed to the reduction of half of the compound to hydrazobenzene-4-sulphonate ion via azonium species. The third and fourth waves arise from the reduction of the remaining half, present as the azobenzene-4-sulphonate ion, in two one-electron steps. The polarograms of 4-hydroxyazobenzene also exhibit four waves, the first three being poorly defined. Tentative proposals are presented to account for these four waves.