R. Andruzzi, A. Trazza, P. Bruni
Apr 10, 1974
Citations
0
Influential Citations
5
Citations
Journal
Journal of Electroanalytical Chemistry
Abstract
Summary The electrochemical reduction of 1,1′-dioxy-2,2′-diphenyl-Δ 3.3′ -bi-3H-indole (I) in dimethylformamide (DMF) solution has been studied at mercury and platinum electrodes in the presence and absence of protonating agents. Voltammetric, controlled-potential coulometric, e.s.r. and u.v. spectroscopic techniques were employed in the study. In an aprotic medium (DMF with tetraethylammonium perchlorate as supporting electrolyte) the reduction proceeds in two reversible one-electron steps: first to a very stable anion radical, identified by e.s.r. spectrum, and then to the di-anion. In the presence of a protonating agent (BH) (p K BH d >15) the second reduction step shifts to more positive potentials, while the first is unchanged. With a large amount of (BH) a single two-electron step is observed, the corresponding 1,1′-di-hydroxy-2,2′-diphenyl-3,3′-bi-indole (II) being the reduction product. In the presence of a stronger protonic source (AH) (p K AH d K AH d values of acids investigated. A multi-step scheme suggested for the electrochemical reduction of (I) explains the various experimental results obtained.