Robert F. Nelson

Electrochemical and Spectroscopic Properties of Cation Radicals III . Reaction Pathways of Carbazolium Radical Ions

Previous work had elucidated the anodic oxidation pathways of carbazole and several N‐substituted derivatives. These studies have now been extended to seventy‐six ring‐substituted carbazoles using electrochemical and spectroscopic techniques to study the reactivity of the various substituted carbazole cation radicals. Generally, it was found that 3, 6, and 9 (N) positions are extremely reactive; if these sites are not blocked by inert substituents the cation radicals generated by electrolytic oxidation react rapidly via coupling‐deprotonation. In some cases, substituents are eliminated from the 3 and 6 positions in the cation radicals followed by coupling to form substituted bicarbazyls. In other cases, relatively stable cation radicals were obtained and their EPR and visible absorption spectra were recorded. It was found that the reactivities of substituted carbazole cation radicals are considerably greater than those of analogous di‐ and triphenylaminium ions due to the planarity of the carbazole aromatic rings.

Anodic oxidation of 5,10-dihydro-5,10-dimethylphenazine

SummaryThe compound 5,10-dihydro-5,10-dimethylphenazine (DMPZ) exhibits two succesive reversible, 1-electron oxidation-reduction steps in acetonitrile and propylene carbonate as solvents. This system has been tested by most of the known diagnostic criteria of electrochemical reversibility and found to adhere to all of them unambiguously. This model system provides a reference for comparison of other multi-stage electrochemical processes.When DMPZ is oxidized in solvents or additives which are strong nucleophiles demethylation accompanies the second stage of oxidation. Since this chemical follow-up reaction occurs in aqueous media it is of significance in the biological redox reactions of N-alkylated phenazines.ZusammenfassungDie Verbindung 5,10-Dihydro-5,10-dimethylphenazin (DMPZ) weist in Acetonitril und Propylencarbonat als Lösungsmittel zwei aufeinanderfolgende reversible einelektronige Oxydations-Reduktions-Stufen auf. Dieses System wurde mit Hilfe der meisten Kriterien für elektrochemische Reversibilität untersucht und in allen Fällen ein eindeutiges Verhalten festgestellt. Das System kann als Bezug zum Vergleich anderer vielstufiger elektrochemischer Prozesse dienen. Wird DMPZ in Lösungsmitteln oder in Gegenwart von Zusätzen, die stark nucleophil sind, oxydiert, so begleitet eine Demethylierung die zweite Stufe der Oxydation. Da diese Reaktion in wäßrigem Medium verläuft, ist sie von Bedeutung bei biologischen Redoxreaktionen von N-alkylierten Phenazinen.