Electrochemical synthesis of heterocyclic compounds. Part 6. The redox behaviour of the formazan–tetrazolium salt system in acetonitrile

Abstract

The synthesis in quantitative yield of 2,3,5-triaryltetrazolium salts by anodic oxidation of formazans is described. The redox behaviour of the 1,3,5-triphenylformazan–2,3,5-triphenyltetrazolium perchlorate system was studied in detail using electroanalytical techniques. It is concluded that two-electron oxidative cyclisation of formazan to tetrazolium salt occurs through an e-c-P-e-(d) mechanism, using the nomenclature of Andrieux and Savéant. The reduction of the tetrazolium salt to the formazan goes by opposite mechanistic pathways (e-P-c-e) to those for the electrochemical oxidation of formazan.