Cyclic voltammetry of nitrophenyl N-glycosides on mercury electrode

• Published in: Journal of physical organic chemistry 2011-12, Vol.24 (12), p.1229-1234
• Main Authors: Gubica, Tomasz, Stroka, Jadwiga, Temeriusz, Andrzej, Kańska, Marianna
• Format: Article
• Language: English
• Subjects: cyclic voltammetry; electroreduction; mercury electrode; nitrophenyl N-glycosides
• ISSN: 0894-3230; 1099-1395
• DOI: 10.1002/poc.1854

Ten nitrophenyl N‐glycosides have been studied electrochemically in neutral (at pH 7) water–organic solutions by cyclic voltammetry using static mercury drop electrode. For all compounds under investigation the two electrochemical processes have been observed: the four‐electron irreversible reduction of their nitro groups to the corresponding phenylhydroxylamine derivatives, as well as the two‐electron quasi‐reversible process between phenylhydroxylamine and nitroso derivatives. For three compounds the additional electrochemical processes have been also observed, which can be connected with the formation of azoxybenzene derivatives. The potentials of both redox processes: a two‐electron quasi‐reversible RNHOH/RNO (Ef) and four‐electron irreversible RNO2/RNHOH (Epc(I)) systems have been determined and discussed according to crystal structures of selected compounds. Ef and Epc(I) depended strongly on the positive mesomeric effect (caused by glycosidic nitrogen atom), as well as on the intramolecular hydrogen bond between electroactive nitro group and the hydrogen atom at the glycosidic atom observed in N‐o‐nitrophenyl‐2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosylamine. Moreover, the chirality of selected reactants has had the pronounced effect on the Epc(I). Copyright © 2011 John Wiley & Sons, Ltd. This paper describes studies of the influence of the second substituent (different sugar moieties) at the nitrobenzene ring on the electrode potentials of ten nitrophenyl N‐glycosides. The potentials of both observed redox processes: two‐electron quasi‐reversible RNHOH/RNO (Ef) and four‐electron irreversible RNO2/RNHOH (Epc(I)) systems have depended strongly on the positive mesomeric effect (caused by glycosidic nitrogen atom), as well as on the other effects, e.g. intramolecular hydrogen bond, steric hindrance, and chirality.