Electrochemical properties of nicotinamide derivatives in aqueous solution - Part IV. Oxidation of N1 -alkyl-1,4-dihydronicotinamides

Philippe Leduc (1) , Daniel R. Thévenot (2, 1)

1 LEB - Laboratoire d'Energétique Biochimique
2 CEREVE - Centre d'Enseignement et de Recherche Eau Ville Environnement

The electrochemical reduction of nicotinamide—adenine-dinucleotide (NAD+) and model compounds has been extensively studied1-3 ; on the other hand very few papers have been published on the electrochemical oxidation of nicotinamide—adenine-dinucleotide reduced (NADH) in aqueous solution. Haas4 reported the occurrence of an oxidation wave of NADH at pH 8.6 at rotating platinum and glassy carbon disk electrodes (with respective half-wave potentials 0.90 ± 0.02 and 0.67 ± 0.03 V vs. NHE); macroscale electrolyses lead to NAD+ by a two-electron oxidation4'5. In this paper we shall present the features of the electrochemical oxidation of model compounds of NADH, namely Ni-benzyl-and NL-propyl-l,4-dihydronicotinamide (NBzNH and NPrNH) in aqueous solution, buffered within a large pH range; a possible mechanism is deduced from these data. Extensive studies have shown the occurrence of a "primary acid modification" of aqueous NADH solutions or its models below pH 7 (ref. 6); the common explanation put forward is a saturation of the 5-6 double bond in the pyridinic ring, the u.v. absorption band being shifted from 355 to 290 nm. Therefore the results and discussions presented here only concern the pH range 7 to 13. Experimental All products used were prepared in this laboratory, according to published methods, namely NBzNTP (ref. 7), NBzNH and NPrN+Br~ (ref. 8), NPrNH (ref. 9). The purity and concentration of the freshly prepared aqueous solutions were checked by u.v. spectrophotometry with a Cary 14 apparatus. Drop-time controlled portography and voltammetry were carried out with Tacussel equipment (PRT 500 LC\ Servovit 9 B, S6 RZ millivoltmeter) and a Sefram "Luxy trace" bigalvanometric recorder. A Tacussel IG 4-100 electronic integrator was used for coulometry. At the beginning of all macroelectrolyses a Fontaine A 60 power-supply was connected between the counter-electrode and the generator. All aqueous solutions were thermostated at 25.0 ± 0.1°C during the experiments.

Domaines: Chimie; Chimie analytique; Chimie organique; Biochimie [q-bio.BM]

Philippe Leduc, Daniel R. Thévenot. Electrochemical properties of nicotinamide derivatives in aqueous solution - Part IV. Oxidation of N1 -alkyl-1,4-dihydronicotinamides. Electroanalytical Chemistry and Interfacial Electrochemistry, 1973, 47, pp.543-546. ⟨hal-01179282⟩