On the Electron-Proton-Electron Mechanism for 1-Benzyl-1,4-dihydronicotinamide Oxidations

Article abstract of DOI:10.1021/ja00220a042

The reaction of 1-benzyl-1,4-dihydronicotinamide (BNAH) with serveral ferrocenium (Fc⁺) salts in aqueous propanol was studied.The mechanism was shown to involve electron-proton-electron transfer with rate-limiting electron transfer from BNAH to Fc⁺.From the rate constants and E⁰(BNAH/BNAH^.+) was estimated to be 0.89 V (SCE).The electrochemistry of BNAH was investigated in order to evaluate a previously determined E⁰(BNAH/BNAH^.+).A reconsideration of the literature data for (non-DDQ) quinone oxidations of reduced nicotinamide adenine dinucleotide (NADH) in water and BNAH in CH3CN shows that the data are consistent with a hydride-transfer mechanism and inconsistent with an electron-proton-electron mechanism involving free NADH^.+.A mechanismin which the hydride is transferred by electron-proton-electron transfer within one complex cannot be excluded.