Detection of a radical cation of an NADH analogue in two-electron reduction of a protonated p-quinone derivative by an NADH analogue

(Chemical Equation Presented) An electron-transfer pathway is preferred to a direct hydride-transfer pathway in two-electron reduction of protonated 1-(p-tolylsulfinyl)-2,5-benzoquinone by the NADH analogue 10-methyl-9,10- dihydroacridine, as has been demonstrated for the first time by ESR detection of the resulting radical cation of the acridine derivative (see picture).