Multi-electron reduction of nitrobenzene derivatives by an acid-stable NADH analogue via acid-catalysed electron transfer radical-chain reactions

Acid catalysed multi-electron reduction of nitrobenzene derivatives by an acid-stable NADH analogue, 10-methyl-9,10-dihydroacridine, occurs efficiently under mild conditions in the presence of perchloric acid in acetonitrile. Observation of CIDNP spectra as well as detailed kinetic studies on the acid catalysed reduction of nitrobenzene derivatives by AcrH₂ and on the acid catalysed electron transfer from the excited state of [Ru(bpy)₃]²⁺ to nitrobenzene derivatives has revealed that the multi-electron reduction of nitrobenzene derivatives by AcrH₂ proceeds via acid catalysed electron transfer radical-chain reactions in which hydrogen transfer from AcrH₂ to radicals produced by the acid catalysed one-electron reduction of nitrobenzene derivatives is the rate determining propagation step.