Reduction of dioxygen by an NADH model compound and 1,1′-dimethylferrocene catalysed by acids in homogeneous and heterogeneous systems

Abstract

An acid-stable NADH model compound, 10-methyl-9,10-dihydroacridine (AcrH₂) and 1,1′-dimethylferrocene [Fe(C₅H₄Me)₂] are oxidized by dioxygen in the presence of HClO₄ in acetonitrile and water. The acid-catalysed two-electron and four-electron reductions of dioxygen by AcrH₂ and [Fe(C₅H₄Me)₂], respectively, take place more efficiently in the heterogeneous systems using solid acid catalysts [alumina, silica–alumina, HY-type zeolite, and solid superacids (ZrO₂ and Fe₂O₃ treated with H₂SO₄)] activated by calcination at various temperatures. Mechanisms of both the homogeneous and heterogeneous reduction of dioxygen by AcrH₂ and [Fe(C₅H₄Me)₂] are discussed.