Monooxygenatation of Alkanes and Aromatics Catalyzed by Nonheme-Iron Complex/Hydroquinone/O₂ Systems

Abstract

Monooxygenation of aromatics, alicyclic and linear alkanes with molecular oxygen is catalyzed by nonheme iron complexes in the anhydrous organic solvents in the presence of hydroquinones as electron and proton donors. Iron complexes are prepared in situ by stirring FeCl₃, pyrocatechol, and pyridine (mole ratio is 1:1:2) in acetonitrile or in pyridine. Isolated catecholatoiron complex is also used. Catalytic activity is greatly dependent on the kinds of hydroquinone and increases in the order of 2,5-di-t-butyl- ≈ t-butyl->methyl->H-hydroquinone. Non-substituted hydroquinone hardly exhibits activity, and the activity is controlled by the oxidation potential and steric effect of hydroquinones.