Catalytic oxidation of cyclic hydrocarbons with hydrogen peroxide using Fe complexes immobilized into montmorillonite

Abstract

• Three different Fe complexes immobilized into montmorillonite. • Oxidation of cyclohexane and benzene with H 2 O 2 . • Effect of ligand for oxidation of cyclic hydrocarbons. • Effect of π-π stacking interaction between ligand and substrate. • Catalytic performance for oxidation of benzene in CH 3 CN and H 2 O mixed solvent. [Fe(Ligand) x ] 2+ complexes immobilized into montmorillonite ([Fe(Ligand) x ] 2+ @Mont, Ligand: 2,2′;6′,2′'-terpyridine (x = 2), 1,10-phenanthroline (x = 3), and 2,2′-bipyridine (x = 3)) were prepared by an ion-exchange method whereby cations present within montmorillonite (probably Ca 2+ ) were replaced by [Fe(Ligand) x ] 2+ complexes provided by [Fe(Ligand) x ](ClO 4 ) 2 . The catalytic properties of the species obtained were then investigated in the oxidation of cyclic hydrocarbons, such as cyclohexane and benzene, with H 2 O 2 . The catalytic oxidation of cyclohexane and benzene with H 2 O 2 over [Fe(Ligand) x ] 2+ @Mont catalysts proceeded, and the desired alcohols were obtained as the main reaction products, whereas no catalytic activity was displayed by neat montmorillonite. Regardless of the reaction conditions, [Fe(terpy) 2 ] 2+ @Mont (terpy stands for 2,2′;6′,2′'-terpyridine) exhibited the best catalytic performance in the oxidation of the mentioned substrates by H 2 O 2 , among all the catalysts tested.