Direct covalent attachment of Mn(iii) salophen complex to the hydroxyapatite-encapsulated γ-Fe2O3 nanocrystallites: an efficient magnetic and reusable catalyst for oxidation of alcohols

Abstract

In the present work, the highly efficient oxidation of alcohols catalyzed by manganese(III) salophen acetate, [Mn(salophen)OAc], supported on hydroxyapatite coated magnetite nanoparticles, HAp–Fe₂O₃, is reported. First, the HAp–Fe₂O₃ nanoparticles were modified with 5-chloromethyl-2-hydroxybenzaldehyde and then using 1,2-diamino benzene, 2-hydroxybenzaldehyde and Mn(CH₃COO)₂·4H₂O, [Mn(salophen)OAc] was synthesized and attached to the support via covalent linkages. The prepared catalyst was characterized by FT-IR spectroscopy, X-ray diffraction, diffuse reflectance UV-Vis spectrophotometry and scanning electron microscopy. This new heterogeneous catalyst was used for efficient oxidation of alcohols with NaIO₄ at room temperature. This new heterogeneous catalyst is of high reusability in the oxidation reactions, in which the catalyst was reused several times without significant loss of its catalytic activity.