Anionic iron(III) porphyrins immobilized on zinc hydroxide chloride as catalysts for heterogeneous oxidation reactions

This work describes the immobilization of an anionic iron(III) porphyrin (FePor) family on zinc hydroxide chloride (ZHC), a layered hydroxide salt prepared by reacting an aqueous zinc chloride solution with an ammonium hydroxide solution. The FePor immobilization was performed at room temperature under magnetic stirring, under air atmosphere, of each complex ethanol solution and the ZHC solid support suspension. The materials obtained were characterized by X-ray powder diffraction (XRPD), ultraviolet-visible spectroscopy (UV–vis) (solid samples), Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR). The catalytic activity of the solids was investigated in cyclooctene, cyclohexane and n-heptane heterogeneous catalytic oxidation reactions with iodosylbenzene as the oxygen donor. The solid catalyst's reutilization capacity was also investigated and the heterogeneous character of the catalytic process was confirmed. The compounds and the catalytic activity of FePor-ZHC were compared with the synthesis and catalytic activity of the same FePor immobilized on zinc hydroxide nitrate (ZHN). Though the matrixes are similar, the results obtained were exactly the opposite when the selectivity was analyzed.

Figure optionsDownload high-quality image (176 K)Download as PowerPoint slideHighlights
► Immobilization of anionic iron(III) porphyrins on hydroxide salt.
► Catalyst solids for heterogeneous catalysis with reuse capacity.
► Efficiency and selectivity in oxidation reaction.
► Comparison of layered hydroxide salts as support to catalysts.
► Similar layered matrixes, presented opposite selectivity results.