Aluminosilicate obtained by sol-gel process as support for an anionic iron porphyrin: Development of a selective and reusable catalyst for oxidation reactions

An anionic iron(III) porphyrin was immobilized on a synthetic aluminosilicate obtained by the sol-gel process and used as catalyst in the oxidation of organic substrates. Aluminosilicate was prepared by modi. cation of a method previously described in the literature, using an ethanol/water solution of AlCl3 center dot 6H(2)O and Si(OC2H5)(4) (TEOS). Iron(III) porphyrin immobilization was carried out using magnetic stirring and reflux, and a good immobilization rate (88%) was obtained. Immobilization of a neutral iron(III) porphyrin on the solid was also tested, without success. The obtained materials were characterized by ultraviolet-visible and infrared spectroscopies, X-ray diffraction, TGA analysis, nitrogen absorption, and electron paramagnetic resonance (EPR). The catalytic activity of the immobilized iron(III) porphyrin was evaluated in the oxidation of cyclooctene, cyclohexane, and n-heptane, using iodosylbenzene as the oxygen donor. The results obtained in the present study show that the novel immobilized catalyst is a promising system for efficient and selective oxidation reactions. Besides that, the stable interaction between the iron(III) porphyrin complex and the support enables reuse of the heterogeneous catalyst. (C) 2009 Elsevier B. V. All rights reserved.