Catalytic activity of Jacobsen catalyst encapsulated in an alumina matrix by the sol–gel process

This work describes optimized conditions for the preparation of the Jacobsen catalyst entrapped in alumina in the powder form. The hybrid material was obtained by a non-hydrolytic sol–gel route, through condensation of aluminum chloride with diisopropylether in the presence of the Jacobsen catalyst. The material was characterized by X-ray diffraction (XRD), surface area analysis, thermogravimetric analysis (TG), differential thermal analysis (DTA), and ultraviolet–visible spectroscopy. The ultraviolet–visible absorption spectrum of the entrapped catalyst displayed the typical bands of the Jacobsen catalyst, showing that the structure of the complex was preserved in the hybrid material. This material efficiently catalyzed the oxidation of (Z)-cyclooctene, styrene, and cyclohexane by different oxidants (iodosylbenzene, iodosylbenzenediacetate, 3-chloroperoxybenzoic acid, tert-butyl hydroperoxide, hydrogen peroxide 30 and 70 wt.%) when compared with the catalyst in homogeneous solution. These results show the importance of the non-hydrolytic alumina matrix in making the Jacobsen catalyst more active, avoiding its destruction and/or the formation of dimeric specie.

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