Covalent Immobilization of Polyoxotungstate on Alumina and Its Catalytic Generation of Sulfoxides

The structural and chemical stabilities of immobilized polyoxometalate (POM)‐containing catalysts are crucial factors for their industrial application. An alumina supported POM catalyst is prepared by using a facile condensation reaction between the trilacunary POM Na 12 [α‐P 2 W 15 O 56 ] ⋅ 24 H 2 O (P 2 W 15 ) and the hydroxy groups on the surface of γ‐Al 2 O 3 spheres under acidic conditions. The heterogeneous catalyst P 2 W 15 −Al 2 O 3 is characterized by a wide variety of techniques and shows excellent stability and highly efficient reactivity and selectivity for the oxygenation of thioethers to sulfoxides, which are a very useful intermediate in organic synthesis and the industrial preparation of drugs. Furthermore, P 2 W 15 −Al 2 O 3 can be recycled and reused at least ten times without any observable loss of its catalytic efficiency, mainly due to the covalent immobilization and high dispersion of P 2 W 15 on the γ‐Al 2 O 3 surface.