Epoxidation of Alkenes with Molecular Oxygen Catalyzed by Immobilized Co(acac)₂ and Co(bpy)₂Cl₂ Complexes within Nanoreactors of Al‐MCM‐41

Abstract

Cobalt complexes with different ligands such as bipyridine, and acetylacetonate were immobilized within nanoreactors of Al-MCM-41, designated as Co(acac)2/Al-MCM-41 and Co(bipy)22+/Al-MCM41. The immobilized complexes were characterized by XRD, N2-adsorption desorption, FT-IR and UV-Vis techniques. It was found that Co(bipy)22+/Al-MCM41 and Co(acac)2/Al-MCM-41 successfully catalyze the oxidation of norbornene, styrene, cis-stilbene, trans-stilbene, and cyclohexene with 68% to 100% conversion and 41% to 90% selectivity toward the corresponding epoxides. No desorption was observed during the course of reactions.

Recent applications of nanoparticles in organic transformations

“…45 Commonly, epoxidation of alkenes has been carried out in the presence of molecular oxygen. [46][47][48] However, it has been proposed that using TiO 2 supported on gold nanoparticles as a catalyst, is a much more efficient method. Deoxygenation reactions provide functionalized alkenes, sulfides, and N-heteroarene products in high yields for a variety of reactants.…”

Co(acac)2-Catalyzed Allylic and Benzylic Oxidation by tert-Butyl Hydroperoxide

“…20 In particular, cobalt(II) acetate and other cobalt compounds in homogeneous and heterogeneous forms are effective for the allylic and benzylic oxidation of unsaturated steroidal substrates. 21 Recently, cobalt(II) acetylacetonate [Co(acac) 2 ] has been used successfully in the catalytic oxidation of aromatic and α,β-unsaturated aldehydes to carboxylic acids, 22 the epoxidation of alkenes, 23 and in radical polymerization. 24 Herein we report our findings in the area of allylic and benzylic oxidation with tertbutyl hydroperoxide (TBHP) in the presence of Co(acac) 2 as a catalyst.…”