Chitin- and chitosan-anchored methyltrioxorhenium: An innovative approach for selective heterogeneous catalytic epoxidations of olefins

Novel complexes between methyltrioxorhenium (MTO) and natural polysaccharides like chitin and chitosan, or modified chitosan-bearing N-substituted acyl or alkyl pyridine moieties, were synthesized and used for the oxidation of alkenes, including acid-sensitive styrene derivatives, with urea hydrogen peroxide adduct (UHP) as primary oxidant. High conversions and yields of the corresponding epoxides were obtained. Silica–chitosan hybrid composites with increased surface area and mechanical properties were also prepared and used as MTO supports. A correlation on the role played by the different MTO-coordinating ligand sites of supports, on the experimental outcome of olefin catalytic oxidations, is discussed.

Graphical abstractNovel complexes between methyltrioxorhenium (MTO) and natural polysaccharides like chitin, chitosan, modified chitosan, and silica-polysaccharide hybrid composites were synthesized and used as efficient heterogeneous catalysts for the selective oxidation of alkenes, with urea hydrogen peroxide complex (UHP) as primary oxidant.Figure optionsDownload full-size imageDownload high-quality image (75 K)Download as PowerPoint slide