Metal-doped epoxy resins: Easily accessible, durable, and highly versatile catalysts

Abstract

Thermosetting epoxy resins, such as the triglycidyl derivative of 4-aminophenol, can be polymerized using molybdenum, palladium, or rhodium complexes as initiators. The resulting metal-doped materials proved to be efficient catalysts for epoxidation, carbon–carbon coupling, hydrogenation, and hydroformylation reactions. Propylene oxide yields of around 50% were obtained in the epoxidation of propylene with tert-butyl hydroperoxide as the oxidant, and biphenyl yields of ⩾98% were observed in the Suzuki coupling of iodobenzene with phenylboronic acid. Almost quantitative conversions were accomplished in the hydrogenation of ethyl crotonate, ethyl cinnamate, and croton aldehyde, whereas aldehyde yields of around 16% were obtained in the hydroformylation of 1-octene. Organic–inorganic hybrid catalysts can be obtained in a convenient one-step procedure by the addition of inorganic components to the liquid resins and subsequent polymerization. Different metal species can be combined in one thermoset matrix, affording multifunctional catalysts that can be us in various catalytic liquid-phase transformations. Quantification of metal traces in the reaction mixtures by metal enrichment and atomic spectroscopy demonstrated very low metal losses of the catalysts. The catalysts can be simply recovered by filtration and reused without reconditioning while maintaining stability, activity, and selectivity.