Covalent Immobilization of Imidazolium Cations Inside a Silica Support: Palladium‐Catalyzed Olefin Hydrogenation

Abstract

Mesoporous organosilica materials with different contents of bistrialkoxysilyl imidazolium salts in the framework were synthesized by a one‐step synthesis. Textural characterization of the materials confirmed that the morphology and surface properties of the imidazolium‐bridged organosilicas depended critically on the amount of organic groups in the framework, whereas solid‐state NMR characterization showed that the imidazolium fragments were integrated covalently into the framework. Further reaction of these materials with Pd(OAc)2, followed by reduction with NaBH4 yielded palladium nanoparticles stabilized in the mesoporous organosilicas. The stabilizing effect of the imidazolium cations and the mesostructure contributed to the high activity, selectivity, and stability of the palladium nanoparticles and allowed olefin hydrogenation under mild reaction conditions.

Electrostatic immobilization of phosphomolybdic acid on imidazolium-based mesoporous organosilicas for catalytic olefin epoxidation

“…N-(3-Propyltrimethoxysilane)imidazole and 1,3-di(3propyltrimethoxysilane)imidazolium iodide (1) were synthesized according to literature procedures [33,34]. PMO-ILs with various imidazolium cation contents were prepared according to Wang et al [33]. Typically, P123 (2 g) was dissolved in 2 mol/L HCl (60 ml).…”

“…Designing and preparing efficient POM-based heterogeneous catalysts for selective oxidation and epoxidation remain an attractive research area. Periodic mesoporous organosilica containing embedded imidazolium cations (PMO-IL) was recently synthesized by controlling the hydrolysis and co-condensation of a disilylated imidazolium based ionic liquid (IL) [29][30][31][32][33][34]. Such materials combine the advantages of the mesoporous material and IL.…”

“…Various recent studies showed that PMO-IL could serve as a host for dispersing and stabilizing noble metal species/particles. The resulting materials were highly active and stable heterogeneous hybrid catalysts for coupling reactions [29,30], aerobic oxidation of alcohols [31,32], and olefin hydrogenation [33].…”

Pd Nanoparticles Immobilized on Graphene Oxide/Silica Nanocomposite: Efficient and Recyclable Catalysts for Cross‐Coupling Reactions

“…Among carbon materials, graphene oxide (GO) has become one of the most studied carbon based materials combining high surface area, high thermal, chemical and mechanical stability. Because of these properties, GO has been explored extensively as a catalyst support for metal nanoparticles . Generally, GO is obtained by oxidation of natural graphite using strong oxidizing agents, this process produces single or few layer of oxide graphene.…”

Sonochemical synthesis of PdO@silica as a nanocatalyst for selective aerobic alcohol oxidation

“…However, these methods usually require long reaction time and complicated steps to modify the surface. Furthermore, non-uniform decoration with metal NP is observed due to the imperfect surface modification [2,17,18].…”