Nanoclustered palladium(0) supported on a gel-type poly-acrylonitrile–N,N-dimethylacrylamide–ethylenedimethacrylate resin: Nanostructural aspects and catalytic behaviour

Synthesis of Ion-Exchange Catalysts by Introduction of Fluorinated Ponytails into Novel Mesoporous Polymers

A novel synthetic procedure for the functionalisation of styrenic cross-linked polymers with perfluorinated acyl chains has been reported. The effective significant grafting of the fluorinated moieties is supported by {¹H}-¹³C and {¹⁹F}-¹³C NMR characterisations. This kind of polymer appears promising as catalytic support for a variety of reactions requiring a highly lipophilic catalyst. Indeed, the improved lipophilicity of the materials resulted in enhanced catalytic properties of the corresponding sulfonic materials in the reaction of esterification of a solution in a vegetable oil of stearic acid with methanol.

Resin-Immobilized Palladium Nanoparticle Catalysts for Organic Reactions in Aqueous Media: Morphological Aspects

An insight into the nano- and micro-structural morphology of a polymer supported Pd catalyst employed in different catalytic reactions under green conditions is reported. The pre-catalyst was obtained by copolymerization of the metal-containing monomer Pd(AAEMA)₂ [AAEMA⁻ = deprotonated form of 2-(acetoacetoxy) ethyl methacrylate] with ethyl methacrylate as co-monomer, and ethylene glycol dimethacrylate as cross-linker. This material was used in water for the Suzuki-Miyaura cross-coupling of aryl bromides, and for the reduction of nitroarenes and quinolines using NaBH₄ or H₂, as reductants. TEM analyses showed that in all cases the pristine Pd(II) species were reduced in situ to Pd(0), which formed metal nanoparticles (NPs, the real active species). The dependence of their average size (2–10 nm) and morphology on different parameters (temperature, reducing agent, presence of a phase transfer agent) is discussed. TEM and micro-IR analyses showed that the polymeric support retained its porosity and stability for several catalytic cycles in all reactions and Pd NPs did not aggregate after reuse. The metal nanoparticle distribution throughout the polymer matrix after several recycles provided precious information about the catalytic mechanism, which was truly heterogeneous in the hydrogenation reactions and of the so-called “release and catch” type in the Suzuki coupling.