Generation of size-controlled palladium (0) and gold (0) nanoclusters inside the nanoporous domains of gel-type functional resins. Part II: Prospects for oxidation catalysis in the liquid phase

Moderately cross-linked co-polymers of N,N-dimethylacrylamide (DMAA), 2-(methylthio)ethyl methacrylate (MTEMA)and N,N'-methylenebisacrylamide proves to be effective macromolecular ligands able to extract, PdII and AuIII from water solutions and to thoroughly disperse them inside the relevant polymer frameworks. Chemical reduction with NaBH4 in water leads to M°/resin composites, in which size-control of the generated metal nanoclusters is achieved. Catalysts Au°/MTEMA-DMAA are active in the rapid oxidation of n-butanal to n-butanoic acid by dioxygen under mild conditions in water. Catalysts M°/MTEMA-DMAA and M°/C (M = Au, Pd) are active and moderalely chemoselective in the oxidation of n-butanol to n-butanal under the same conditions. Activity and chemoselectivity are positively affected by the co-presence of the two metal centres and for M°= Au and reach the best level when the very hydrophilic resin poly-(4-vinylpyridine-acrylic acid-N,N'-methylenebisacrylamide) (VAM) is employed.