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, Pd-II and Au-III from water solutions and to thoroughly disperse them inside the relevant polymer frameworks. Chemical reduction with NaBH4 in water leads to M-0/resin composites, in which size-control of the generated metal nanoclusters is achieved. Catalysts Au-0/MTEMA-DMAA are active in the rapid oxidation of n-butanal to n-butanoic acid by dioxygen under mild conditions in water. Catalysts M-0/MTEMA-DMAA and M-0/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-0 = Au and reach the best level when the very hydrophilic resin poly-(4-vinylpyridine-acrylic acid-N,N'-methylenebisacrylamide) (VAM) is employed.