Ceria/Polymer Hybrid Nanoparticles as Efficient Catalysts for the Hydration of Nitriles to Amides

We report the synthesis of ceria/polymer hybrid nanoparticles and their use as effective supported catalysts for the hydration of nitriles to amide, exemplified with the conversion of 2-cyanopiridine to 2-picolinamide. The polymeric cores, made of either polystyrene (PS) or poly(methyl methacrylate) (PMMA), are prepared by miniemulsion copolymerization in the presence of different functional comonomers that provide carboxylic or phosphate groups: acrylic acid, maleic acid, and ethylene glycol methacrylate phosphate. The functional groups of the comonomers generate a corona around the main polymer particle and serve as nucleating agents for the in situ crystallization of cerium(IV) oxide. The obtained hybrid nanoparticles can be easily redispersed in water or ethanol. The conversion of amides to nitriles was quantitative for most of the catalytic samples, with yields close to 100%. According to our experimental observations by high-performance liquid chromatography (HPLC), no work up is needed to separate the product from unreacted substrate. The substrate remains absorbed on the catalyst surface, whereas the product can be easily separated. The catalysts are shown to be recyclable and can be reused for a large number of cycles without loss in efficiency.