Catalysts Based Upon Organoclay with Tunable Polarity and Dispersion Behavior: New Catalysts for Hydrogenation, C-C Coupling Reactions and Fluorous Biphase Catalysis

Spherical Pd nanoparticles (2-8 nm) were immobilized on the nanometer-scaled platelets of montmorillonite (MMT) by means of cation exchange of Pd2+ for Na+ followed by chemical reduction. The resulting Pd catalysts were readily dispersible in water and polar solvents. Polarity design and thus, variation of the dispersion behavior was achieved by subsequent organophilic MMT modification involving cation exchange with N-alkyl and N-perfluoroalkylethyl pyridinium cations. This allowed for easy catalyst dispersion in a wide range of organic solvents. According to characterization by TEM, EDXS, AAS and WAXS the nanoparticle formation did not destroy the superstructure of unmodified and organophilic MMT. Catalysts were applied to hydrogenation, Suzuki-Miyaura C-C coupling and fluorous biphase catalysis. The tunable dispersion behavior of MMT catalysts was successfully employed to guarantee easy catalyst recovery and recycling.