A Green Strategy to Enhance a Liquid-Liquid Heterogeneous Reaction with a Magnetic Recyclable Pickering Emulsion.

This work described a general strategy to enhance a typical organic-aqueous heterogeneous green oxidation reaction by introducing surface tunable magnetic nanoparticles into liquids to form a controllable Pickering emulsion. We synthesized cross-linked polystyrene (PS)-covered Fe₃O₄ nanoparticles grafted with different N-alkyl imidazoles and systematically discussed the effect of surface properties on the formation of emulsions. By loading such particles, the dichloromethane-water-based 2,2,6,6-tetramethylpiperidine-1-oxyl-mediated Montanari oxidation system was converted from the unstable millimeter-scale dispersion into a stable micrometer-scale emulsion, which significantly reduced the reactant transfer distance and resulted in a significantly high overall reaction rate. This reaction efficiency is elucidated in terms of unique properties inherent in an emulsion, including the self-assembly of Fe₃O₄/PS and Fe₃O₄/PS[im-C _n]Cl ( n=1, 4, 6, and 10) nanoparticles, well ensuring a large specific surface area of the water-oil interface. [ABSTRACT FROM AUTHOR]