writer：Linbin Feng, Jianli Wang*, Liang Chen, Meizhen Lu, Zhi Zheng, Ren Jing, Hualiang Chen, Xianbo Shen
keywords：heterogeneous catalysis; microreactors; Montanari oxidation; nanoparticles; Pickering emulsions; phase-transfer catalysis
source：期刊
Issue time：2015年
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.关键词