TEMPO Supported on Magnetic C/Co-Nanoparticles: A Highly Active and Recyclable Organocatalyst

TEMPO was grafted on graphene‐coated nanobeads with a magnetic cobalt core by using a general applicable “click”‐chemistry protocol. The new heterogeneous CoNP–TEMPO emerged as a highly active catalyst for the chemoselective oxidation of primary and secondary alcohols using bleach as terminal oxidant. The outstanding stability of the C/Co nanoparticles enables the nanopowder to tolerate several TEMPO‐mediated iterative oxidation reactions without any significant loss in catalyst activity. Furthermore, the excellent magnetic properties enable the rapid separation and quantitative recycling of CoNP–TEMPO out of the reaction mixture by simple magnetic decantation. The recovered nanoparticles can be subsequently reused without any further purification. TEMPO was immobilized on carbon‐coated cobalt nanoparticles via click chemistry resulting in a remarkably stable and recyclable organocatalyst (see graphic) which maintains its high reactivity throughout several iterative oxidation reactions. The quantitative recovery of the catalyst succeeds plainly by applying an external magnet followed by decantation of the reaction mixture.