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.