Water-Dispersible, Magnetically Recyclable Heterogeneous Cobalt Catalyst for C-C and C-N Cross-Coupling Reactions in Aqueous Media.

A cobalt catalyst supported on an iron oxide core, denoted as γ-FeO@PEG@THMAM-Co, has been prepared and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray mapping, thermogravimetry differential thermogravimetry, vibrating sample magnetometry, and inductively coupled plasma. Polyhydroxy end groups in the shell make the catalyst particles dispersible in water, allowing Hiyama, Suzuki, and C-N cross-coupling reactions of aryl iodides and bromides. The catalyst could be recovered by magnetic decantation and reused for at least five successive runs with a negligent decrease in its activity or changes in its morphology. Water as a solvent without requiring additives, surfactants, or organic co-solvents, as well as an abundant and low-cost cobalt catalyst combined with facile recovery, low leaching, and scalability, provides an environmentally and economically attractive alternative to established palladium-catalyzed C-C and C-N coupling reactions.