An efficient maghemite–ZnO nanocatalyst has been synthesized via a simple coprecipitation method, where ZnO nanoparticles are uniformly decorated on the maghemite core and characterized by XRD, SEM-EDS, ICP-AES, XPS, TEM, HRTEM, and Mössbauer spectroscopy; maghemite nanoparticles are in the typical size range 10–30 nm with ultrasmall (3–5 nm) ZnO nanoparticles. A competent and benign protocol is reported for various organic transformations, namely, transesterification, amidation, and O-acylation reaction in good to excellent yields (75–97%) using magnetically separable and reusable maghemite–ZnO nanocatalyst.

Efficient and general protocols for the O-tert-boc protection and O-arylation of phenols were developed in this paper using a recyclable magnetic Fe3O4-Co3O4 nanocatalyst (Nano-Fe-Co), which is easily accessible via simple wet impregnation techniques in aqueous mediums from inexpensive precursors. The results showed the catalysts were well characterized by XRD (X-ray Diffraction), ICP-AES (Inductive Coupled Plasma Atomic Emission Spectroscopy), TEM (Transmission Electron Microscopy), TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry) and XPS (X-ray Photoelectron Spectroscopy). The O-tert-boc protection and O-arylation of phenols was accomplished in good to excellent yields (85–95%) and the catalyst was reusable and recyclable with no loss of catalytic activity for at least six repetitions.

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Montmorillonite (K10) loaded on magnetite silica-coated nanoparticles was made using simple co-precipitation methods.