The development of highly efficient catalysts for the selective oxidation of styrene to benzaldehyde has attracted great attention in recent years because of its significance in synthetic chemistry. In this study, two different kinds of copper-based metal oxide nanoparticles (NPs), namely, CuO and CuO/Co₃O₄ NPs, were synthesized by a simple and scalable method, and these nanoparticles demonstrated efficient catalytic abilities for the selective oxidation of styrene and its derivatives to the corresponding aldehydes in the presence of tert-butyl hydroperoxide (TBHP) under mild reaction conditions in excellent yields. Importantly, both of the heterogeneous catalysts can be recycled up to five runs while still maintaining their high catalytic activity.

Traditionally important in the pharmaceutical, agrochemical, and synthetic dye industries, CN coupling has proved useful for the preparation of a number of valuable organic compounds. Here, a new method for the direct one-pot reductive CN coupling from carbonyl and aromatic nitro compounds is described. Employing ultrathin platinum nanowires as the catalyst and hydrogen as the reducing agent, N-alkylamines were achieved in high yields. Debenzylation products were not detected after prolonged reaction times. Time-dependent analysis, ReactIR spectroscopy and DFT calculations revealed that the CN coupling proceeded through a different mechanism than traditional “reductive amination.” N-Alkylamines were directly obtained by intermolecular dehydration over platinum nanowires under a hydrogen atmosphere, instead of intramolecular water elimination and imine hydrogenation.

Iron oxide coated platinum nanowires (Pt@Fe₂O₃ NWs) with a diameter of 2.8 nm have been prepared by the oxygen oxidation of FePt NWs in oleylamine. These “cable”-like NWs were characterised by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption fine structure analysis. These Pt@Fe₂O₃ NWs were used as “non-support” heterogeneous catalysts in oxidation of olefins and alcohols. The results revealed that it is an active and highly selective catalyst. Styrene derivatives were tested with molecular oxygen as the sole oxidant, with benzaldehyde successfully obtained from styrene in an absolute yield of 31 %, whereas the use of tert-butyl hydroperoxide as the sole oxidant in the oxidation of alcohols led to yields of more than 80 % of the corresponding ketone or aldehyde. This unsupported catalyst was found to be more active (TOF=96.5 h⁻¹) than other reported Fe₂O₃ nanoparticle catalysts and could be recycled multiple times without any notable decrease in activity. Our findings will extend the use of such nanomaterial catalysts to new catalytic systems.

A novel ultrathin platinum nanowire with uniform length and a diameter of 1.5 nm was synthesized by acidic etching of FePt nanowire in methanol. This nanowire was characterized by high-resolution transmission electron microscopy (HRTEM). X-ray diffraction (XRD) data indicated that the main plane is (111). The ability of this nanowire to catalyze the heterogeneous hydrogenation of nitroaromatics to give the corresponding amines has been investigated. The catalyst showed satisfactory activity in various solvents under mild conditions and showed excellent stability. The catalytic performance was also evaluated in the one-pot reduction of nitroaromatics and amidation with carboxylic acids under a hydrogen atmosphere at 100 °C. These methods for the hydrogenation of nitroaromatics and the direct amidation of nitroaromatics with carboxylic acids are simple, economical, and environmentally benign, and have practical advantages for the synthesis of amines and amides without the production of toxic byproducts.