In this report, Fe3O4 nanoparticles are modified for the first time with graphene quantum dots (GQD) and used for the stabilization of PdCu bimetallic nanoparticles. The new magnetic compound, PdCu@GQD@Fe3O4, is characterized by different methods such as SEM, high‐resolution (HR)‐TEM, energy‐dispersive X‐ray spectroscopy (EDS) mapping, XRD, and X‐ray photoelectron spectroscopy (XPS). This material is applied as an efficient catalyst for the Sonogashira reaction of aryl iodides, bromides, and chlorides in toluene or N,N‐dimethylacetamide at 60–110 °C in very high yields with 0.3 mol % of Pd loading. According to different tests, such as polyvinylpyridine poisoning, hot filtration, and kinetic studies, this catalyst works under heterogeneous conditions. By magnetic separation of the catalyst, it can be recycled for six consecutive runs with only a small decrease in activity without appreciable structural modification of the reused catalyst, which is characterized by TEM and XPS.

Copper ferrite and palladium nanoparticles assembled on silica microparticles are prepared successfully and characterized by scanning electron microscopy, transmission electron microscopy, electron‐dispersive X‐ray analysis, X‐ray diffraction, thermogravimetric analysis, atomic absorption spectroscopy, and infrared studies. The catalyst is applied effectively for the Sonogashira coupling reaction of aryl iodides and bromides under heterogeneous and phosphine‐free reaction conditions. The reactions proceed at 50 °C with a low loading of palladium catalyst. The magnetically recoverable catalyst is recycled successfully for five consecutive runs with very small drops in catalytic activity.

Abstract:Novel silica supported gold and copper ferrite nanoparticles (NPs) have been synthesized, characterized and used as a separable dual catalyst in Sonogashira type reaction. These Au·CuFe2O4@Silica NPs show a high efficiency as catalyst in the alkynylation not only of aryl iodides but also aryl bromides. By using only 0.5 mol% loading and t-BuOK as base in N,Ndimethylacetamide as solvent, aryl iodides react at 115 ºC in 1 d, whereas for aryl bromides the cross-coupling takes place at 130 ºC in 2 d. The catalyst can be successfully recycled using an external magnet for four consecutive runs.

A magnetic bimetallic catalyst is prepared, characterized and used in the Sonogashira reaction of aromatic halides with acetylenes.

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