Recently Fe3O4@silica sulfuric acid as an efficient nanomagnetically recyclable solid acid catalyst
has been synthesized and used in organic transformations. Magnetic nanoparticles were synthesized by simple
co-precipitation of FeCl2.4H2O and FeCl3.6H2O in ammonia solution. Then, after addition of tetraethyl orthosilicate
in ammonia solution, silica was formed on the surface of magnetite nanoparticles. Finally, the catalyst has
been prepared by the functionalization of silica-coated magnetic nanoparticles (Fe3O4@SiO2) using chlorosulfonic
acid. The catalyst was characterized by Fourier transform-infrared (FT-IR) spectrometry, X-ray diffraction
(XRD) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating-
sample magnetometry (VSM) and thermo gravimetric analyses (TGA). Nano-Fe3O4@silica sulfuric acid
was easily recovered from the reaction mixtures by an external magnet and reused several times with no significant
decrease in its catalytic activity. In this review, preparation, characterization and applications of this catalyst
in organic synthesis has been discussed.
Keywords: Fe3O4@Silica sulfuric acid, solid acid, heterogeneous catalyst, magnetic nanoparticles, organic reactions, green chemistry.
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