Novel magnetite-sulfuric acid (Fe3O4 center dot SO3H) magnetic nanoparticles were prepared by the direct reaction of chlorosulfonic acid with magnetite nanoparticles, and characterized by IR spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. The catalytic activity of the Fe3O4 center dot SO3H nanoparticles in the reaction of 2-naphthol with aryl mono-, di- and trialdehydes was examined, and these catalysts were shown to exhibit remarkable catalytic performance in the solvent-free synthesis of mono-, bis-, and tris-14H-dibenzo[a,j]xanthen-14-ylarenes. The catalyst retained its activity for several cycles.
