Magnetically separable modified sulfuric acid (CuFe2O4@SiO2-OSO3H): Preparation, characterization and catalytic application for the synthesis of 1,8-dioxo-octahydroxanthenes

A nanomagnetic acidic catalyst (CuFe2O4@SiO2-OSO3H) was prepared by the chemical anchoring of sulfuric acid onto the surface of modified CuFe2O4 magnetic nanoparticles and characterized using FTIR, SEM, EDX, and VSM techniques. The results confirmed that the sulfuric acid is well dispersed on the surface of the nanomagnetic support. The catalytic activity of CuFe2O4@SiO2-OSO3H was evaluated in the synthesis of 1,8dioxooctahydroxanthenes under solventfree conditions. The reactions using this nanomagnetic acidic catalyst could be carried out in lower than 12 min with excellent yields. Also, the catalyst was easily isolated from the reaction mixture by an external magnet and used at least four times without significant loss of activity.