In situ synthesis of SO(3)H supported Fe(3)O(4)@resorcinol–formaldehyde resin core/shell and its catalytic evaluation towards the synthesis of hexahydroquinoline derivatives in green conditions

A novel spherically shaped core@double-shell acidic nanocatalyst (Fe(3)O(4)@SiO(2)@RF–SO(3)H) [RF: resorcinol–formaldehyde resin] was prepared in situ and completely characterized using X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, energy dispersive X-ray spectroscopy, thermogravimetric analysis, transmission electron microscopy and field-emission scanning electron microscopy. The concentration of H(+) loaded on the Fe(3)O(4)@SiO(2)@RF was reported to be 1.3 mmol g(−1). The well-defined Fe(3)O(4)@SiO(2)@RF–SO(3)H core–shell heterostructures exhibited high stability, efficient recyclability (10 cycles), and promoted catalytic activity for one-pot condensation reaction between the aromatic aldehydes, dimedone, malononitrile, and ammonium acetate for the synthesis of hexahydroquinoline derivatives.