Magnetic nanoparticles tris(hydrogensulfato) boron as an efficient heterogeneous acid catalyst for the synthesis of α,ά-benzylidene bis(4-hydroxycoumarin) derivatives under solvent-free condition

Abstract

Nano-ferrite supported tris(hydrogensulfato) boron [Fe3O4@B(HSO4)3] was prepared by entrapping Fe3O4 magnetic nanoparticles as the core and tris(hydrogensulfato) boron B(HSO4)3 as the outer shell. This effective and magnetically recoverable catalyst was employed for the synthesis of α,ά-benzylidene bis(4-hydroxycoumarin) derivatives through the reaction of an aromatic aldehyde and 4-hydroxycoumarin under solvent-free conditions. This acid catalyst was characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis and differential scanning calorimetry, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller analysis, Barret–Joyner–Halenda analysis, vibrating sample magnetometer and titration.