The First Pyrazolium-Based Ionic Liquid Containing Phosphotungstic Acid Immobilized on CuFe۲O۴@SiO۲: A Recyclable Organic-Inorganic Nanohybrid Catalyst for the Synthesis of Polyhydroquinolines

A new magnetically separable organic-inorganic nanohybrid catalyst denoted as CuFe۲O۴@SiO۲@C۳-Pyrazole-C۴SO۳-H۲PW was successfully prepared by grafting of a functionalized ionic liquid containing a pyrazolium cation with a phosphotungstic counter-anion H۲PW۱۲O۴۰¯ (H۲PW) on silica-coated copper ferrite magnetic nanoparticles (CuFe۲O۴@SiO۲). The prepared catalyst was fully characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis, inductively coupled plasma optical emission spectrometry, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. The catalytic activity of CuFe۲O۴@SiO۲@C۳-Pyrazole-C۴SO۳-H۲PW as a novel heterogeneous catalyst was probed in the synthesis of polyhydroquinolines by one-pot condensation of dimedone, an aromatic aldehyde, ammonium acetate, and ethyl acetoacetate. The results demonstrated a significant catalytic performance of the catalyst for this transformation under solvent-free conditions, giving high yields of the products over short reaction time. Also, the magnetic nanocatalyst could be easily recovered from the reaction mixture and reused many times with no significant loss of its catalytic activity.

کلیدواژه ها:

CCuFe۲O۴@SiO۲@C۳-Pyrazole-C۴SO۳-H۲PW ، Ionic liquid ، Magnetic nanoparticles ، polyhydroquinolines