Preparation, characterization, and first catalytic application of a novel phosphotungstic acid-containing ionic liquid immobilized on CuFe2O4@SiO2 magnetic nanoparticles in the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones

Abstract

A novel heterogeneous acidic ionic liquid based on functionalized imidazolium salt of phosphotungstic acid (H₃PW₁₂O₄₀, denoted as PW), immobilized on CuFe₂O₄@SiO₂ magnetic nanoparticles, denoted as CuFe₂O₄@SiO₂@C₃-Imid-C₄SO₃-PW, was prepared and characterized using FT-IR, SEM, EDX, and VSM techniques. High activity of the prepared material as a novel catalyst was evaluated in one-pot synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones by reaction of phthalhydrazide with an aromatic aldehyde and malononitrile under solvent-free conditions. The process gave high yields of the products over short reaction time. The catalyst was efficiently recovered by magnetic decantation and used repeatedly without significant loss of its activity.