Amino acid ionic liquid-based titanomagnetite nanoparticles: An efficient and green nanocatalyst for the synthesis of 1,4-dihydropyrano[2,3-c]pyrazoles

摘要

The amino acid ionic liquid tetrabutylammonium asparaginate (TBAAsp) was immobilized on titanomagnetite (Fe3-xTixO4) nanoparticles in a facile one-pot process using an organosilane compound (TMSP) as spacer. The modified Fe3-xTixO4@TMSP@TBAAsp magnetic nanoparticles were characterized using Fourier transform spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry and thermogravimetric analysis. The resulting analytical data clearly verified the successful immobilization of the ionic liquid on the magnetic substrate. The magnetic ionic liquid-based nanoparticles exhibited high catalytic activity in the synthesis of 1,4-dihydropyrano[2,3-c]pyrazole derivatives via a one-pot three-component reaction under mild reaction conditions. The catalyst was easily recycled and reused for at least six runs without any considerable loss of activity.