Kaolin sulfonic acid nanoparticles: An efficient and reusable heterogeneous catalyst for the synthesis of highly substituted pyrazoles via a green protocol

Abstract

Kaolin sulfonic acid nanoparticles (Nano-kaolin-SO3H) as a recoverable solid catalyst was prepared by reaction of kaolin nanoparticles with chlorosulfonic acid. After characterization of kaolin-SO3H nanoparticles by ATR, XRD, TEM, XRF, FESEM, EDS, EDS mapping, BET and TGA techniques, this solid acid used to synthesize highly substituted pyrazoles via condensation of hydrazine derivatives with various β-diketones. The reaction was proceeded in a short time, simple work-up, easy purification technique, high yields, solvent free conditions and above all environmentally benign.