Tin oxide nanoparticles (NP-SnO2): preparation, characterization and their catalytic application in the Knoevenagel condensation

Tin oxide (SnO2) nanoparticles were synthesized by modified thermal decomposition process. Taguchi analysis was used and three important synthetic factors, molar concentration ratio of [NaNO3]/[SnCl4], temperature and time of calcinations, which affect the size of SnO2 particles, were studied. The optimal conditions were determined using Taguchi robust design method and nano-sized SnO2 particles (similar to 2 nm) were obtained. Nanoparticles were characterized by X-ray diffraction, transmission electron microscopy and UV-visible spectroscopy techniques. The results show that tin oxide nanoparticles could be one of the most active and reusable catalysts in the Knoevenagel condensation. Different active methylene group compounds and diverse range of aldehydes were chosen to react in the presence of tin oxide nanoparticles at ambient temperature at solvent-free condition (SFC) with excellent isolated yields.