Preparation and characterization of hexamethylenetetramine-functionalized magnetic nanoparticles and their application as novel catalyst for the synthesis of pyranopyrazole derivatives

A new magnetic catalyst was prepared through the reaction of silanol groups, on the surface of silica-coated Fe3O4 magnetic nanoparticles, with (3-chloropropyl)triethoxysilane followed by hexamethylenetetramine and chlorosulfonic acid. The obtained magnetic catalyst was characterized using thermogravimetric analysis, vibrating sample magnetometry, scanning electron microscopy and energy-dispersive X-ray analysis. Its catalytic activity was investigated in the synthesis of pyranopyrazole compounds, and the results were excellent regarding high yield of the products and short reaction time.