Molybdic Acid-Functionalized Nano-Fe3O4@TiO2 as a Novel and Magnetically Separable Catalyst for the Synthesis of Coumarin-Containing Sulfonamide Derivatives

Abstract

Supported molybdic acid on nano-Fe₃O₄@TiO₂ (Fe₃O₄@TiO₂@(CH₂)₃OMoO₃H) has been successfully prepared, characterized and applied as a catalyst for the synthesis of sulfonamide containing coumarin moieties. The prepared Fe₃O₄ nanoparticles by coprecipitation of Fe²⁺ and Fe³⁺ ions were treated with tetraethyl orthotitanate to obtain Fe₃O₄@TiO₂. By anchoring 3-chloropropyltriethoxysilan on Fe₃O₄@TiO₂ followed by reacting with molybdic acid, the desired catalyst was produced. The synthesized catalyst was characterized using XRD, SEM, EDS, FT-IR and VSM analysis. Fe₃O₄@TiO₂@(CH₂)₃OMoO₃H was used as a catalyst for the synthesis of sulfonamide containing coumarin moieties via a three-component reaction of aryl aldehydes, para-toluenesulfonamide and 4-hydroxycoumarin or 5,7-dihydroxy-4-methylcoumarin. The catalyst recovery test showed the catalyst is highly reusable without losing its activity.