Synthesis of Fe3O4@C-SO3H nanoparticles as magnetically acid catalyst for the preparation of dihydropirimidinone

Recently, the carbon based solid acid catalysts with high acidity and thermal stability have received wide attention [1]. Although the sulfonated carbon catalyst is active its speration from the reaction mixture is still achallenge during the practical application. The catalyst is generally recovered by the filtration or centrifugation methods which are dependent on special apparatus and time consuming. More recently, a magnetic sulfonatedmesoporous silica catalyst was reported for thehydrolysis of biomass, indicating that the magnetismseparation could be a feasible way to separate thecatalytic material from the reaction residues [2, 3]. Herein we report a method for the synthsis ofnew Magnetic Nano-catalyst with core-shell structure (Fe3O4@C-SO3H).Fe3O4@C-SO3H has been synthesized through the hydrothermal carbonization of glucose with magnetic cores and sulfonation of carbonaceous intermediate with PTSA (Scheme). Subsequently, the structure and morphologyof the preparednanocatalyst were studied with some differentspectroscopic, microscopic andthermogravimetric techniques such as FT-IR, XRD, FESEM and CHNS-Analysis.The magnetic Fe3O4 core makes the catalysts easily separated from reaction mixtures by using the externally applied magnetic field The application of this new nanocatalyst allows the synthesis of a Dihydopirimidinone through the reaction of aldehydes with urea and β-ketoesters undersolvent-free conditions. This synthetic pathway is a green protocol offering significant advantages, suchas easy preparation of the catalyst, mild reaction conditions and minimization of chemicalwaste..