Double Brønsted Acidic Media Immobilized on Carbonized Sugarcane Bagasse (CSCB) as a New and Efficient Solid Acid Catalyst for the Synthesis of Coumarins, Dicoumarols and Xanthenes

Abstract This work is the first report on use of carbonized sugarcane bagasse as a carbon bed for a double Brønsted acidic ionic liquid for the synthesis of a new functionalized solid acid catalyst. Immobilization of hydrogen sulfate was performed from the reaction of 3‐amino propyltriethoxysilane with carbonized bagasse and sulfonation of amine groups using sulfuric acid. Thus, ammonium hydrogen sulfate supported sugarcane bagasse (AHS@CSCB) was prepared. The catalyst (AHS@CSCB) was fully characterized by FT‐IR, XRD, TGA, FE‐SEM, elemental‐mapping and EDX techniques. Also, the surface acidity of catalyst was studied by Hammett function. Catalytic properties of the synthesized catalyst were examined in the synthesis of coumarins, dicoumarols and dibenzoxanthenes. All of the products were obtained with high yields in short reaction times and solvent‐free conditions and characterized with 1 H and 13 CNMR or previously reported products were examined by comparison with reported melting points. Some of the advantages of our method are simple preparation of catalyst and safe handling, very low cost of support and its abundance, high products yield, catalyst recyclability, solvent‐free and easy workup.