brønsted acidic phosphonium based ionic liquid functionalized sba-15 [ho3s-phospil@sba-15]: green, recyclable, and efficient catalyst for the synthesis of pyrano[3,2-c]chromenone derivatives

the surface of sba-15 was modified by diphenylphosphine; then, it was treated with butane sultone and sulfuric acid to obtain brønsted acid ho3s-phosphonium based ionic liquid functionalized sba-15 with hso4- as a counteranion. it efficiently catalyzed synthesis of pyrano[3,2-c]chromenone derivatives through the reaction of 4-hydroxycoumarin and chalcones at 60 °c in water/ethanol. good yields, mild reaction conditions, and user-friendly procedure are advantages of this method. also, the catalyst could be easily separated and reused five times without significant reduction of activity.