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

Abstract

<em>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</em>. <em>Good yields, mild reaction conditions, and user-friendly procedure are advantages of this method.</em> <em>Also</em>, <em>the catalyst could be easily separated and reused five times without significant reduction of activity.</em>