Ionic Liquid Supported on Magnetic Graphene Oxide as a Highly Efficient and Stable Catalyst for the Synthesis of Triazolopyrimidines

Abstract

A novel sulfonic acid functionalized ionic liquid was prepared by anchoring 1-(propyl-3-sulfonate) vinylimidazolium hydrogen sulfate ([(CH₂)₃SO₃HVIm]HSO₄) on Fe₃O₄@GO. The prepared heterogeneous catalyst was characterized by XRD, FT-IR, EDX, SEM, VSM and TGA techniques. The results show that [(CH₂)₃SO₃HVIm]HSO₄ was successfully deposited on the surface of Fe₃O₄@GO and the prepared ionic liquid catalyst exhibited good thermal stability. The activity of the prepared catalyst was investigated in the synthesis of triazolo[1,5-a]pyrimidine derivatives by a one-pot three-component reaction of active methylene compound (malononitrile or ethyl cyanoacetate), 3-amine-1H-1,2,4-triazole and aryl aldehydes under solvent-free conditions. This catalyst could be rapidly separated by an external magnet and recycled seven times without significant loss of catalytic activity.