Introduction of a new ionic liquid solid acid based on clay as an efficient, recyclable and thermally stable catalyst for organic transformations

Abstract

Ammonium hydrogen sulfate based ionic liquid immobilized on Na⁺–montmorillonite (AHS@MMT) was prepared via anchoring ammonium hydrogen sulfate propyltriethoxysilane onto sodium montmorillonite by covalent bonds. The synthesized catalyst was full characterized by FT-IR, SEM, TGA and XRD techniques and Hammett acidity test and the catalytic activity of this novel catalyst was evaluated for the synthesis of coumarin and xanthene derivatives. High yields of the products and simple workup and separation of them, easy separation and recovery of catalyst, solvent free conditions and use of an inexpensive catalyst are some of the advantages of our procedure. Also this catalyst can be reused several times without loss of its catalytic activity.