A silica gel supported dual acidic ionic liquid: an efficient and recyclable heterogeneous catalyst for the one-pot synthesis of amidoalkyl naphthols

A supported dual acidic ionic liquid catalyst was prepared via anchoring 3-sulfobutyl-1-(3-propyltriethoxysilane) imidazolium hydrogen sulfate onto silica gel by covalent bonds. The novel immobilized acidic ionic liquid effectively catalyzed the one-pot synthesis of amidoalkyl naphthols by the multicomponent condensation of aldehydes with 2-naphthol and amides under solvent-free conditions. Moreover, the catalyst could be recycled six-times without a significant loss of catalytic activity.