Introduction of O-sulfonated poly(vinylpyrrolidonium) hydrogen sulfate as an efficient, and reusable solid acid catalyst for some solvent-free multicomponent reactions

In this work, O-sulfonated poly(vinylpyrrolidonium) hydrogen sulfate ([PVP-SO3H]HSO4) has been prepared as a powerful recyclable solid acid catalyst and characterized using a variety of techniques including elemental analysis, FT-IR, TGA, SEM, XRD, pH analysis and Hammett acidity function. After preparation and identification the mentioned solid acid with wide acidic functional group sites, is utilized as a highly efficient catalyst for the synthesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones, 1-(benzothiazolylamino)phenylmethyl-2-naphthols and 2H-indazolo[2,1-b] phthalazine-1,6,11(13H)-triones in the absence of solvent. These eco-friendly protocols offer some advantages such as green and cost-effective procedures with excellent yields, shorter reaction times, simpler work-up, recovery, and reusability of a metal-free solid acid heterogeneous catalyst.