Covalently anchored 2-amino ethyl-3-propyl imidazolium bromideon SBA-15 as a green, efficient and reusable Brønsted basic ionic liquid nanocatalyst for one-pot solvent-free synthesis of benzopyranopyrimidines under ultrasonic irradiation

Abstract

In the present study highly ordered mesoporous SBA-15 having Brønsted basic ionic liquid pore channels was synthesized via surfactant-templated sol-gel methodology and post modification process. For this gold, Well-ordered mesoporous chloro-functionalized SBA-15 ,SBA-Cl, was first synthesized by the direct incorporation of chloropropyl groups through cocondensation of TEOS and CPTMS precursors in the presence of Pluronic P123 triblock copolymer as a supramolecular template to direct the organization of polymerizing silica. Afterwards, highly ordered 2-amino ethyl-3-propyl imidazolium bromide functionalized mesoporous SBA-15, SBA-Im-NH2, with high surface area was synthesized by nucleophilic substitution reaction of SBA-Cl with imidazole and then quaternization with 2-bromo ethylamine hydrobromide. The target organic-inorganic nanocomposite was characterized by FT-IR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray Diffraction (XRD) thermogravimetric analysis (TGA), Elemental analysis (CHN) and Brunauer-Emmett-Teller (BET). The SBA-Im-NH2 nanocomposite was successfully used as efficient Brønsted basic ionic liquid nanocomposite for preparation of benzopyranopyrimidine derivatives by the one-pot pseudo fourcomponents reaction of salicylaldehydes, malononitrile and secondary amines under ultrasonic and solvent free conditions at room temperature. This method has the advantages of high yields, a cleaner reaction, simple methodology, short reaction times, easy work-up, and greener conditions. In addition to the facility of this methodology, it also enhances product purity and promises economic as well as environmental benefits.