Ionic Liquid Attached to Colloidal Silica ‎Nanoparticles as Catalyst for the ‎Synthesis of Pyrimidines

Bis (1(3-trimethoxysilylpropyl)-3-methyl-imidazolium) copper tetrachloride tethered to colloidal silica nanoparticles have been used as an efficient catalyst for the preparation of 2,4-diamino-6-arylpyrimidine-5-carbonitrile derivatives by the one-pot reaction of aromatic aldehydes, malononitrile, and guanidine hydrochloride under conventional heating, microwave and ultrasound irradiations. The catalyst was characterized by 1H NMR spectroscopy, dynamic light scattering (DLS), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA). The remarkable advantages of this methodology are easy work-up, short reaction times, high to excellent product yields, operational simplicity, low catalyst loading and use of ultrasonic irradiation as a valuable and powerful technology.