Synthesis, characterization and application of N,N,N',N'-tetramethylethylenediaminium-N-(silica-n-propyl)-N'-sulfonic acid chloride trifluoroacetate as a novel and effective catalyst for preparation of bis-coumarins

In this research, a novel material namely N,N,N',N'-tetramethylethylenediaminium-N-(silica-n-propyl)-N'-sulfonic acid chloride trifluoroacetate ([TEDSPSCT]) was synthesized, and its structure was characterized using Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDS), field emission scanning electron microscopy (FE-SEM), thermal gravimetric (TG), differential thermal gravimetric (DTG) and x-ray diffraction (XRD); most of the partcles were in nano-size, and a few of them were in micro-size. Afterward, [TEDSPSCT] was used as effective and recyclable catalyst for the preparation of bis-coumarins via the reaction of 4-hydroxycoumarin (2 equivalents) with arylaldehydes (1 equivalent) under solvent-free conditions; these compounds were obtained in high yields and short reaction times. Moreover, an attractive and logical mechanism based on dual-functionality of the catalyst has been described {this catalyst has both acidic group (SO3H) and weak basic group (trifluoroacetate)}.