Triethylammonium chloride modified graphene oxide as a novel and the highly efficient catalyst for the production of bis-coumarins

This research reports the synthesis of bis-coumarins using graphene oxide functionalized by triethylammonium chloride (GO@TETA-CAC-Et3N+.Cl−) as a sustainable and efficient catalyst. The synthesis was achieved through the reaction of 4-hydroxycoumarin and benzaldehydes via a multicomponent reaction under no-solvent conditions. Firstly, graphene oxide was produced by a modified Hummers procedure and treated with triethylenetetramine. The product was subsequently modified by chloroacetyl chloride and then triethylamine to achieve the catalyst (GO@TETACAC- Et3N+.Cl−). The catalyst structure was then confirmed by FESEM, thermogravimetric analysis (TGA), XRD, EDS, X-ray elemental mapping technique, and FTIR. The catalyst offered some advantages over conventional ones, including environmental compatibility, stability, costeffectiveness, and nonmetal components, as well as recoverability and safe handling. The applied procedure is superior to other methods due to its easy workup, sustainability, solvent-free medium, high yield, short reaction time, and no byproduct. Research Highlights: • The synthesis of bis-coumarins using GO@TETA-CAC-Et3N+.Cl- as a sustainable and efficient catalyst was reported. • The synthesis of bis-coumarins was carried out under solvent-free conditions. • The catalyst offered some advantages over conventional ones including environmental compatibility, stability, cost-effectiveness, and nonmetal components, as well as recoverability, and safe handling. • This methodology is superior over other methods due to its easy work up, high yield, short reaction time, and no byproduct.