Self-Catalyzed Coupling between Brønsted-Acidic Imidazolium Salts and Epoxy-Based Materials: A Theoretical/Experimental Study
journal contributionposted on 12.11.2019, 23:29 by Magdalena Perchacz, Libor Matějka, Rafał Konefał, Leandro Seixas, Sebastien Livi, Jérôme Baudoux, Hynek Beneš, Ricardo K. Donato
Herein we present a comprehensive study on the role of Brønsted-acidic imidazolium ionic liquids (ILs) and imidazolium salts promoting the reaction between carboxyl and epoxide groups in a controlled manner at solvent-free and mild conditions. ILs were evaluated toward their ability to self-catalyze reactions between carboxyl groups and epoxy rings. Thus, an epoxy model reactant denoted phenyl glycidyl ether (PGE) was reacted with different ILs, and the reaction kinetics was followed by time-dependent FTIR spectroscopy. The resulting products were characterized by 1H NMR and MALDI-TOF, which also allowed a comprehensive investigation of the reaction mechanism by following the reaction intermediates formation. The detected intermediates were then evaluated by density functional theory (DFT) simulations to calculate their energy profiles, revealing the preferred mechanism pathways. These mono-, bi-, and tetra-functionalized ILs (with carboxyl groups) acted as all-in-one reaction systems for materials synthesis or modification, with the potential of producing a broad range of epoxy based materials via metal catalyst-free coupling reactions.