Introduction of versatile and recyclable network poly (ionic liquid)s as an efficient solvent with desired properties for application in C[sbnd]C cross-coupling reactions

Abstract

Synthesis of high viscosity, ecofriendly, and low melting point poly(ionic liquid)s (LMP-PIL) with network structure has been introduced by the reaction of 1,1′,1′′‑(1,3,5‑triazine‑2,4,6‑triyl) tris(3‑methyl‑1H‑imidazol‑3‑ium) iodide ionic liquid (TAIm[I] IL) monomer with disodium salts of various open-chain carboxylic acids as well as sulfonic acids via a polycondensation on counter ions (PC-CI). Change in alkyl group length in carboxylate, as well as sulfonate, provide a broad spectrum of properties in terms of viscosity, density, and solubility for the resulting PILs. The physical properties of the PILs including, viscosity, melting point, boiling point, density,M¯n, and polydispersity (Ð), were determined in this study. Also, thermal behavior of the PILs were studied in comparison with the corresponding monomers. The ecofriendly PILs served as an efficient solvent and ligand for the Cu-catalyzed Heck and Sonogashira CC coupling reactions. High to excellent yields were obtained for various coupling products under mild conditions at melting points of the PILs. Also, the coupling products could be obtained with direct scalability. The prepared PILs could be recycled several times from the homogenous reaction mixture with preservation of the intrinsic properties. Also, a detailed study was conducted on the mechanism of the coupling reactions.