Catalytic application of zwitterionic palladium complexes in Mizoroki–Heck reactions using ionic liquid as solvent

•Three new ligand precursors with different dangling alkyl chain length were prepared.•Three new zwitterionic palladium complexes based on the new ligand precursors were synthesized.•The new palladium complexes were effectively applied as catalysts for Mizoroki–Heck reactions in ionic liquid.•TEM analysis revealed the formation of palladium nanoparticles in the catalytic reactions.

New ligand precursors with different pendent alky chain length were obtained in a single step by reacting appropriate 1-alkyl-2-methyl-1H-imidazoles with chloroacetone in THF at 80 °C overnight. Zwitterionic palladium complexes were prepared by reacting PdCl2 with these new imidazole derivatives in DMF with the presence of pyridine and Cs2CO3 as base at room temperature for 5 h. These new compounds were characterized by 1H and 13C{1H} NMR spectroscopy, elemental analysis, and electrospray ionization mass spectrometry. They were effectively applied as recyclable catalysts for mediating Mizoroki–Heck reactions in ionic liquids. Transmission emission microscopy revealed that palladium nanoparticles were formed during the catalytic process.

Graphical abstractBy reacting 1-alkyl-2-methyl-1H-imidazoles with chloroacetone, we developed new ligand precursors with different pendent alky chain length. Novel zwitterionic complexes were synthesized by reacting PdCl2 with these derivatives. The complexes formed effective recyclable catalyst systems for Mizoroki–Heck reactions in ILs. TEM revealed the formation of palladium nanoparticles during the catalytic process.Figure optionsDownload full-size imageDownload as PowerPoint slide