An ester appending multifunctional ionic liquid for Pd(II) catalyzed Heck reaction
A basic, ester functionalized, imidazolium based ionic liquid (IL2), 3-Methyl-1-(ethoxycarbonylmethyl)imidazolium hydroxide was designed eyeing in situ generation and stabilization of palladium nanoparticles for palladium catalyzed Heck reaction of haloarenes and olefins. This phosphine-free Pd-IL catalyst demonstrated excellent activity and reusability at relatively low reaction temperature (80 °C) for a wide spectrum of haloarenes including chloroarenes. The relatively low reaction temperature could be attributed to in situ generation of uniform and spherical palladium nanoparticles (~ 5 nm).
Graphical abstractA basic ionic liquid was prepared and used for palladium catalyzed Heck reaction of aryl halides and olefins. The catalyst was applicable to aryl iodides, bromides and chlorides. The reactions were carried out at relatively low temperature (80 °C). This low reaction temperature could be attributed to in situ generation of Pd nanoparticles. The catalyst system could be reused up to five cycles without any substantial deactivation.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch Highlights► An ester functionalized basic ionic liquid for Pd catalyzed Heck reaction. ► The protocol is applicable to aryl iodides, bromides and chlorides as well. ► As there is in situ generation of palladium nanoparticles reaction occurs at 80 °C. ► The ionic liquid is stable and could be reused up to five cycles. ►It was also observed that the palladium nanoparticles regenerate after reaction.
Journal: Catalysis Communications - Volume 12, Issue 4, 15 December 2010, Pages 273–276