Diethanolamine and N,N-diethylethanolamine ionic liquids as precatalyst-precursors and reaction media in green Heck reaction protocol

It was found that Heck reaction with PdCl2 in diethanolamine and N,N-diethylethanolamine ionic liquids (ILs) is more efficient than analogous reactions performed in classical organic solvents. The used ILs facilitate solubility of the Pd(II) precatalysts, increase catalyst stability during the reaction, and function as reaction media, bases, precatalyst-precursors, good coordinating ligands, and mobile support for active Pd species. Thus, Heck reaction occurs without additional solvents, ligands and bases, that makes experimental procedure much simpler. Our DFT investigation provides mechanistic insight into the formation of the trans-[PdCl2(DEA)2] complex that acts as a precatalyst.

Graphical abstractThe reaction of PdCl2 with diethanolamine and N,N-diethylethanolamine ionic liquids 1–4 provides the effective and recyclable ionic liquid–palladium catalytic systems for green Heck reaction.Figure optionsDownload full-size imageDownload high-quality image (100 K)Download as PowerPoint slide