Development of palladium catalysts immobilized on supported phosphonium ionic liquid phases

Abstract

The application of heterogeneous palladium catalysts supported on phosphonium ion modified silica was investigated in aminocarbonylation reactions of aryl iodides. In contrast to catalysts immobilized on supports decorated with imidazolium ions, the application of phosphonium type supported ionic liquid phases made it possible to carry out double carbonylation with good selectivity in apolar toluene which led to a considerable decrease in the amount of leached palladium. An even better stabilization of the palladium catalyst could be achieved by introducing dicationic organic moieties incorporating both imidazolium and phosphonium ions on the surface of the support. At the same time, the former catalyst, obtained from the supported phosphonium ionic liquid phase was found to be superior in monocarbonylations. The amide products were obtained in good yields by the proper choice of the reaction conditions, such as reaction temperature and pressure and that of the base.