Developing effective catalyst system for reductive carbonylation of nitrobenzene based on the diversity of ionic liquids

Based on the diversity of ionic liquids, i.e. tunable structure and physicochemical properties, a series of functional ionic liquids and palladium complexes were investigated, and a highly effective catalyst system, Pd(phen)Cl2-BAcImPF6 ionic liquid (phen = 1,10-phenanthroline; BAcIm = 1-butyl-3-acetic acid-imidazolium), was developed for the reductive carbonylation of nitrobenzene to give the corresponding carbamate with higher than 90% of conversion and selectivity at 150 °C and 6 MPa carbon monoxide. The high catalytic performance is attributed to the acidic function of the BAcImPF6 ionic liquid and the interaction between Pd(phen)Cl2 and the ionic liquid to form the catalytically active palladium complex Pd(phen)2(PF6)2.

Graphical abstractThe reductive carbonylation of nitrobenzene could be effectively proceeded in the presence of palladium complex and acid-functionalized ionic liquids. Figure optionsDownload full-size imageDownload as PowerPoint slide