Efficient Catalytic System for Chemoselective Hydrogenation of Halonitrobenzene to Haloaniline Using PtZn Intermetallic Compound

Nanoparticulate intermetallic PtZn acts as a highly efficient heterogeneous catalyst for chemoselective hydrogenation of halonitrobenzenes to haloanilines. Chloroanilines, bromoanilines, and iodoanilines, including all regioisomers, were obtained with excellent yields (typically >99%) under 1 atm H-2 at 40 degrees C. A gram-scale reaction afforded a turnover number (TON) of 8600. PtZn/SiO2 could be reused at least four times without significant loss of catalytic performance. PtZn/SiO2 afforded 7-fold higher TOF than Pt/SiO2. A combination of kinetic analysis, X-ray photoelectron spectroscopy (XPS) studies, and density functional theory (DFT) calculations revealed that electron-enriched Pt by Zn not only promotes nitro-hydrogenation but also effectively inhibits the carbon-halogen bond scission.