Highly selective hydrogenation of aromatic chloronitro compounds to aromatic chloroamines with ionic-liquid-like copolymer stabilized platinum nanocatalysts in ionic liquids

Platinum nanoparticles (PtNPs stabilized by an ionic-liq.-like-copolymer (IP) immobilized in various ionic liqs. (ILs)) effectively catalyze the selective hydrogenation of arom. chloronitro compds. to arom. chloroamines, a reaction of considerable com. significance. The prepn. of 2,4-dichloro-3-aminophenol (DAP) has been primarily studied due to its important industrial applications. DAP is usually prepd. from 2,4-dichloro-3-nitrophenol (DNP) by redn. with hydrogen using Ni- or Pt-based catalysts. Compared to reactions in mol. (org.) solvents, the ILs system provides superior selectivity with functionalized ILs contg. an alc. group demonstrating the best recyclability, and ultimately achieving a turnover no. of 2025 which is 750 fold higher than Raney nickel catalyst. A universal catalyst-ionic liq. system for the conversion of arom. chloronitro compds. to arom. chloroamines was also established. TEM, XPS, IR spectroscopy were used to characterize the morphol. of the nanocatalysts allowing their structure to be correlated to their activity.