Hydroamination of ethylene by aniline: catalysis in water

Abstract

The platinum-catalyzed and halide-promoted hydroamination of ethylene with aniline is reported for the first time in the presence of simple sodium halides in water. Compounds K₂PtX₄ (X = Cl or Br), PtX₂ or PtX₄ (0.3% mol) in the presence of an aqueous solution of excess NaX and aniline under ethylene pressure (25 bar) affords N-ethylaniline with 60–85 turnovers after 10 h at 150 °C. The best result (TON = 85) was obtained in the presence of excess NaBr, whereas a slightly lower activity was observed with NaCl (60 cycles) and practically no activity with NaF or NaI (2–4 cycles). The reaction also produces N,N-diethylaniline (up to 1 cycle) and 2-methylquinoline (up to 8 cycles) as by-products. The influence of added H⁺ and different oxidizing agents was also examined.