Chemoselective reduction of aromatic nitro and azo compounds in ionic liquids using zinc and ammonium salts

摘要

Nitroarenes were chemoselectively reduced to the corresponding amines using zinc and aqueous ammonium salts in ionic liquids as a safe and recyclable reaction medium. Our results specify the effect of ammonium salts in the process; the combination of Zn/NH_4Cl in [bmim][PF_6] or Zn/HCO_2NH_4 in [bmim][BF_4] were the suitable conditions for the reduction of nitroarenes. Azobenzenes were also smoothly reduced to hydrazobenzenes with Zn/HCO_2NH_4 (aq.) in recyclable [bmim][BF_4] without any over reduction to the corresponding anilines.