Selective one-pot synthesis of aminopolyhalobenzonitriles from polyhalobenzotrichlorides in anhydrous ammonia

Abstract

Polyhalogenated benzotrichlorides (pentafluoro-, chlorotetrafluoro-, chlorotrifluoro-, and tetrafluorobenzotrichlorides) undergo one-pot ammonolysis+aminodefluorination by the action of anhydrous ammonia to form mono- and diamino derivatives of polyhalobenzonitriles. For the substrates comprising halogen at the para-position, the ammonolysis of the CCl3 group and the first aminodefluorination occur simultaneously in the temperature range from −33 to 5°C. The temperature of introducing the second NH2 group is higher by 60–100°C, whereby conditions were found for the selective synthesis of mono- and diaminopolyhalobenzonitriles. The use of anhydrous ammonia as a reagent and a solvent minimizes side reactions and simplifies an isolation of the high purity products.