SYNTHESIS OF 3,4-DIFLUOROBENZONITRILE AND MONOFLUOROBENZONITRILES BY MEANS OF HALOGEN-EXCHANGE FLUORINATION

Article abstract of DOI:10.1016/S0022-1139(00)80348-6

3,4-Difluorobenzonitrile has been prepared by a halogen-exchange reaction between 3,4-dichlorobenzonitrile and spraydried potassium fluoride in the presence of tetraphenylphosphonium bromide in refluxing 1,3-dimethylimidazolidine-2-one.In the fluorination reaction, 4-chloro-3-fluorobenzonitrile seems to be a key intermediate. 3,4-Difluorobenzonitrile, 2-, 3-, and 4-fluorobenzonitriles have also been produced from the corresponding chlorobenzonitrile derivatives by halogen-exchange at 290 deg C, in DMI in a pressure reactor.