1-Chloro-3,4-difluoro-benzene, an intermediate in the production of certain quinolone drugs, is produced by converting a chlorofluoro-aniline into the corresponding diazonium fluoborate, and pyrolysing the latter to give the 1-chloro-3,4-difluorobenzene.
5-Chloro-2-fluorophenyldiazonium fluoborate is a new compound.