S(=O)(=O)(O)O.[N+]([O-])(O)=O.FC1C=CC=CC=1.[Cl:17]Cl.[N+](C1C=CC=CC=1F)([O-])=O.[Cl:29][C:30]1[C:31]([F:39])=[C:32]([N+]([O-])=O)[CH:33]=[CH:34][CH:35]=1>>[CH:33]1[C:34]([Cl:17])=[CH:35][C:30]([Cl:29])=[C:31]([F:39])[CH:32]=1Process for the preparation of 2,4-dichlorofluorobenzene in high yield and purity without intermediate separation of the isomers formed,(1) by nitrating 1 mol of fluorobenzene to give nitrofluorobenzene using a mixture comprising 35 to 65 parts by weight of 50 to 90% strength sulfuric acid and 35 to 65 parts by weight of a nitrating acid comprising 35 to 55 parts by weight of 95 to 98% strength sulfuric acid and 45 to 65 parts by weight of 96 to 98% strength nitric acid, with the proviso that 0.8 to 2.0 equivalents of the nitrating agent NO2+ are used per mol of fluorobenzene, at 20° to 90° C., (2) allowing 25 g to 150 g of chlorine, in the presence of a ring chlorinating catalyst, to act on each 100 g of the crude nitrofluorobenzene mixture obtained, at 20° to 100° C., and (3) allowing about 18 g to about 203 g of chlorine or equivalent amounts of a chlorine releasing agent to act on each 100 g of the crude chlorofluoronitrobenzene mixture obtained, after removal of the ring chlorinating catalyst, at 110° to 220° C., and isolating the 2,4-dichlorofluorobenzene.
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