-> 1-fluoro-4-nitrobenzene
:1,2-dichloronitrobenzene -> 1-chloro-2-fluoro-5-nitrobenzene
:1,4-dichloronitrobenzene -> 1-chloro-4-fluoro-3-nitrobenzene
:1-chloro-2,4-dinitrobenzene -> 1-fluoro-2,4-dinitrobenzene
:5-chloro-2-nitrobenzotrifluoride -> 5-fluoro-2-nitrobenzotrifluoride
:1,3-dichloro-4-nitrobenzene -> 1,3-difluoro-4-nitrobenzene
:2,6-dichlorobenzonitrile -> 2,6-difluorobenzonitrile

The nitro groups