4-Fluoronitrobenzene

4-Fluoronitrobenzene is an organic compound with the formula FC6H4NO2. It is one of three isomeric fluoronitrobenzenes. A yellow oil, it is prepared from 4-nitrochlorobenzene using the Halex process:
 * O2NC6H4Cl + KF  ->  O2NC6H4F  +  KCl

4-Fluoronitrobenzene can be hydrogenated to give 4-fluoroaniline, which is a precursor to the fungicide fluoroimide.

Owing to the presence of the electron withdrawing nitro group, the fluoride is a good leaving group in fluoronitrobenzenes. Thus reaction with phenoxide gives the mononitrodiphenylether.