Halex process

In chemistry, the Halex process is used to convert aromatic chlorides to the corresponding aromatic fluorides. The process entails Halide exchange, hence the name.^[1] The reaction conditions call for hot (150-250 °C) solution of the aryl chloride in dimethylsulfoxide and anhydrous potassium fluoride. Potassium chloride is generated in the process. The reaction is mainly applied to nitro-substituted aryl chlorides.

The following reactions are practiced commercially in this manner:^[2]

1-chloro-2-nitrobenzene → 1-fluoro-2-nitrobenzene

1-chloro-4-nitrobenzene → 1-fluoro-4-nitrobenzene

1,2-dichloro-4-nitrobenzene → 1-chloro-2-fluoro-5-nitrobenzene

1,4-dichloro-2-nitrobenzene → 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

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