In chemistry, the Halex process is used to convert aromatic chlorides to the corresponding aromatic fluorides. The process entails ''Hal''ide ''ex''change, hence the name. The reaction conditions call for hot (150-250 °C) solution of the aryl chloride in

dimethylsulfoxide Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula ( CH3)2. This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and ...

and anhydrous

potassium fluoride Potassium fluoride is the chemical compound with the formula KF. After hydrogen fluoride, KF is the primary source of the fluoride ion for applications in manufacturing and in chemistry. It is an alkali halide and occurs naturally as the rare ...

. 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:{{Ullmann, first1=Günter , last1=Siegemund, first2=Werner, last2=Schwertfeger, first3=Andrew, last3=Feiring, first4=Bruce, last4=Smart, first5=Fred, last5=Behr, first6=Herward, last6=Vogel, first7=Blaine , last7=McKusick, title=Fluorine Compounds, Organic, year=2002, doi=10.1002/14356007.a11_349. :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

References

Fluoroarenes Phenyl compounds