Swarts fluorination

Swarts fluorination is a process whereby the chlorine atoms in a compound – generally an organic compound, but experiments have been performed using silanes – are replaced with fluorine, by treatment with antimony trifluoride in the presence of chlorine or of antimony pentachloride.

Heating the mixture of the metal fluoride and the haloalkane (chlorine and bromine are replaced readily) yields the desired fluoroalkane.

In some particularly reactive cases, heating is unnecessary; shaking or stirring the reaction mixture is sufficient.

The process was initially described by Frédéric Jean Edmond Swarts in 1892.

[1] The active species is antimony trifluorodichloride 2, which is produced in situ from the reaction between antimony trifluoride 1 and chlorine; this compound can also be produced in bulk, according to a patent of John Weaver.