Fowler process

A way to moderate the reaction was required, and the method developed was to react the hydrocarbon with cobalt(III) fluoride, rather than fluorine itself.

For cyclic perfluorocarbon, the aromatic hydrocarbon is the preferred choice, so for example, toluene is the feedstock for perfluoromethylcyclohexane, rather than methylcyclohexane, as less fluorine is required.

Although these are considerably more expensive, they require less fluorine and more importantly, they generally give higher yields, as the carbocation rearrangements are much less likely.

In the UK, Imperial Chemical Industries Limited (later ICI) was also developing cobalt(III) fluoride technology during the war, prompted by the work in the US.

[6] The process was later commercialized under the tradename Flutec by the Imperial Smelting Company (later ISC Chemicals) at Avonmouth near Bristol.