Chemical Recycling of Hydrofluorocarbons by Transfer Fluorination

Fluorochemicals improve our quality of life, there is however increasing concern over how they are made and their negative impacts on health and the environment. Here we report an approach to the recycling of fluorochemicals. Treatment of hydrofluorocarbons with a potassium base (KHMDS, KOtBu) results in rapid defluorination to produce anhydrous potassium fluoride. The potassium fluoride can then be used to prepare a wide range of fluorinated organic and inorganic molecules including sulfonyl fluorides, aryl fluoride, alkyl fluorides, aryl fluorides and a range of p-block fluorides, in an overall one-pot transfer fluorination process. The scope of fluorochemicals that can be recycled by transfer fluorination includes industrially relevant refrigerants (HFCs), hydrofluoroolefins (HFOs), fluoroethers – including anaesthetics and battery additives, perfluorooctanoic acid (PFOA), and poly(vinylidene difluoride) (PVDF). Aspects of the mechanism of the transfer fluorination have been investigated through DFT calculations and approaches to scale up using batch (50 g) and flow (1.5 g h-1) chemistry presented.