Ethers fluonnation with cobalt

Fluonnation of aliphatic ethers at gentle conditions with cobalt trifluoride or potassium tetrafluorocobaltate do not give perfluorinated products and cause only negligible cleavage of the ether bond. Complex mixtures are formed from ethyl methyl ether and from diethyl ether [9] (equations 16 and 17)... 

Cyclic ethers having perfluorinated side chains or perfluorinated rings attached in the a-position with respect to oxygen are remarkably stable toward cobalt trifluoride and can be successfully fluonnated to perfluoro ethers at 440 °C without being cleaved to a considerable extent at the oxygen [16, 77]. Selected examples are shown in Table 4. 

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