Perfluoro ethers fluonnation

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. 

The basicities of amines, ethers, and carbonyl compounds are invariably decreased by fluonnation. 2,2,2-Tnfluoroethylamine (p f = 3.3 [61]) and C 5NH2 = -0.36 [62]) are about 10 times less basic than CH3CH2NH2 and CgH5NH2, respectively, and (CF3)2CHNH2 (p j, = 1 22 [71]) is over 10 times less basic than 1-C3H2NH2. The relative gas-phase acidities in Table 15 illustrate the large effect of fluonnation. Perfluoro-rerf-amines (R )3N and ethers R Rf have no basic character m solution [, 74], and CF3COCF3 is not protonated by superacids [72]. 

The high thermal and chemical stability of fluorocarbons, combined with their very weak intermolecular interactions, makes them ideal stationary phases for the separation of a wide variety of organic compounds, including both hydrocarbons and fluorine-containing molecules Fluonnated stationary phases include per-fluoroalkanes, fluorocarbon surfactants, poly(chlorotrifluoroethylene), polyfper-fluoroalkyl) ethers, and other functionalized perfluoro compounds The applications of fluonnated compounds as stationary phases in gas-liquid chroma... 

During electrochemical fluorination retention of important functional groups or atoms in molecules is essential. Acyl fluorides and chlorides, but not carboxylic acids and anhydrides (which decarboxylate), survive perfluorination to the perfluorinated acid fluorides, albeit with some cyclization in longer chain (>C4) species [73]. Electrochemical fluonnation of acetyl fluoride produces perfluoro-acetyl fluoride in 36-45% yields [85]. Electrochemical fluonnation of octanoyl chloride results in perfluonnated cyclic ethers as well as perfluorinated octanoyl fluonde. Cyclization decreases as initial substrate concentration increases and has been linked to hydrogen-bonded onium polycations [73], Cyclization is a common phenomenon involving longer (>C4) and branched chains. a-AIkyl-substituted carboxylic acid chlorides, fluorides, and methyl esters produce both the perfluorinated cyclic five- and six-membered ring ethers as well as the perfluorinated acid... 

The reactions of some fluonnated ethers may result in the elimination of alkyl fluorides In the case of 2-methoxyperfluoro-2-butene, treatment with antimony pentafluonde gives perfluoro-3-buten-2-one and methylfluoride [7071 By reacting 2-chloro-l,l,2-trifluorodiethyl ether with boron trifluonde etherate or with aluminum chloride, chlorofluoroacetyl fluonde can be obtained with the elimination of ethyl fluonde [108] (equations 76 and 77)... 

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