Perfluoroalkanoic acid fluoride

Electrochemical fluorination of an alkanoic acid yields a perfluoroalkanoic acid fluoride [43-47] ... 

Electi ochemical fluorination of carboxylic acids produces perfluoroalkanoic acid fluorides in a low yield (about 10-20%) [31] and water as a by-product. Water forms explosive oxygen difluoride and causes oxidative degradation of the carboxylic acid. For acids with six or more carbon atoms, cyclic perfluoroethers are among the by-products formed. The anhydrides of carboxylic acids give per-fluorocarboxylic acid fluorides in a higher yield than the parent carboxylic acids. The electrochemical fluorination of carboxylic acids or their anhydrides is now obsolete. 

The carboxylic acid fluorides are soluble in HF, and the solutions of alkanoic acid fluorides with more than four carbon atoms are conductive. The yield of the perfluoroalkanoic acid fluoride decreases with increasing chain length of the carboxylic acid fluoride fluorinated, from as much as about 80% for acetyl fluoride to 10% for perfluorooctanoyl fluoride [34]. The yield is lower when an acyl chloride is fluorinated instead of an acyl fluoride, but aeyl chlorides are more readily available than acyl fluorides [48]. 

Esters 8 of perfluoroalkanoic acids and perfluorinated or highly fluorinated alcohols react with the sulfur tetrafluoride/hydrogen fluoride mixture without cleavage to give high yields of perfluorinated or highly fluorinated ethers 9.164-165... 

Perfluoroalkylcopper reagents are the most studied perfluoroalkyl organometallic reagents due to their unique combination of thermal stability and chemical reactivity. They are readily prepared by copper metal insertion reactions with perfluoroalkyl halides in a coordinating solvent (e.g., formation of decarboxylation reactions of perfluoroalkanoic acid salts and copper(I) halide (e.g., formation of 2 ), or metathesis reactions (e.g., formation of 4 via 3 ). (Trifluoro-methyl)copper (4) has also been recently accessed by decomposition of methyl 2,2-difluoro-2-(fluorosulfonyl)acetate (5) or methyl perfluoro [2-(fluorosulfonyl)ethoxy]acetate (6) in the presence of copper(I) iodide and by reaction of trimethyl(trifluoromethyl)silane (7) with fluoride and copper(I) iodide. ... 

A range of normal functional-group chemistry may be carried out with perfluoroalkanoic acids, little modified by the perfluoroalkyl group [2, 25, 26]. Acid chlorides are readily obtained with thionyl chloride or phosphoms chlorides and may be converted to the fluorides using potassium fluoride or, where a volatile product is obtained, by exchange with benzoyl fluoride (see Chapter 3, Section IIB) anhydrides are produced by reaction of the acid with phosphorus pentoxide [27]. To illustrate some of the chemistry of perfluoroalkanoic acids, a selection of reactions is contained in Table 8.3. 

In order to compare the relative nucleophilic reactivity of perfluorophenyl perflu-oroalkanoates and sulfonates, both polyfluorophenyl perfluoroalkanoates (9) and bis(perfluorophenyl) diesters (10) were synthesized from the reaction of the corresponding acid fluorides with sodium polyfluorophenoxide in monoglyme118. 

Straight-chain perfluoroalkanoic or perfluoroalkanesulphonic acids fluorides derived by electrofluorination can be subjected to hydrolysis, esterification, amidation and other modifying, as illustrated with the following reactions [124, 126] ... 

Perfluoroalkanecarbonyl fluorides produced by the electrochemical fluori-nation process are hydrolyzed to produce a perfluoroalkanoic acid or its salt ... 

Oxidation of perfluoroalkyl iodides with fuming sulfuric acid in the presence of P2O5 and rectification of the reaction mixture gives the fluoride C F2 + iCOF, which is hydrolyzed with water to produce the acid C F2 + tCOOH. Perfluoroalkanoic acids have also been obtained by carbonation of fluo-... 

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See also in sourсe #XX -- [ ]

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