Octanoyl fluoride

A1 9 OCTALONE 2, 46, 80 A9(10,-Octdlone 2,45, 80 Octanal, 47, 96 Octanoyl fluoride, 46, 6 M-Octyl iodide, reaction with tnmethyl amine oxide to yield octanal, 47, 96... 

Electrochemical fluorination (ECF) is described in Section 6.4.7. for the manufacture of surface-active agents. Coproducts from the ECF of octylsulfonyl fluoride are linear perfluoro-carbons containing from three to eight carbon atoms, while octanoyl fluoride yields a mixture of perfluorocyclic ethers containing mainly perfluoro(2-butyltetrahydrofuran) and perfluoro(2-propylpyran). ECF is also used for the manufacture of specific perfluorocarbon fluids, notably perfluoro(tripropylamine) and perfluoro(tripentylamine), from the corresponding hydrocarbon analogs. 

Similar to perfluoroalkanesulfonic acids, the yield of the fluorination reaction decreases with the increasing chain length of the starting material. For example, the electrochemical fluorination of acetyl fluoride yields 76% of perfluoroacetyl fluoride, whereas the fluorination of octanoyl fluoride yields only 10% of perfluorooctanoyl fluoride. The yield is also lower when the readily available acid chlorides, and not the fluorides, are employed as starting materials. A major side reaction of the fluorination of acid chlorides such as octanoyl chloride is the formation of cyclic products. Other by-products and impurities present in PFCA fluorides obtained by electrochemical fluorination include short-chain PFCA fluorides, perfluoroalkanes, COFj, and HF. Perfluorooctanoyl fluoride, the most important PFCA, was industrially synthesized from the corresponding chloride despite the lower yield and formation of cyclic by-products. ... 

Many of the perfluoroaLkyl carboxyUc acids were first prepared by the electrochemical fluorination (ECF) of the corresponding carboxyUc acids (7). In ECF acid chlorides are converted to the corresponding perfluoroacid fluorides as shown in equation 1 for octanoyl chloride. 

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 fluorination of acetyl fluoride produces perfluoro-acetyl fluoride in 36-45% yields [85]. Electrochemical fluorination of octanoyl chloride results in perfluorinated 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-Alkyl-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... 

In a later publication [ 129], using the same equipment, Liu et al. describe process improvements in the electrochemical fluorination of octanoyl chloride in which formation of polymeric tar at the anode surface was limited by addition of a mercaptan (1-methyl-1-propanethiol), and by constant current density operation (7 mA cm-2). Continuous operation was achieved by frequent additions of a solution of reactant in hydrogen fluoride. Conversion of reactant to perfluori-nated products was increased to 80%, with good selectivity. 

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