Fluorocarbons electrolysis

Fluorocarbons are made commercially also by the electrolysis of hydrocarbons in anhydrous hydrogen fluoride (Simons process) (14). Nickel anodes and nickel or steel cathodes are used. Special porous anodes improve the yields. This method is limited to starting materials that are appreciably soluble in hydrogen fluoride, and is most useflil for manufacturing perfluoroalkyl carboxyflc and sulfonic acids, and tertiary amines. For volatile materials with tittle solubility in hydrofluoric acid, a complementary method that uses porous carbon anodes and HF 2KF electrolyte (Phillips process) is useflil (14). 

Electrolysis of organic sulfides in FIF affords a variety of fluorocarbon derivatives ... 

Lebeau and Damiens obtained the simplest fluorocarbon carbon tetrafluoride (CF4), separating it from fluorine formed at a carbon anode during electrolysis of beryllium difluoride (the first organic product from electrochemical fluorination). 

Jpn. Pat. JP 63-44829 (examined application) Y. Oda, T. Morimoto and K. Suzuki, Ion exchange membrane for electrolysis, Jpn. Pat. JP 63-17913 (examined application) H. Miyake, M. Suhara Y. Sugaya and H. Horie, Novel multilayer membrane for electrolysis, Jpn. Pat. JP 2-12495, A. Kashiwada and T. Hiyoshi, Fluorocarbon cation exchange membrane, Jpn. Pat. JP 3-137136 (examined application) Y.-M. Tsou, J.W. McMichael, R.N. Beaver W.G Beaver and T.J. Piskist, Membrane-electrode structure for electrochemical cells. USPat. 5,203,978 (1993) Y.-M. Tsou, J.W. McMichael, R.N. Beaver and W.G. Beaver, Membrane-electrode structure for electrochemical cells, USPat. 5,336,384, 1994. 

CF2-CF2-0-CF2-CF2-0.1 Application of the Kolb6 reaction to fluorocarbon acids has also continued to attract interest, and reports which have appeared indude (i) electrolysis of the mixture (CF3)2CH C02H-(CF3)2CH-CX>2K to give the compounds CF3-CH CF2, CF3-CH2-CFs, and the expected product (CFs)2CH-CH(CF8)2 (67 %), which is readily dehydrofluorinated to perfluoro-2,3-dimethylbuta-1,3-diene (39%) i" (ii) electrolysis of the add CF8 0-(CF2)2 C02H in MeOH-MeCN (10%) to give mainly the ether CF3-0 (CF2)4 0-CF3 (60%) and (iii) crossed anode electrolysis,i of CFs COsH-EtCXJaH-EtCXlsNa... 

The so-called anode effect on carbon electrodes in fluoride-containing melts is probably the most vivid manifestation of a dielectric FS. This phenomenon was first related to the industrial electrolysis of aluminium in Hall-Heroult cells and, thus, is widely known for more than a 100 years. Nevertheless, a generally acknowledged theory is not achieved yet. Several possible causes have been considered nonwettability of the electrode surface, electrostatic repulsion of the bubbles of the gas evolved at the anode, hydrodynamic crisis of the gas evolution and, finally, the formation of a fluorocarbon dielectric film [18-20]. This latter explanatimi had been developed since then, mainly by Japanese researchers, relatively to the electrochemical production of fluorine [21]. A fluorocarbon film is now widely recognized as a cause of the anode effect both in fluoride and in mixed fluoride-containing electrolytes. 

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