1024-60-8Relevant articles and documents
Catalytic defluorination of perfluorinated aromatics under oxidative conditions using N-bridged diiron phthalocyanine
Colomban, Cédric,Kudrik, Evgenij V.,Afanasiev, Pavel,Sorokin, Alexander B.
supporting information, p. 11321 - 11330 (2014/11/07)
Carbon-fluorine bonds are the strongest single bonds in organic chemistry, making activation and cleavage usually associated with organometallic and reductive approaches particularly difficult. We describe here an efficient defluorination of poly- and perfluorinated aromatics under oxidative conditions catalyzed by the μ-nitrido diiron phthalocyanine complex [(Pc)Fe III(μ-N)FeIV(Pc)] under mild conditions (hydrogen peroxide as the oxidant, near-ambient temperatures). The reaction proceeds via the formation of a high-valent diiron phthalocyanine radical cation complex with fluoride axial ligands, [(Pc)(F)FeIV(μ-N)FeIV(F) (Pc+?)], which was isolated and characterized by UV-vis, EPR, 19F NMR, Fe K-edge EXAFS, XANES, and Kβ X-ray emission spectroscopy, ESI-MS, and electrochemical techniques. A wide range of per- and polyfluorinated aromatics (21 examples), including C6F6, C6F5CF3, C6F5CN, and C6F5NO2, were defluorinated with high conversions and high turnover numbers. [(Pc)FeIII(μ-N)Fe IV(Pc)] immobilized on a carbon support showed increased catalytic activity in heterogeneous defluorination in water, providing up to 4825 C-F cleavages per catalyst molecule. The μ-nitrido diiron structure is essential for the oxidative defluorination. Intramolecular competitive reactions using C6F3Cl3 and C6F3H 3 probes indicated preferential transformation of C-F bonds with respect to C-Cl and C-H bonds. On the basis of the available data, mechanistic issues of this unusual reactivity are discussed and a tentative mechanism of defluorination under oxidative conditions is proposed.
The Preparation and Characterization of Radical Cation Salts Derived from Perfluorobenzene, Perfluorotoluene, and Perfluoronaphthalene
Richardson, T. J.,Tanzella, F. L.,Bartlett, Neil
, p. 4937 - 4943 (2007/10/02)
The salts C6F6+AsF6- (yellow), C6F5CF3- (lime green), and C10F8+AsF6- (dark green) may be prepared by electron oxidation of the appropriate perfluoro aromatic molecule with O2+AsF6-.Other O2+ salts can be similarly employed as can the more strongly oxidizing transition-metal hexafluorides, but salts of the latter are more labile than their AsF- relatives.C6F6+AsF6- is a convenient electron oxidizer (C6F6AsF6+C10F8 -> C10F8AsF6+C6F6) since that which remains from the reaction decomposes at room temperature to volatile products (2C6F6AsF6 -> C6F6+1,4-C6F8+2AsF5).Magnetic susceptibilities for C6F6AsF6 and C10F8AsF6 approximate to Curie law behavior, and g values are close to free-electron values.X-ray diffraction data (single crystal) show C6F6AsF6 to be primitive rhombohedral with a0=6.60 (1) Angstroem, α=106.0 (1) deg, V=246.1 Angstreom3, Z=1, probable space group R3, and (powder data) C10F8AsF6 to be tetragonal with a0=8.27 (5) Angstroem, c0=18.57 (s) Angstroem, V=1270 Angstoem3, Z=4.Salts derived from the monocyclic perfluoro aromatics are thermally unstable but can be kept below -15 deg C.The perfluoronapthalene salts are indefinitely stable at room temperatures.All hydrolyze rapidly.The products of thermal decomposition of the hexafluoroarsenates of the monocyclic cation salts parallel the products of the attack by F-.The latter reaction products are in the molar ratios indicated by the following equations: 2C6F6+ 2F- -> C6F6+ 1,4-C6F8; 2C6F5CF3+ ->2F- -> C6F5CF3+1,3-C6F7CF3.The 1,3-C6F7CF3 isomerizes to a 1:1 mixture with 1,4-C6F7CF3 over several days in the presence of fluoro acids.Mechanisms for the formation of the dienes are discussed.
