527-21-9Relevant articles and documents
Photoassisted catalytic cleavage of the C-F bond in pentafluorophenol with ZnO and the effect of operational parameters
Ravichandran, Lakshiminarasimhan,Selvam, Kaliyamoorthy,Swaminathan, Meenakshisundaram
, p. 951 - 956 (2007)
The photocatalytic cleavage of the C?F bond in pentafluorophenol (PFP) with ZnO using 254 and 365 nm UV light has been investigated under different conditions. The defluoridation was monitored using an ionometer with a fluoride ion selective electrode. The photocleavage was more effective under 254 nm than under 365 nm UV light. With 254 nm UV light, TiO2-P25, TiO 2 (anatase), ZnO, and ZrO2 photocatalyzed the deflouridation of PFP, whereas CdS, CdO, and SnO2 did not. The defluoridation is enhanced by the addition of oxidants such as KIO4, KClO3, (NH4)2S2O8, and KBrO3. The periodate ion is found to be the most efficient oxidant. The defluoridation intermediates were found to be tetrafluorodihydroxybenzene, trifluorotrihydroxybenzene, and tetrafluoroquinone. CSIRO 2007.
Oxidative degradation of toxic organic pollutants by water soluble nonheme iron(iv)-oxo complexes of polydentate nitrogen donor ligands
Jana, Rahul Dev,Munshi, Sandip,Paine, Tapan Kanti
, p. 5590 - 5597 (2021/05/04)
The ability of four mononuclear nonheme iron(iv)-oxo complexes supported by polydentate nitrogen donor ligands to degrade organic pollutants has been investigated. The water soluble iron(ii) complexes upon treatment with ceric ammonium nitrate (CAN) in aqueous solution are converted into the corresponding iron(iv)-oxo complexes. The hydrogen atom transfer (HAT) ability of iron(iv)-oxo species has been exploited for the oxidation of halogenated phenols and other toxic pollutants with weak X-H (X = C, O, S,etc.) bonds. The iron-oxo oxidants can oxidize chloro- and fluorophenols with moderate to high yields under stoichiometric as well as catalytic conditions. Furthermore, these oxidants perform selective oxidative degradation of several persistent organic pollutants (POPs) such as bisphenol A, nonylphenol, 2,4-D (2,4-dichlorophenoxyacetic acid) and gammaxene. This work demonstrates the utility of water soluble iron(iv)-oxo complexes as potential catalysts for the oxidative degradation of a wide range of toxic pollutants, and these oxidants could be considered as an alternative to conventional oxidation methods.
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.
