- Preparation method 2, 3, 5, 6 - tetrafluoro-phenol
-
The invention discloses a method for preparing 2,3,5,6-tetrafluorophenol. The method comprises the following steps: enabling 2,3,4,5,6-pentafluorobenzoic acid as a raw material to react with inorganicalkali and a phase transfer catalyst in water so as to obtain 4-hydroxy-2,3,5,6-tetrafluorophenol, and performing decarboxylation, thereby obtaining 2,3,5,6-tetrafluorophenol. By adopting the 2,3,4,5,6-pentafluorobenzoic acid as the raw material, the cost of the raw material can be greatly reduced, no special or harsh reaction condition is needed, production equipment is not highly required, nospecial waste is generated, the intermittent is easy to separate, the preparation cost and the labor cost of production can be reduced, and the economic benefits can be increased.
- -
-
Paragraph 0020; 0026-0029
(2020/08/09)
-
- Catalytic defluorination of perfluorinated aromatics under oxidative conditions using N-bridged diiron phthalocyanine
-
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.
- Colomban, Cédric,Kudrik, Evgenij V.,Afanasiev, Pavel,Sorokin, Alexander B.
-
supporting information
p. 11321 - 11330
(2014/11/07)
-
- High throughput 'catch-and-release' synthesis within spatially discrete gel arrays
-
A tetrafluorophenol acrylamide monomer unit was synthesised, co-polymerised and grafted onto a glass slide to form individual gel spots. As a proof of principle study, a small library of amides was rapidly synthesised within these gel spots using 'catch-and-release' chemistry, including the biologically interesting quorum sensing acyl-homoserine lactones. The tetrafluorophenol acrylamide gel provides an efficient platform to synthesise and screen small molecules for biological activity.
- Boehner, Christine M.,Marsden, David M.,Sore, Hannah F.,Norton, David,Spring, David R.
-
supporting information; experimental part
p. 5930 - 5932
(2010/11/21)
-
- A hyperbranched aromatic fluoropolyester for photonic applications
-
A highly fluorinated hyperbranched aromatic polymer was prepared by a mild one-step polyesterification of an AB2 type monomer at room temperature using dicyclohexylcarbodiimide and 4-(dimethylamino)pyridium 4-toluenesulfonate as the condensatio
- Kang, Seok Ho,Luo, Jingdong,Ma, Hong,Barto, Richard R.,Frank, Curtis W.,Dalton, Larry R.,Jen, Alex K.-Y.
-
p. 4355 - 4359
(2007/10/03)
-
- Fragmentation of radical anions of polyfluorinated benzoates
-
A comprehensive study of the symmetry forbidden fragmentation of short-lived radical anions (RAs) has been undertaken for the complete set of polyfluorinated benzoates (C6FnH5-nCO22, n = 1-5). The decay rate constants (kc) of RAs have been determined in aqueous alkaline solution (pH 13.4) by electron photoinjection (EPI) from mercury electrodes and were found to increase dramatically from ≤3 × 103 s-1 (3-F - C6H4CO2-) to (1.2 ± 0.8) × 109 s-1 (C6F5CO2-). The regioselectivity of C-F bond cleavage in the RA fragmentation has been revealed by structure assignment of reduction products of the polyfluorinated benzoic acids by Na, K, and Zn in liquid NH3, as well as by Zn in aqueous NH3 and aqueous alkaline solutions. The kc values depend on the position of the cleaved fluorine to the CO2- group generally in the order para > ortho > meta, and to sharply increase if adjacent fluorine atoms are present. The observed trends reveal that the kinetics of the RA fragmentation reaction is not controlled by the reaction thermodynamics. Semiempirical UHF/INDO calculations, the validity of which has been confirmed by ab initio ROHF/6-31+G calculations, were done to rationalize the observed trends. The reaction transition state (TS) was considered to arise from the RA's and 2*states crossing avoided due to out-of-plane deviation of the cleaving C-F bond. The satisfactory linear correlation (R = 0.96) between the model reaction energy barrier Ea and log kc has been achieved with modeling the local solvation of the CO2- group by its protonation.
- Konovalov, Valery V.,Laev, Sergey S.,Beregovaya, Irina V.,Shchegoleva, Lyudmila N.,Shteingarts, Vitalij D.,Tsvetkov, Yuri D.,Bilkis, Itzhak
-
p. 352 - 361
(2007/10/03)
-