- Decarboxylation of tetrafluorophthalic acid in NH3-enriched high temperature liquid water
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2,3,4,5-Tetrafluorobenzoic acid is an important pharmaceutical intermediate. A green technology for the decarboxylation of tetrafluorophthalic acid to 2,3,4,5-tetrafluorobenzoic acid in NH3-enriched high temperature liquid water (HTLW) was developed. Tetrafluorophthalic acid could undergo the decarboxylation with the catalysis of NH3 to 2,3,4,5-tetrafluorobenzoic acid in HTLW. A conversion of 98.1% and selectivity of 96.5% were achieved at 453.15 K for 1.5 h with an ammonia concentration of 13.4 mmol/L. The effects of ammonia concentration, initial concentration of reactant and reaction temperature were then investigated and correlated using a derivated equation. The results indicated that adequate addition of ammonia could adjust the pH of the reaction medium into 2.2-2.4, where the dominant form of the decarboxylation is the monovalent anion. Moreover, the kinetic data at different temperatures were fitted by a first-order equation, and the rate constants at each temperature and an activation energy of 190 kJ/mol were obtained.
- Fu, Jie,Mo, Jing,Zhang, Jing,Lu, Xiuyang
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- Regiospecific Replacement of Fluorine by Hydrogen in an Aromatic Ring Induced by a Rare Earth Organometallic
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Pentafluorobenzoic acid reacts with YbCp2(dme) to yield, after hydrolysis, 2,3,4,5-tetrafluorobenzoic acid.Conversion is near quantitative with activated magnesium as a coreductant and there is evidence for catalytic turnover in ytterbium on addition of a cyclopentadiene source.Reduction of 2,6-F2C6H3CO2H to o-FC6H4CO2H and of o-FC6H4CO2H to PhCO2H has also been achieved.
- Deacon, Glen B.,Forsyth, Craig M.,Sun, Junhui
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- Preparation of 2,3,4,5-tetrafluorobenzoic acid
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2,3,4,5-Tetrafluorobenzoic acid, an important intermediates of fluoroquinolone antibiotics, was synthesized from tetrachloride phthalic anhydride through imidation, fluorination, hydrolysis and decarboxylation. The effects of phase transfer catalyst on imidation and fluorination reaction and the effects of surfactants on the hydrolysis reaction were studied, respectively. Experimental results showed that the imidation reaction time was greatly reduced in the presence of a phase transfer catalyst, hexadecyltrimethyl, resulting in imidation yield as high as 98.2%. The fluorination yield reached 81.3% when tetrabutylammonium bromide was chosen as a phase transfer catalyst. The hydrolysis reaction time was also decreased by adding hexadecyltrimethyl while increasing the yield to 88.6%. In the post-processing, the sublimation method was used to purify the product, and ideal effect was obtained. In the decarboxylation reaction, tetrafluoride phthalic acid was obtained by decarboxylation in the solvent of tri-n-butyl amine and decarboxylation yield reached 81.6%. Compared with the literature method, the overall reaction time of the improved method decreased from 53 h to 20.5 h and the total yield increased from 47.3% to 57.4%.
- Li, Hua,Wang, Hongkai,Zhao, Ruiju,Liu, Juan,Zhao, Zhengui,Hu, Guoqin,Liang, Zhengyong
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- Regioselective ortho-hydrodefluorination of pentafluorobenzoic acid by low-valent nickel complexes
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2,3,4,5-Tetrafluorobenzoic and 3,4,5-trifluorobenzoic acids were prepared in high yields by reaction of C6F5COOH with zinc in the presence of NiCl2-2′-bipyridine (or 1,10-phenanthroline) complexes.
- Adonin,Starichenko
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- Elemental fluorine. Part 1. Synthesis of fluoroaromatic compounds
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Direct fluorination of 4-fluorobenzoic acid, as a model substrate in a variety of reaction media, shows that 98% formic acid and concentrated sulfuric acid are excellent for promoting electrophilic fluorination. A high degree of fluorination may be achieved using concentrated sulfuric acid, showing that in this medium fluorine will act as a powerful electrophile.
- Chambers, Richard D.,Skinner, Christopher J.,Hutchinson, John,Thomson, Julie
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- Technological method for preparing 2, 3, 4, 5-tetrachloride phthalic anhydride
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The invention relates to an improved technological method for preparing 2, 3, 4, 5-tetrachloride phthalic anhydride. The improved technological method includes bonding 3, 4, 5, 6-tetrafluorophthalic acid and calcium ions in water phases to generate 3, 4, 5, 6-calcium tetrafluorophthalic acid; filtering out solid, then removing single-molecule calcium carbonate in water environments under the catalytic effect of specific strong acid and strong alkali salts to generate 2, 3, 4, 5-tetrachloride phthalic anhydride; continuing to carry out reaction on the generated 2, 3, 4, 5-tetrachloride phthalicanhydride and calcium carbonate to generate corresponding salt and releasing carbon dioxide; regulating pH (potential of hydrogen) values of water phases after the reaction is completely carried out;cooling and filtering the generated 2, 3, 4, 5-tetrachloride phthalic anhydride to obtain final finished products. The 3, 4, 5, 6-tetrafluorophthalic acid is used as a starting material. The improvedtechnological method has the advantages that the improved technological method is high in decarboxylation reaction yield and suitable for industrialization production, organic solvents can be omitted, waste gas, wastewater and industrial residues are easy to treat, and the like.
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Paragraph 0039-0044; 0061
(2018/05/01)
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- Method for preparing 2,3,4,5-tetrafluoro benzoic acid and 1,2,3,4-tetrafluorobenzene
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The present invention discloses a method for preparing 2,3,4,5-tetrafluoro benzoic acid and 1,2,3,4-tetrafluorobenzene through a decarboxylation reaction of tetrafluoro phthalic acid at a reaction temperature of 180-250 DEG C in an ammonia-containing high-temperature liquid-state water medium. The method of the present invention has characteristics of high decarboxylation reaction rate, short decarboxylation reaction time, high yield, and green environmental protection.
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Paragraph 0037; 0038
(2016/11/28)
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- Gold(I)-catalyzed protodecarboxylation of (Hetero)aromatic carboxylic acids
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Readily available, inexpensive and easy to handle, carboxylic acids have been shown to be very effective, greener coupling partners compared to costly organometallic reagents for the formation of C-C bonds. The use of well-defined gold complexes furnished 3 in slightly better yield with butyric acid, and in quantitative yield with adamantane-1-carboxylic acid. All reactions reached completion within 16 h. As with silver systems, this reactivity trend highlights, as previously observed, the benefits of potential coordinating groups in the ortho position to the gold binding site, which possibly facilitate the decarboxylation step. Additional reaction time and increased temperatures were necessary to afford the gold aryl products in satisfactory yields. Yet, some substrates such as 2-nitrobenzoic acids reacted poorly and could only be transformed in 50% yield.
- Dupuy, Stéphanie,Nolan, Steven P.
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supporting information
p. 14034 - 14038
(2013/11/19)
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- Catalytic C-F bond activation of perfluoroarenes by tricoordinated gold(I) complexes
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We report the first example of gold catalyzing C-F bond activation for perfluoroarenes in the presence of silanes. Tricoordinated gold(I) complexes supported by Xantphos-type ligands, such as Xantphos and tBuXantphos ligands, exhibit efficacy in the hydrodefluorination (HDF) of various types of perfluoroarenes. For [tBuXantphosAu(AuCl2)], the highest turnover number is up to 1000 in the HDF of pentafluoronitrobenzene with diphenylsilane. An examination of functional group tolerance shows the orthogonality of this gold(I) catalytic protocol to ketone, ester, carboxylate, alkynyl, alkenyl and amide groups, suggesting its potential application in chemoselective C-F activations. Mechanistic studies show that the equilibrium between tetracoordinated [L2Au]+ and [LAu]+ is important for the reactivity of gold catalysts, which is dependent on the sterically bulky group of Xantphos-type ligands. Furthermore, computational studies for the possible reaction pathways suggest that direct oxidative addition of C-F bonds by gold(I) cation might be the key step during these catalytic reactions. Copyright
- Zhan, Jin-Hui,Lv, Hongbin,Yu, Yi,Zhang, Jun-Long
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experimental part
p. 1529 - 1541
(2012/07/14)
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- Process for making benzoic acids
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A process of producing benzoic acids from phthalimides is described. The ability to dramatically reduce the reaction time in comparison to currently practiced processes by the addition of readily available compounds is demonstrated.
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- Fragmentation of radical anions of polyfluorinated benzoates
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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
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p. 352 - 361
(2007/10/03)
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- Processes for producing tetrafluorophthalic anhydride and fluorobenzoic acids
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A process for producing tetrafluorophthalic anhydride, which comprises chlorinating tetrachlorophthalic anhydride to obtain 3,3,4,5,6,7-hexachloro-1-[3H]-isobenzofuranone, then fluorinating it to obtain 3,4,5,6-tetrafluorophthaloyldifluoride and/or 3,3,4,5,6,7-hexafluoro-1-[3H]-isobenzofuranone, and further reacting the tetrafluorophthalolyldifluoride and/or the hexafluoro-1-[3H]-isobenzofuranone with an inorganic base or an organic acid to obtain tetrafluorophthalic anhydride.
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- Process for the preparation of tetrafluorophthalic acid and/or tetrafluorophthalic anhydride
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The present invention relates to a process for the preparation of tetrafluorophthalic acid and/or tetrafluorophthalic anhydride by reacting a compound of the formula STR1 in which X is a radical STR2 which is optionally mono- or polysubstituted on the aromatic nucleus by fluorine and/or chlorine and/or alkyl groups having 1 to 4 carbon atoms, or is a radical STR3 in which R1, R2 and R3 are as defined, with water, and subsequently removing the water still present by azeotropic distillation or extracting the tetrafluorophthalic acid and/or its anhydride with a water-insoluble solvent or solvent mixture.
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- Process for the preparation of 2,3,4,5-tetrafluorobenzoic acid
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A process for the preparation of 2,3,4,5,-tetrafluorobenzoic acid of the formula (1) STR1 by heating N'-substituted N-aminotetrafluorophthalimides of the formula (2) STR2 in which X is the radical STR3 where R1, R2 are a hydrogen atom, an alkyl-(C1 -C10)- group, aryl group, alkyl-(C1 -C6)-Co- group or aryl-CO- group, it being possible for the aryl or aryl-CO- group in the case of R1 and R2 to be substituted on the aromatic ring by fluorine and/or chlorine atoms and/or alkyl-(C1 -C4)-groups, or R1 and R2 together are a phthaloyl radical which can be substituted on the aromatic ring by 4 chlorine atoms or 4 fluorine atoms, or where X is the radical STR4 which can be substituted on the aromatic ring by fluorine and/or chlorine atoms and/or alkyl-(C1 -C4)- groups, in an aqueous medium at pH values of approximately -1 to approximately +1 at temperatures of approximately 160 to approximately 220° C.
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- SYNTHESIS OF AN AMINOISOXAZOLIDINE SUBSTITUTED QUINOLONE ACID
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New heterocycle aminoisoxazolidine 7 and tetrafluorobenzoic acid are synthesized for the synthesis of a quinolone antibacterial agent.The synthesis of a chiral aminoisoxazolidine substituted quinolone acid, U-82662A, is described.
- Kim, Kyoung Soon
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- Method for production of 2,3,4,5-tetrafluorobenzoic acid
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A method for the production of 2,3,4,5-tetrafluorobenzoic acid, which comprises effecting said production by decarbonating 3,4,5,6-tetrafluorophthalic acid in an aqueous medium adjusted to a pH in the range of 0.7 to 2.2 at a temperature in the range of 100° to 220° C.
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- Process for tetrafluorobenzoic acid
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An improved process for the preparation of 2,3,4,5-tetrafluorobenzoic acid is described which involves decarboxylation of tetrafluorophthalic acid in the presence of a base catalyst. Also described is an improved method for preparing tetrafluorophthalic acid and, in turn, a one-pot process for tetrafluorobenzoic acid using the combination of the two improvements.
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- Process for the preparation of 2,3,4,5-tetrafluorobenzoyl acetates
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An improved process for the preparation of methyl 2,3,4,5-tetrafluorobenzoylacetate is described. The process is for intermediates that lead to trifluoroquinolinic acids which in turn are used to produce antibacterial agents of the difluoro quinolinecarboxylic acid type. The process runs at room temperature, uses a safe and inexpensive base, and can be conveniently scaled up for manufacturing purposes.
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- OXIDATION OF OCTAFLUORONAPHTHALENE AND HEPTAFLUORONAPHTHOLS WITH HYDROGEN PEROXIDE
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Derivatives of 1-oxodihydronaphthalenes and 1,4-naphthoquinone are formed preferentially during the thermal decomposition of hydrogen peroxide in an excess of octafluoronaphthalene or heptafluoro-1- and heptafluoro-2-naphthols.The oxidation of these substrates with an excess of hydrogen peroxide leads to destruction of the aromatic ring.Possible paths to the formation of the main products, including the generation of heptafluoronaphthoxyl radicals both as a result of reaction of the octafluoronaphthalene with the hydroxyl radicals and as a result of oxidation of the heptafluoronaphthols, are considered.
- Bogachev, A. A.,Kobrina, L. S.,Yakobson, G. G.
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p. 2307 - 2313
(2007/10/02)
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- SOME REACTIONS OF PHENYLENE- AND POLYPHENYLENE-MERCURIALS
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Cleavage reactions of six phenylene- and polyphenylene-mercury heterocycles with the mercuric halides and mercuric acetate in suitable refluxing solvents readily produce 1,2-C6X4(HgX)2; 2,2'-C6H4C6H4(HgX)2 and 2,2''-C6H4C6H4C6H4(HgX)2 (X = Cl, Br, I or CH3CO2).Addition of silver acetate to 2,2'-C6H4C6H4(HgBr)2 gives 2,2'-C6H4C6H4(HgO2CCH3)2 which reacts with concentrated hydrochloric acid to form 2,2'-C6H4C6H4(HgCl)2.Treatment with sodium iodide, or in some cases simply the application of heat under vacuum, causes symmetrization of these cleavage products back to the original heterocycles in high yield.The terphenylenemercury dimer, (C6H4C6H4C6H4Hg)2, forms solvates with a wide variety of donor and non-donor solvents.Pyrolysis of mercuric 2,3,4,5-tetrafluorobenzoate at 190 deg.C. yields 2-mercurio-3,4,5,6-tetrafluorobenzoate and 2,3,4,5-tetrafluorobenzoic acid; at 300 deg.C. the former gives tetrafluorophenylenemercury, (C6F4Hg)3.
- Massey, A. G.,Al-Jabar, N. A. A.,Humphries, R. E.,Deacon, G. B.
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- Organolanthanoids. IV. Some Reactions of Bis(polyfluorophenyl)ytterbium Compounds
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From reactions of bis(polyfluorophenyl)ytterbium compounds R2Yb (R=C6F5 or p-HC6F4) with trans-Rh(CO)Cl(PPh3)2, NiCl2(bpy) (bpy=2,2'-bipyridyl), NiCl2(PPh3)2, PtCl2(bpy), triphenyltin chloride, iodine and mercuric chloride, the polyfluorophenyl derivatives trans-RRh(CO)(PPh3)2, R2Ni(bpy), trans-(C6F5)2Ni(PPh3)2, (C6F5)2Pt(bpy), Ph3SnC6F5, C6F5I and (C6F5)2Hg have been obtained.Reduction to mercury metal accompanied formation of the last compound.Carbonation of (C6F5)2Yb in tetrahydrofuran followed by acidification yields pentafluorobenzoic acid and, surprisingly, a significant amount of 2,3,4,5-tetrafluorobenzoic acid, in which the aromatic hydrogen is substantially derived from tetrahydrofuran.Reaction of (C6F5)2Yb with pentafluorobenzoic acid followed by acidification also gives 2,3,4,5-tetrafluorobenzoic acid.Fluoride elimination is less extensive and less specific in a similar reaction of YbI2.
- Deacon, Glen B.,Mackinnon, Peter I.,Tuong, Tran D.
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