- Optimized synthesis of tetrafluoroterephthalic acid: A versatile linking ligand for the construction of new coordination polymers and metal-organic frameworks
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Pure 2,3,5,6-tetrafluoroterephthalic acid (H2tfBDC) is obtained in high yields (95%) by reacting 1,2,4,5-tetrafluorobenzene with a surplus (>2 equiv) of n-butyllithium in tetrahydrofuran (THF) and subsequent carbonation with CO2 without any extensive purification procedure. A single crystal X-ray structure analysis of H2tfBDC (1) confirms former data obtained for a deuterated sample (P1, Z= 1). Recrystallization from water/acetone leads to single crystals of H2tfBDC · 2H2O (2, P21/c, Z= 2), where an extensive hydrogen bonding network is found. By reacting H2tfBDC with an aqueous ammonia solution, single crystals of (NH4)2tfBDC (3, C2/m, Z= 2) are obtained. 3 is thermally stable up to 250 °C and shows an enhanced solubility in water compared to H2tfBDC. Monosubstituted 2,3,5,6-tetrafluorobenzoic acid (H2tfBC, 4) is obtained by reacting 1,2,4,5-tetrafluorobenzene with stoichiometric amounts (1 equiv) of n-butyllithium in THF. Its crystal structure (Fdd2, Z= 16) shows dimeric units as characteristic structural feature.
- Orthaber, Andreas,Seidel, Christiane,Belaj, Ferdinand,Albering, Joerg H.,Pietschnig, Rudolf,Ruschewitz, Uwe
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Read Online
- Lanthanide tetrafluorobenzoates as emitters for OLEDs: New approach for host selection
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Brightly luminescent and highly soluble lanthanide tetrafluorobenzoates, as well as their mixed ligand complexes, were synthesized and thoroughly characterized. The low charge carrier mobility hampered their use in OLED, but this problem was overcome by a
- Utochnikova, Valentina V.,Solodukhin, Nikolay N.,Aslandukov, Andrey N.,Marciniak, Lukasz,Bushmarinov, Ivan S.,Vashchenko, Andrey A.,Kuzmina, Natalia P.
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Read Online
- Direct evidence of edge-to-face CH/π interaction for PAR-1 thrombin receptor activation
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Heptapeptide SFLLRNP is a receptor–tethered ligand of protease-activated receptor 1 (PAR-1), and its Phe at position 2 is essential for the aggregation of human platelets. To validate the structural elements of the Phe-phenyl group in receptor activation, we have synthesized a complete set of S/Phe/LLRNP peptides comprising different series of fluorophenylalanine isomers (Fn)Phe, where n = 1, 2, 3, and 5. Phe-2-phenyl was strongly suggested to be involved in the edge-to-face CH/π interaction with the receptor aromatic group. In the present study, to prove this receptor interaction definitively, we synthesized another series of peptide analogs containing (F4)Phe-isomers, with the phenyl group of each isomer possessing only one hydrogen atom at the ortho, meta, or para position. When the peptides were assayed for their platelet aggregation activity, S/(2,3,4,6-F4)Phe/LLRNP and S/(2,3,4,5-F4)Phe/LLRNP exhibited noticeable activity (34% and 6% intensities of the native peptide, respectively), whereas S/(2,3,5,6-F4)Phe/LLRNP was completely inactive. The results indicated that, at the ortho and meta positions but not at the para position, benzene-hydrogen atoms are required for the CH/π interaction to activate the receptor. The results provided a decisive evidence of the molecular recognition property of Phe, the phenyl benzene-hydrogen atom of which participates directly in the interaction with the receptor aromatic π plane.
- Asai, Daisuke,Inoue, Naoko,Sugiyama, Makiko,Fujita, Tsugumi,Matsuyama, Yutaka,Liu, Xiaohui,Matsushima, Ayami,Nose, Takeru,Costa, Tommaso,Shimohigashi, Yasuyuki
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- Photo-induced deep aerobic oxidation of alkyl aromatics
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Oxidation is a major chemical process to produce oxygenated chemicals in both nature and the chemical industry. Presently, the industrial manufacture of benzoic acids and benzene polycarboxylic acids (BPCAs) is mainly based on the deep oxidation of polyalkyl benzene, which is somewhat suffering from environmental and economical disadvantage due to the formation of ozone-depleting MeBr and corrosion hazards of production equipment. In this report, photo-induced deep aerobic oxidation of (poly)alkyl benzene to benzene (poly)carboxylic acids was developed. CeCl3 was proved to be an efficient HAT (hydrogen atom transfer) catalyst in the presence of alcohol as both hydrogen and electron shuttle. Dioxygen (O2) was found as a sole terminal oxidant. In most cases, pure products were easily isolated by simple filtration, implying large-scale implementation advantages. The reaction provides an ideal protocol to produce valuable fine chemicals from naturally abundant petroleum feedstocks. [Figure not available: see fulltext.].
- Wang, Chang-Cheng,Zhang, Guo-Xiang,Zuo, Zhi-Wei,Zeng, Rong,Zhai, Dan-Dan,Liu, Feng,Shi, Zhang-Jie
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p. 1487 - 1492
(2021/07/10)
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- Preparation method of 2, 3, 5, 6-tetrafluorobenzoic acid
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The invention relates to a preparation method of 2, 3, 5, 6-tetrafluorobenzoic acid and belongs to the field of preparation of fine chemical products. The method comprises that zinc powder and pentafluorobenzoic acid undergo a reaction in aqueous ammonia
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Paragraph 0036; 0037; 0038; 0039; 0040; 0041; 0042; 0043
(2018/03/24)
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- Photocyclodehydrofluorination
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Mallory-type photocyclization involves a series of photoreactions of stilbenes, o-terphenyls and related derivatives, which undergo intramolecular cyclization via dihydrophenanthrene intermediates. In typical Mallory photocyclizations, oxidants are usually needed to produce the final phenanthrene-containing product. In the research described here, appropriately fluorinated stilbenes and o-terphenyls undergo ring closure and HF is eliminated. This photocyclodehydrofluorination (PCDHF) reaction is very useful to produce a wide range of selectively fluorinated polynuclear aromatic hydrocarbons that possess a phenanthrene (or heterocyclic analogue of phenanthrene) substructure. These fluorinated products are of great interest in various aspects of the materials science.
- Li, Zhe,Twieg, Robert J.
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supporting information
p. 15534 - 15539
(2015/11/03)
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- CARBOXYLATION CATALYSTS
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The use of a complex of the form Z—M—OR in the carboxylation of a substrate is described. The group Z is a two-electron donor ligand, M is a metal and OR is selected from the group consisting of OH, alkoxy and aryloxy. The substrate may be carboxylated at a C—H or N—H bond. The metal M may be copper, silver or gold. The two-electron donor ligand may be a phosphine, a carbene or a phosphite ligand. Also described are methods of manufacture of the complexes and methods for preparing isotopically labelled caboxylic acids and carboxylic acid derivatives.
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Paragraph 0093; 0095
(2013/04/13)
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- π-π Interaction assisted hydrodefluorination of perfluoroarenes by gold hydride: A case of synergistic effect on C-F bond activation
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Synergistic effect is prevalent in natural metalloenzymes in activating small molecules, and the success has inspired the development of artificial catalysts capable of unprecedented organic transformations. In this work, we found that the attractive π-π interaction between organic additives (as electron-donors) and the perfluorinated arenes (as electron acceptors) is effective in gold hydride catalyzed activation of C-F bonds, specifically hydrodefluorination (HDF) of perfluoroarenes catalyzed by the Sadighi's gold hydrides [(NHC)AuH] (NHC = N-heterocyclic carbene). Although a weak interaction between [(NHC)AuH] and perfluoroarenes was observed from 1H NMR and UV-vis spectroscopies, low reactivity of [(NHC)AuH] toward HDF was found. In contrast, in the presence of p-N,N-dimethylaminopyridine (DMAP), the HDF of perfluoroarenes with silanes can be efficiently catalyzed by [(NHC)AuH], resulting in mainly the para-hydrodefluorinated products with up to 90% yield and 9 turnovers. The yield of the reaction increases with the more electron-withdrawing groups and degree of fluorination on the arenes, and the HDF reaction also tolerates different function groups (such as formyl, alkynyl, ketone, ester, and carboxylate groups), without reduction or hydrogenation of these function groups. To reveal the role of DMAP in the reactions, the possible π-π interaction between DMAP and perfluoroarenes was suggested by UV-vis spectral titrations, 1H NMR spectroscopic studies, and DFT calculations. Moreover, 1H and 19F-NMR studies show that this π-π interaction promotes hydrogen transfer from [(NHC)AuH] to pyridyl N atom, resulting in C-F bond cleavage. The interpretation of π-π interaction assisted C-F activation is supported by the reduced activation barriers in the presence of DMAP (31.6 kcal/mol) than that in the absence of DMAP (40.8 kcal/mol) for this reaction. An analysis of the charge distribution and transition state geometries indicate that this HDF process is controlled by the π-π interaction between DMAP and perfluoroarenes, accompanied with the changes of partial atomic charges.
- Lv, Hongbin,Zhan, Jin-Hui,Cai, Yuan-Bo,Yu, Yi,Wang, Bingwu,Zhang, Jun-Long
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supporting information
p. 16216 - 16227,12
(2020/09/09)
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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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- Synthesis of tetrafluorinated aromatic amino acids with distinct signatures in 19F NMR
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Fluorinated amino acids serve as powerful tools in protein chemistry. We synthesized a series of para-substituted tetrafluorophenylalanines via the regioselective SNAr chemistry of the commercially available pentafluorophenylalanine Boc-Z. Thes
- Qin, Luoheng,Sheridan, Christopher,Gao, Jianmin
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scheme or table
p. 528 - 531
(2012/03/26)
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- Carboxylation of N-H/C-H bonds using n-heterocyclic carbene copper(I) complexes
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Greenhouse gas makes good: A simple copper-mediated protocol has been developed where N-H or C-H bonds can be directly functionalized using an easily prepared catalyst. The novel [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] copper(I) hydroxide, [Cu(IPr)(OH)], permits the facile activation and carboxylation of N-H and C-H bonds with pKavalues of less than 27.7 (see scheme).
- Boogaerts, Ine I. F.,Fortman, George C.,Furst, Marc R. L.,Cazin, Catherine S. J.,Nolan, Steven P.
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supporting information; scheme or table
p. 8674 - 8677
(2011/01/06)
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- Carboxylation of C-H bonds using N -heterocyclic carbene gold(I) complexes
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A highly efficient [(NHC)AuI]-based (NHC = N-heterocyclic carbene) catalytic system for the carboxylation of aromatic and heteroaromatic C-H bonds was developed. The significant base strength of the Au-OH species is at the origin of the activation process and permits the facile functionalization of C-H bonds without the use of other organometallic reagents.
- Boogaerts, Ine I. F.,Nolan, Steven P.
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supporting information; experimental part
p. 8858 - 8859
(2010/08/21)
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- Structure-function relationships in liquid-crystalline halogen-bonded complexes
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New liquid-crystalline materials were prepared by self-assembly driven by halogen bonding between a range of 4-alkoxystilbazoles, 4-alkyl-, and 4-alkoxy-substituted pyridines as halogen-bonding acceptors, and substituted derivatives of4-iodotetrafluorophenyl as halogen-bonding donors. Despite the fact that the starting materials are not mesomorphic, the dimeric, halogen-bonded complexes obtained exhibited nemetic and SmA phases, depending on the length of the alkylchains present on the components. The modularity of this approach also led to new chiral mesogens starting from non-mesomorphic chiral compounds.
- Bruce, Duncan W.,Metrangolo, Pierangelo,Meyer, Franck,Pilati, Tullio,Praesang, Carsten,Resnati, Giuseppe,Terraneo, Giancarlo,Wainwright, Stephen G.,Whitwood, Adrian C.
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supporting information; experimental part
p. 9511 - 9524
(2010/12/20)
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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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- Process for decarboxylation of halogenated aromatic carboxylic acids
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Halogenated aromatic carboxylic acids are decarboxylated by heating them in the presence of water at temperatures of 80° to 180° C. and in the presence of water and other acids at temperatures above 80° C.
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- Reductive dehalogenation of polyfluoroarenes by zinc in aqueous ammonia
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Aqueous ammonia has been found to be a good and versatile medium for the highly selective hydrodehalogenation of polyfluoroarenes by zinc under unprecedentedly mild conditions. The reduction of pentafluorobenzoic acid, 2,3,4,5,6-pentafluorobenzyl alcohol, pentafluorobenzamide, pentafluoropyridine, heptafluoro-2-naphthoic acid, 1,3,4,5,7,8-hexafluoro-2-naphthoic acid, octafluoronaphthalene, octafluorotoluene, decafluorobiphenyl, chloropentafluorobenzene and 4-chlorotetrafluorobenzoic acid give products derived from the removal of one or two halogen atoms. A reduction mechanism, proceeding through electron capture to give a radical anion and then fragmentation of the latter, has been suggested. The observed high selectivity of the process suggests a radical anion formed by direct electron transfer from zinc to substrate. The dehalogenation regioselectivity is basically in accordance with that expected for radical anion fragmentation.
- Laev, Sergey S.,Shteingarts, Vitalii D.
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p. 175 - 185
(2007/10/03)
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- Direct conversion of perfluoroalkanes and perfluoroarenes to perfluoro Grignard reagents
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Magnesium anthracene selectively reduces C6F12 or C6F6 and CF3C6F11 or CF3C6F5 to C6F5MgF and CF3C6F4MgF, respectively.
- Beck, Christopher M.,Park, You-Jung,Crabtree, Robert H.
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p. 693 - 694
(2007/10/03)
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- Decarboxylation process
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A process for the monodecarboxylation of a halogenated aromatic dicarboxylic acid or derivative thereof in which the halogenated aromatic dicarboxylic acid or derivative thereof in a liquid medium is heated characterized in that the liquid medium is a pol
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- Reductive defluorination of polyfluoroarenes by zinc in aqueous ammonia
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Aqueous ammonia has been found to be a good and versatile medium for the reductive defluorination of polyfluoroarenes by zinc. Upon the reduction of pentafluorobenzoic acid, 2,3,4,5,6-pentafluorobenzyl alcohol, pentafluoropyridine and heptafluoro-2-naphthoic acid individual products derived from the removal of one fluorine atom have been obtained.
- Laev, Sergey S.,Shteingarts, Vitalij D.
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p. 3765 - 3768
(2007/10/03)
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- On the difference in the results of reductive defluorination of pentafluorobenzoic acid by sodium and zinc in liquid ammonia medium
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Under the reduction of pentafluorobenzoic acid in liquid ammonia by sodium the deep defluorination with removal of three or more fluorine atoms has been observed, whereas with zinc only the product of para-defluorination has been obtained.
- Laev,Laev, Sergey S.,Shteingarts,Shteingarts, Vitalij D.,Bilkis,Bilkis, Isaak I.
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p. 4655 - 4658
(2007/10/02)
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- Halogenated esters
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Compounds of formula (I), useful as insecticides and knockdown agents: STR1 where Y is C1-6 alkoxy, Z is halo or C1-6 alkoxy; R is --(CH2)p --(O)m --R3 where m and p may be 0 or 1; R3
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- Process for the preparation of 2,3,5,6-tetrafluorobenzoic acid
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2,3,5,6-Tetrafluorobenzoic acid is prepared by hydrogenolysis of pentafluorobenzoic acid (esters).
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- Process for the preparation of 2,3,5,6-tetrafluorobenzoic acid, and the new compounds 2,3,5,6-tetrachloro-4-trifluoromethyl-benzoyl chloride and 2,3,5,6-tetrafluoro-4-trifluoromethyl-benzoyl fluoride
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2,3,5,6-Tetrafluorobenzoic acid is prepared from 4-trifluoromethyl-benzoyl fluoride by chlorination, fluorination, hydrolysis, decarboxylation and saponification. The new compounds 2,3,5,6-tetrachloro-4-trifluoromethyl-benzoyl chloride and 2,3,5,6-tetrafluoro-4-trifluoromethyl-benzoyl fluoride are produced during this as intermediates.
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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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