- Preparation method of 3,5-difluoroaniline
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The invention discloses a preparation method of 3,5-difluoroaniline and relates to the technical field of organic synthesis. The preparation method comprises steps as follows: 2,4-difluoroaniline, tap water, hydrochloric acid, bromine, sodium nitrite, sodium monophosphate and ammonium hydroxide are taken as raw materials, cuprous oxide is taken as a catalyst, the tap water and dichloroethane are taken as solvents, and a product of 3,5-difluoroaniline is prepared through steps of bromination, diazotization, ammoniation, extraction, distillation and the like. According to the method, the industrially available raw materials can be utilized for reaction, the process is simple, post-treatment is simple and convenient, conditions are mild, environmental pollution is small, and the product of 3,5-difluoroaniline is prepared with high yield, and meanwhile, industrial production can be realized.
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Paragraph 0028
(2018/02/04)
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- Large-scale preparation of aromatic fluorides via electrophilic fluorination with functionalized aryl- or heteroarylmagnesium reagents
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Functionalized aryl- or heteroarylmagnesium reagents, prepared from the corresponding bromides or iodides using halogen-magnesium exchange or direct magnesium insertion in the presence of lithium chloride, reacted smoothly with N-fluorobenzenesulfonimide, (PhSO2)2NF, in the mixed solvent (4:1 CH2Cl2-perfluorodecalin) to give the corresponding aromatic fluorides in moderate to good yields. Georg Thieme Verlag Stuttgart · New York.
- Yamada, Shigeyuki,Knochel, Paul
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experimental part
p. 2490 - 2494
(2010/09/04)
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- Convenient electrophilic fluorination of functionalized aryl and heteroaryl magnesium reagents
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"Chemical Equation Presented" Cive me an "F": Electrophilic fluorination of various aromatic and heteroaromatic Grignard reagents is smoothly performed with (PhSO2)2NF as fluorinating agent in a 4:1 mixture of CH2Cl2/ perfluorodecalin (see scheme). This solvent system allows minimization of most side reactions.
- Yamada, Shigeyuki,Gavryushin, Andrei,Knochel, Paul
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supporting information; experimental part
p. 2215 - 2218
(2010/06/19)
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- Exploring Structural Opportunities: The Regioflexible Substitution of 1,3-Difluorobenzene
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To demonstrate the superiority of modern organometallic methods, the inexpensive starting material 1,3-difluorobenzene has been selectively converted into the three benzoic acids and all seven bromobenzoic acids containing the two fluorine atoms in homovicinal positions. The 2,6-difluorobenzoic acid (1) was prepared in a one-pot reaction consisting of direct metallation and carboxylation. The key step on the route to the bromobenzoic acid 4 was a deprotonation-triggered bromine migration from the 2- to the 4-position. All other products were attained through (2,6-difluorophenyl)triethylsilane (11). Consecutive deprotonation of the sites adjacent to the fluorine atoms, followed by appropriate electrophilic substitution, provided not only the acid 7 but also the dibromo and iodobromo derivatives 13 and 23. These in turn gave the isomers 14 and 24 upon base-mediated migration of the heaviest halogen, which made the acids 8 and 10 directly accessible. The regiocontrolled monodebromination of intermediate 14 afforded (4-bromo-2,6-difluoro)triethylsilane (15), which opened the route to the acids 3 and 5 (by carboxylation and protodesilylation) and to acid 9 (by carboxylation and bromodesilylation). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Schlosser, Manfred,Heiss, Christophe
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p. 4618 - 4624
(2007/10/03)
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- Method for producing tetrakis ( fluoroaryl) borate-magnesium compound
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Fluoroaryl magnesium halide is reacted with a boron compound so that a molar ratio of the fluoroaryl magnesium halide to the boron compound is not less than 3.0 and not more than 3.7, so as to produce a tetrakis (fluoroaryl) borate·magnesium compound. With this method, there occurs no hydrogen fluoride which corrodes a producing apparatus and requires troublesome waste water treatment.
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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 preparing 3,5-difluoroaniline
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The invention provides a novel process for producing a 3,5-difluoroaniline compound by reacting a 2-halo-4,6-difluoroaniline with a diazotizing agent in the presence of a reducing agent to form a diazonium salt. Build-up of potentially dangerous diazonium salt is avoided by reducing the diazonium salt with the reducing agent, to form a 1-halo-3,5-difluorobenzene, contemporaneously with the diazotization reaction. The 1-halo-3,5-difluorobenzene is then aminated.
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- Preparation of 3-halo-halobenzenes and 1-halo-3,5-dihalobenzenes
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In a process for producing a 3-halo-halobenzene or a 1-halo-3,5-dihalobenzene, a 2-halo-4-haloaniline or 2-halo-4,6-dihaloaniline is mixed with a deaminating agent. The 2-halo-4-haloaniline or 2-halo-4,6-dihaloaniline is deaminated so as to form a corresponding 3-halo-halobenzene or 1-halo-3,5-dihalobenzene.
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- PHOTOCHEMICAL BROMINATION OF ARENES. 2. FLUOROBENZENE DERIVATIVES (1)
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Photochemically induced reaction of fluorobenzene and a range of polyfluorobenzenes, both in an excess of the arene and with fluorotrichloromethane as solvent, gave isolable adducts only with fluorobenzene, the isomeric difluorobenzenes, and in very small yield with 1,3,5-trifluorobenzene.These adducts were identified by combustion analysis, mass spectrometry, and n.m.r. techniques (1H, 13C, 19F).In every case, the expected substitution products accompanied these adducts, and in the more fully fluorinated benzene derivatives substitution was the only process observed.Fluorotrichloromethane encouraged the formation of adducts, but the concurrent formation of substantial amounts of substitution products suggested that adducts are not the necessary precursors of the substitution products, in contrast with other systems.
- Bolton, Roger,Owen, Elaine S. E.
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p. 393 - 406
(2007/10/02)
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