367-23-7Relevant articles and documents
Synthesis of fluorophenyl carbonyl cobalt(I) complexes and decarbonylation of 2,4,5-trifluorobenzaldehyde catalyzed by CoMe(PMe3)4
Yuan, Shuo,Sun, Hongjian,Zhang, Shumiao,Li, Xiaoyan
, p. 100 - 105 (2016)
Three fluorophenyl carbonyl cobalt(I) complexes PhF(PMe3)3Co(CO) (1-3) were synthesized by the reaction of fluoro-benzaldehydes with CoMe(PMe3)4 via C-H bond activation and decarbonylation reaction. The dicarbonyl cobalt(I) complex (2,4-F2C6H3)Co(CO)2(PMe3)2 (4) was obtained by reacting of complex 1 with CO. Complex 1 reacted with pentafluorobromobenzene afforded cobalt(II) bromide (2,4-F2C6H3)Co(Br)(PMe3)3 (5) with the formation of perfluorinated diphenyl. The reaction of complex 3 and phenylacetylene delivered the hydrido diethinyl cobalt(III) complex (PhCC)2Co(H)(PMe3)3 (6) with 1,2,4-trifluorobenzene as a byproduct. The molecular structures of 1, 4 and 5 were determined by X-ray diffraction. Furthermore, we found that CoMe(PMe3)4 could be used as a catalyst for the catalytic decarbonylation of 2,4,5-trifluorobenzaldehyde with triethylsilane as a hydrogen source.
Novel preparation method of 2, 4, 5-trifluorophenylacetic acid
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, (2021/06/23)
The invention discloses a novel preparation method of 2, 4, 5-trifluorophenylacetic acid, which belongs to the technical field of preparation of medical intermediates, and comprises the following preparation steps: carrying out nitration reaction on sulfuric acid and m-dichlorobenzene to obtain an intermediate II; adding the intermediate II, a phase transfer catalyst and potassium fluoride into an aprotic solvent to obtain an intermediate III; performing hydrogenation reaction on the intermediate III to obtain an intermediate IV; carrying out diazotization reaction on the intermediate IV, nitrosyl sulfuric acid and sodium fluoborate to obtain an intermediate V; performing cracking reaction on the intermediate V to obtain an intermediate VI; carrying out reduction reaction on the intermediate VI, and then carrying out bromination reaction on the intermediate VI and liquid bromine to obtain an intermediate VII; subjecting the intermediate VII to a substitution reaction with diethyl malonate, and obtaining 2, 4, 5-trifluorophenylacetic acid after hydrolysis and purification. A novel synthesis route is provided, the problem that technological operation is tedious is solved, the requirements for reaction and operation conditions are low, anhydrous and oxygen-free reaction conditions are not needed, the method is suitable for industrial production, and the yield and purity are greatly improved.
Preparation method of 1, 2, 4-trifluorobenzene
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, (2021/01/28)
The invention relates to the technical field of preparation of chemical drug intermediates, and particularly discloses a preparation method of 1, 2, 4trifluorobenzene. The preparation method comprisesthe following steps: step 1, preparing 2, 4-diamino fluorobenzene: carrying out hydrogenation reduction on 2, 4-dinitrofluorobenzene and a catalyst to obtain 2, 4-diamino fluorobenzene with a reaction formula shown in the specification; step 2, preparation of fluoroboric acid diazonium salt: 2, 4-diamino fluorobenzene obtained in the step 1 is subjected to diazotization reaction with a fluoroboric acid aqueous solution and a sodium nitrite aqueous solution in sequence, a fluoroboric acid diazonium salt intermediate is obtained, and the reaction formula is shown in the specification; and step3, preparation of 1, 2, 4-trifluorobenzene: heating and decomposing the fluoroboric acid diazonium salt intermediate obtained in the step 2 to obtain 1, 2, 4-trifluorobenzene, nitrogen and boron trifluoride gas, and the reaction formula is shown in the specification. The method has the advantages that the raw materials are cheap and easy to obtain, the preparation cost is low, the yield is high, few three wastes are produced during preparation, and the economic value of byproducts is high.
PROCESS FOR THE PREPARATION OF 1-BROMO-2,4,5-TRIFLUOROBENZENE
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Page/Page column 12; 16-17, (2021/09/17)
The present invention relates to a process for the preparation of l-bromo-2,4,5-trifluorobenzene from 2,4,5-trifhioroaniline or sulfate salt thereof. The present invention also relates to a process for the preparation of 1,2,4-trifluorobenzene from 2,4,5-trifluoroaniline and then converting into 1-bromo-2,4,5 -trifluorobenzene.
Synthetic method for 1,2,4-trifluorobenzene
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, (2019/12/08)
The invention provides a synthetic method for 1,2,4-trifluorobenzene, belongs to the field of pesticide, medicine, and liquid crystal material intermediate preparation, and solves the problem of harshreaction conditions of a current method for synthesizing 1,2,4-trifluorobenzene. The synthetic method for the 1,2,4-trifluorobenzene is characterized by comprising the following steps: performing nitration by using 2,4-dichlorofluorobenzene as a raw material and nitric acid as a nitrating agent to form 2,4-dichloro-5-fluoronitrobenzene in the presence of sulfuric acid; dissolving the 2,4-dichloro-5-fluoronitrobenzene into an organic solvent, adding potassium fluoride and a first catalyst, and performing fluorination under the catalysis of the first catalyst to obtain 2,4,5-trifluoronitrobenzene; dissolving the 2,4,5-trifluoronitrobenzene into a solvent, and performing hydrogenation reduction with hydrogen under the catalysis of a second catalyst to obtain 2,4,5-trifluoroaniline; and performing a reaction on the 2,4,5-trifluoroaniline and sulfuric acid, after a salt is formed, performing a diazotization reaction on the salt and nitroso-sulfuric acid, performing a deamination reductionreaction with sodium hypophosphite under the catalysis of a copper salt, and finally performing steam distillation to obtain the 1,2,4-trifluorobenzene. The method provided by the invention has the advantages of mild reaction conditions and the like
Hydrodefluorination of functionalized fluoroaromatics with triethylphosphine: A theoretical and experimental study
Facundo, Aldo A.,Arévalo, Alma,Fundora-Galano, Gabriela,Flores-álamo, Marcos,Orgaz, Emilio,García, Juventino J.
, p. 6897 - 6908 (2019/05/17)
Recently we reported the metal free hydrodefluorination of selected fluoroaromatics using triethylphosphine as the sole defluorinating agent. That prompted us to evaluate the mechanistic proposal and in the light of these results, along with new experimental evidence, we have now modified the initial proposal. The new mechanism avoids the highly energetic β-elimination step of roughly 71 kcal mol-1 for hexafluorobenzene and pentafluoropyridine at 393.15 K, invoking the participation of water. The use of D2O confirmed the role of water as the hydrogen source, yielding the corresponding deutero-defluorinated products; DFT calculations agree with this new proposed mechanism. We also report herein the use of this one-pot hydrodefluorination method applied to a broader number of fluoroaromatic derivatives; some of them allowed the collection of key mechanistic evidence.
NHC·Alane Adducts as Hydride Sources in the Hydrodefluorination of Fluoroaromatics and Fluoroolefins
Schneider, Heidi,Hock, Andreas,Jaeger, Alma D.,Lentz, Dieter,Radius, Udo
, p. 4031 - 4043 (2018/09/11)
We present herein the utilization of NHC-stabilized alane adducts of the type (NHC)·AlH3 [NHC = Me2Im (1), Me2ImMe (2), iPr2Im (3), iPr2ImMe (4), Dipp2Im (5)] and (NHC)·AliBu2H [NHC = iPr2Im (6), Dipp2Im (7)] as novel hydride transfer reagents in the hydrodefluorination (HDF) of different fluoroaromatics and hexafluoropropene. Depending on the alane adduct used, HDF of pentafluoropyridine to 2,3,5,6-tetrafluoropyridine in yields of 15–99 % was observed. The adducts 1, 2, and 5 achieved a quantitative conversion into 2,3,5,6-tetrafluoropyridine at room temperature immediately after mixing the reactants. Studies on the HDF of fluorobenzenes with the (NHC)·AlH3 adducts 1, 3, and 5 and (Dipp2Im)·AliBu2H (7) showed the decisive influence of the reaction temperature on the H/F exchange and that 135 °C in xylene afforded the best product distribution. Although the HDF of hexafluorobenzene yielded 1,2,4,5-tetrafluorobenzene in moderate yields with traces of 1,2,3,4-tetrafluorobenzene and 1,2,4-trifluorobenzene, pentafluorobenzene was converted quantitatively into 1,2,4,5-tetrafluorobenzene, with (Dipp2Im)·AliBu2H (7) showing the highest activity and reaching complete conversion after 12 h at 135 °C in xylene. The HDF of hexafluoropropene with (Me2Im)·AlH3 (1) occurred even at low temperatures and preferably at the CF2 group with the formation of 1,2,3,3,3-pentafluoropropene (with 0.4 equiv. of 1) or 2,3,3,3-tetra-fluoropropene (with 0.9 equiv. of 1) as the main product.
Efficient preparation method of 2, 4, 5-trifluorophenylacetic acid
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Paragraph 0014, (2018/03/26)
The invention discloses an efficient preparation method of 2, 4, 5-trifluorophenylacetic acid and belongs to the technical field of synthesis of a pharmaceutical intermediate. The preparation method comprises synthesis of 2, 3, 5-trifluoroaniline, synthesis of 1, 2, 4-trifluorobenzene, synthesis of trifluorobromobenzene and synthesis of a desired product 2, 4, 5-trifluorophenylacetic acid. The preparation method is simple and easy to operate, utilizes cheap and easily available raw materials and has high reaction efficiency and good repeatability.
Base-Catalyzed Aryl-B(OH)2 Protodeboronation Revisited: From Concerted Proton Transfer to Liberation of a Transient Aryl Anion
Cox, Paul A.,Reid, Marc,Leach, Andrew G.,Campbell, Andrew D.,King, Edward J.,Lloyd-Jones, Guy C.
supporting information, p. 13156 - 13165 (2017/09/26)
Pioneering studies by Kuivila, published more than 50 years ago, suggested ipso protonation of the boronate as the mechanism for base-catalyzed protodeboronation of arylboronic acids. However, the study was limited to UV spectrophotometric analysis under acidic conditions, and the aqueous association constants (Ka) were estimated. By means of NMR, stopped-flow IR, and quenched-flow techniques, the kinetics of base-catalyzed protodeboronation of 30 different arylboronic acids has now been determined at pH > 13 in aqueous dioxane at 70 °C. Included in the study are all 20 isomers of C6HnF(5-n)B(OH)2 with half-lives spanning 9 orders of magnitude: a and Sδ values, kinetic isotope effects (2H, 10B, 13C), linear free-energy relationships, and density functional theory calculations, we have identified a mechanistic regime involving unimolecular heterolysis of the boronate competing with concerted ipso protonation/C-B cleavage. The relative Lewis acidities of arylboronic acids do not correlate with their protodeboronation rates, especially when ortho substituents are present. Notably, 3,5-dinitrophenylboronic acid is orders of magnitude more stable than tetra-and pentafluorophenylboronic acids but has a similar pKa.
Transition-Metal-Free Catalytic Hydrodefluorination of Polyfluoroarenes by Concerted Nucleophilic Aromatic Substitution with a Hydrosilicate
Kikushima, Kotaro,Grellier, Mary,Ohashi, Masato,Ogoshi, Sensuke
, p. 16191 - 16196 (2017/11/27)
A transition-metal-free catalytic hydrodefluorination (HDF) reaction of polyfluoroarenes is described. The reaction involves direct hydride transfer from a hydrosilicate as the key intermediate, which is generated from a hydrosilane and a fluoride salt. The eliminated fluoride regenerates the hydrosilicate to complete the catalytic cycle. Dispersion-corrected DFT calculations indicated that the HDF reaction proceeds through a concerted nucleophilic aromatic substitution (CSNAr) process.
