- Continuous flow reactor for Balz-Schiemann reaction: A new procedure for the preparation of aromatic fluorides
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A facile and highly efficient procedure for the preparation of aromatic fluorides by Balz-Schiemann reaction via two continuous flow reactors has been set up. The continuous diazotization reactor was run at about 25 °C with residence times of 10-20 s, and the continuous fluorodediazoniation reactor was performed with a residence time of 1 min in high yields. The reaction times can be greatly reduced by increasing temperature and thereby taking advantage of superior mass and heat transfer of a continuous flow system.
- Yu, Zhi-Qun,Lv, Yan-Wen,Yu, Chuan-Ming,Su, Wei-Ke
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Read Online
- Copper-Mediated Fluorination of Aryl Trisiloxanes with Nucleophilic Fluoride
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A method for the nucleophilic fluorination of heptamethyl aryl trisiloxanes to form fluoroarenes is reported. The reaction proceeds in the presence of Cu(OTf)2 and KHF2 as the fluoride source under mild conditions for a broad range of heptamethyltrisiloxyarenes with high functional group tolerance. The combination of this method with the silylation of aryl C?H bonds enables the regioselective fluorination of non-activated arenes controlled by steric effects following a two-step protocol.
- Dorel, Ruth,Boehm, Philip,Schwinger, Daniel P.,Hartwig, John F.
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supporting information
p. 1759 - 1762
(2020/02/05)
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- FLUORINATION OF ORGANIC COMPOUNDS
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Methods for fluorinating organic compounds are described herein.
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Page/Page column 24
(2012/11/06)
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- Deoxyfluorination of phenols
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An operationally simple ipso fluorination of phenols with a new deoxyfluorination reagent is presented.
- Tang, Pingping,Wang, Weike,Ritter, Tobias
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supporting information; experimental part
p. 11482 - 11484
(2011/10/02)
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- Halex reactions of aromatic compounds catalysed by 2-azaallenium, carbophosphazenium, aminophosphonium and diphosphazenium salts: A comparative study
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An increasing number of biologically active compounds in the pharma and agro-chemical sector contain carbon fluorine bonds. One of the most common methods to introduce fluorine into intermediates is the well-investigated halogen-exchange reaction, in which chloro- and bromoaromatics activated towards nucleophilic substitution, react with a fluoride source to yield the corresponding fluoroarenes. In general, the reaction is supported by phase-transfer catalysts. The use of a new class of very active phase-transfer catalysts gives the possibility of substituting even halogens with weak activation giving a convenient access to interesting compounds that are not available so far and opening up new synthetic routes in Halex chemistry. Our new classes of catalysts, CNC+ (1a), PNC+ (2a) and several different approaches presented by other groups are described and experimental results discussed.
- Pleschke, Axel,Marhold,Schneider,Kolomeitsev,R?schenthaler
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p. 1031 - 1038
(2007/10/03)
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- Preparation process of fluorine substituted aromatic compound
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A preparation process of a fluorine substituted aromatic compound comprising reacting an alkali metal or alkali earth metal salt of an aromatic compound having a hydroxy group with an organic fluorinating agent is disclosed. As a representative fluorinating agent, a bis-dialkylamino-difluoromethane compound, for example, 2,2′-difluoro-1,3-dimethylimidazolidine, is exemplified. According to the process, an industrially useful fluorinated aromatic compound, for example, a fluorobenzene, a fluorine substituted benzophenone, a fluorine substituted diarylsulfone can be prepared with ease in economy without specific equipment.
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- Rate Increase in Consecutive Nucleophilic Aromatic Substitution Reactions of Trichlorotrinitrobenzene: The Synthesis of 1-(Alkylamino)-3,5-dichloro-2,4,6-trinitrobenzenes
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The title compounds are formed by the nucleophilic aromatic substitution reaction between symtrichlorotrinitrobenzene and amines. The yields and relative rates of formation depend critically on the degree of alkylation of the nucleophile. Contrary to the usual behavior, the introduction of a second and third donor is facilitated in the case of ammonia and monoalkylamines, while this is not the case for secondary amines. This behavior is rationalized on the basis of intramolecular hydrogen bonding and substantiated by an X-ray analysis of 3,5-dichloro-2,4,6-trinitroaniline.
- Wolff, J. Jens,Zietsch, Andreas,Oeser, Thomas,Bolocan, Ion
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p. 5164 - 5168
(2007/10/03)
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- AROMATIC FLUORINE CHEMISTRY. PART 4. PREPARATION OF 2,6-DIFLUOROANILINE
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The preparation of 2,6-difluoroaniline from 1,3,5-trichlorobenzene is described. 1-Chloro-3,5-difluorobenzene prepared via KF exchange on 1,3,5-trichlorobenzene is dichlorinated and nitrated in a single reactor to a mixture of trichlorodifluoronitrobenzenes.The latter are reduced to ca. 4:1 mixture of 2,6-difluoroaniline and 2,4-difluoroaniline.
- Pews, R. G.,Gall, J. A.
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p. 307 - 316
(2007/10/02)
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