- Halogen-Exchange Fluorination of Primary Alkyl Halides Using 1B Metal Fluorides-Pyridine Derivatives
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Deep purplish red semicrystalline precipitates were obtained by the treatment of Cu2O with HF.After calcination at 100 deg C or higher temperature, this compound was successfully used as a highly effective halogen-exchange fluorination reagent for primary alkyl halides in the presence of pyridine derivatives.AgF and a mixture of CuF2 with copper powder also exhibited high activity in the reaction.
- Yoneda, Norihiko,Fukuhara, Tsuyoshi,Yamagishi, Ken,Suzuki, Akira
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Read Online
- LE FORMAMIDE, UN SUBSTITUT DE L'EAU XI : EFFET DU FORMAMIDE SUR LES REACTIONS D'ECHANGE CHLORE-FLUOR DANS LES CONDITIONS DE TRANSFERT DE PHASE LIQUIDE-SOLIDE
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The fluoride-chloride exchange reaction RCl + KF = RF + KCl catalysed by ammonium salts takes place in presence of formamide in place of water, faster and qith better yields.
- Escoula, B.,Rico, I.,Lattes, A.
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Read Online
- METHOD AND REAGENT FOR DEOXYFLUORINATION
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A safe, simple, and selective method and reagent for deoxyfluorination is disclosed. With the method and reagent disclosed herein, organic compounds such as carboxylic acids, carboxylates, carboxylic acid anhydrides, aldehydes, and alcohols can be fluorinated by using the most common nucleophilic fluorinating reagents and electron deficient fluoroarenes as mediators under mild conditions, giving corresponding fluoroorganic compounds in excellent yield with a wide range of functional group compatibility and easy product purification. For example, directly utilizing KF for deoxyfluorination of carboxylic acids provides the most economical and the safest pathway to access acyl fluorides, key intermediates for syntheses of peptide, amide, ester, and dry fluoride salts.
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Paragraph 0148-0150; 0152; 0167
(2021/05/29)
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- Fluorination reagent and deoxygenation fluorination method
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In order to overcome the problems of high cost and poor stability of the existing deoxidation fluorination reagent, the invention provides a fluorination reagent. The fluorination reagent comprises acation M and an anion, and the anion is selected from one or more of the following perfluoropolyether chain carboxylic acid anions: CF3 (OCF2) nCO2, and n is selected from 1-10. Meanwhile, the invention further discloses a deoxidation fluorination method. The fluorination reagent provided by the invention has the advantages that the materials are easy to obtain, the fluorination products can beobtained at higher yield for various alcohol substrates, and the universality for different alcohol substrates is better.
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Paragraph 0066-0116; 0127-0138; 0159-0160
(2020/12/30)
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- A Series of Deoxyfluorination Reagents Featuring OCF2Functional Groups
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Research on perfluoroalkyl ether carboxylic acids (PFECAs) as alternatives for perfluoroalkyl substances continues with the goal of protecting the environment. However, very little is known about the utilization of decomposition products of PFECAs. We report herein a new series of deoxyfluorination reagents featuring OCF2 functional groups derived from certain PFECAs. Alkyl fluorides were generated from various alcohols in ≤97% yield by these novel reagents. The mechanistic experiment verified in situ generation of carbonic difluoride (COF2).
- Cao, Wei,Chen, Qing-Yun,Guo, Yong,Su, Zhaoben,Wu, Chengying,Zhao, Shiyu
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supporting information
(2020/11/03)
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- Stabilization of Photocatalytically Active Uranyl Species in a Uranyl - Organic Framework for Heterogeneous Alkane Fluorination Driven by Visible Light
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When photoactivated, the uranyl ion is a powerful oxidant capable of abstracting hydrogen atoms from nonactivated C-H bonds. However, the highly reactive singly reduced [UVO2]+intermediate is unstable with respect to disproportionation to the uranyl dication and insoluble tetravalent uranium phases, which limits the usage of uranyl ions as robust photocatalysts. Herein, we demonstrate that photoactivated uranyl ions can be stabilized by immobilizing and separating them spatially in a uranyl-organic framework heterogeneous catalyst, NU-1301. The visible-light-photoactivated uranyl ions in NU-1301 exhibited longer-lived U(V) and radicals than those in homogeneous counterparts, as evidenced by X-ray photoelectron spectroscopy and time-dependent electron paramagnetic resonance, leading to higher turnovers and enhanced stability for the fluorination of nonactivated alkanes.
- Zhang, Xuan,Li, Peng,Krzyaniak, Matthew,Knapp, Julia,Wasielewski, Michael R.,Farha, Omar K.
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supporting information
(2020/07/03)
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- Photochemical activation of SF6 by N-heterocyclic carbenes to provide a deoxyfluorinating reagent
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The activation of the greenhouse gas SF6 using electron-rich N-heterocyclic carbenes gave 2,2-difluoroimidazolines or 2,2-difluoroimidazolidines as well as 2-thio derivatives of the carbene precursors. The N-heterocyclic carbenes can also convert SF4 to give similar products. The difluoroimidazolidine derivatives were applied in deoxyfluorination reactions. Furthermore, the activation of SF6 and the fluorination can be coupled in a one-pot process to convert 1-octanol into 1-fluorooctane.
- Tomar, Pooja,Braun, Thomas,Kemnitz, Erhard
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supporting information
p. 9753 - 9756
(2018/09/10)
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- ORGANIC SYNTHESIS APPLICATIONS OF NON-AQUEOUS FLUORIDE SALT SOLUTIONS
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Processes and reaction mixtures including non-aqueous solvent mixtures are presented. Non-aqueous solvent mixtures including fluoride salt and non-aqueous solvent combinations are provided that possess high fluoride ion concentrations useful for a range of applications, including organic synthesis. Further non-aqueous solvent mixtures are provided including a salt possessing a non-fluoride anion and a non-aqueous solvent that, when contacted with aqueous fluoride-containing reagents, extract fluoride ions to form non-aqueous fluoride-ion solutions possessing high fluoride-ion concentrations. The salts include an organic cation that does not possess a carbon in the β-position or does not possess a carbon in the β-position having a bound hydrogen. This salt structure facilitates its ability to be made anhydrous without decomposition. Example anhydrous fluoride salts include (2,2-dimethylpropyl)trimethylammonium fluoride and bis(2,2-dimethylpropyl)dimethylammonium fluoride. The combination of these fluoride salts with at least one fluorine-containing non-aqueous solvent (e.g., bis(2,2,2-trifluoroethyl)ether; (BTFE)) promotes solubility of the salt within the non-aqueous solvents.
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Paragraph 0178-0181
(2017/03/21)
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- Solvent free nucleophilic introduction of fluorine with [bmim][F]
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1-n-Butyl-3-methylimidazolium fluoride ([bmim][F]) proved very efficient fluorinated reagent for nucleophilic substitution over sulfonate esters and alkyl halides. Preparation of the ionic liquid as well as its use as the reagent has been performed to be the more eco-friendly as possible. No organic solvent is needed for the fluoride introduction, reaction times are reduced by using microwave as the heating source, and the ionic liquids carefully recycled. Furthermore, no special care has to be taken as the presence of water in [bmim][F] was not deleterious to the transformation yield.
- Bouvet, Sébastien,Pégot, Bruce,Marrot, Jérome,Magnier, Emmanuel
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p. 826 - 829
(2014/02/14)
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- Silver-catalyzed radical fluorination of alkylboronates in aqueous solution
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We report herein an efficient and general method for the deboronofluorination of alkylboronates. Thus, with the catalysis of AgNO3, the reactions of various alkylboronic acids or their pinacol esters with Selectfluor reagent in acidic aqueous solution afforded the corresponding alkyl fluorides under mild conditions. A broad substrate scope and wide functional group compatibility were observed. A radical mechanism is proposed for this site-specific fluorination.
- Li, Zhaodong,Wang, Zhentao,Zhu, Lin,Tan, Xinqiang,Li, Chaozhong
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p. 16439 - 16443
(2015/01/09)
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- Efficient SN2 fluorination of primary and secondary alkyl bromides by copper(I) fluoride complexes
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Copper(I) fluoride complexes ligated by phenanthroline derivatives have been synthesized and structurally characterized by X-ray crystallography. These complexes adopt as either ionic or neutral forms in the solid state, depending on the steric bulkiness of the substituent groups on the phenanthroline ligands. These complexes react with primary and secondary alkyl bromides to produce the corresponding alkyl fluorides in modest to good yields. This new method is compatible with a variety of important functional groups such as ether, thioether, amide, nitrile, methoxyl, hydroxyl, ketone, ester, and heterocycle moieties.
- Liu, Yanpin,Chen, Chaohuang,Li, Huaifeng,Huang, Kuo-Wei,Tan, Jianwei,Weng, Zhiqiang
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p. 6587 - 6592
(2013/12/04)
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- Nucleophilic fluorination reactions starting from aqueous fluoride ion solutions
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The sulfonium borane 2+ reacts with fluoride anions in MeOH/H2O mixtures to afford the zwitterionic fluoroborate 2-F as an easily isolable nonhygroscopic solid. In dry acetonitrile, 2-F reacts with PhS- to afford the anionic fluoroborate 1-F-. The latter is very labile and acts as a nucleophilic fluorination reagent toward a variety of substrates including alkylhalides and electron-deficient aromatic compounds. This approach may become broadly applicable to nucleophilic fluorination procedures that involve wet fluoride sources.
- Zhao, Haiyan,Gabbai, Francois P.
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supporting information; experimental part
p. 1444 - 1446
(2011/05/08)
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- Homogeneous nucleophilic radiofluorination and fluorination with phosphazene hydrofluorides
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A series of phosphazenium hydrofluorides, P1 tBu·[18/19F]HF, P1 tOct·[18/19F]HF, P2Et· [18/19F]HF, and P4tBu·[ 18/19F]HF, was synthesized. The radioactive phosphazenium [ 18F]hydrofluorides were obtained by the one-step formation and trapping of gaseous [18F]HF with the respective phosphazene bases. The [19F] isotopomers were prepared from the corresponding phosphazene bases and Et3N·3HF. Under the design of experiment (DoE)-optimized conditions, P2Et·HF and P 4tBu·HF fluorinated alkyl chlorides, bromides, and pseudohalides in 76-98 % yield, but gave lower yields with iodides and electron-deficient arenes. DoE models showed that fluorination can be performed in glass vessels, and that the reactivity of P2Et· HF and P4tBu·HF is dominated by solvent polarity but is insensitive to water to at least 2 equiv. In contrast, P1 tBu·HF and P1tOct·HF were unstable towards autofluorolysis. DFT calculations were performed to rationalize this finding in terms of diminished steric bulk, higher Parr's electrophilicity, and chemical hardness of P1RH +. The corresponding radiofluorination reaction gave no valid DoE model but displayed similar substrate scope. High specific activity and excellent radiochemical yields with various pseudohalides (81-91 %) suggest that the proposed radiofluorination methodology can complement the current [ 18F]KF/Kryptofix methods, particularly in the areas for which nonpolar reaction conditions are required. A tale of fluoride: Up to 82 % of [18F]fluoride can be recovered from aqueous solution as [ 18F]HF gas in just one step (see scheme; Tf: trifluoromethanesulfonyl, Ms: methanesulfonyl, Ts=p-toluenesulfonyl). Trapped as phosphazenium hydrofluorides, 18F- and 19F- isotopomers attain high nucleophilicity and solubility in nonpolar solvents. Excelling in fluorination and radiofluorination of various pseudohalides, their substrate scope also extends to halides and nitroarenes. Copyright
- Mathiessen, Bente,Jensen, Andreas T. I.,Zhuravlev, Fedor
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scheme or table
p. 7796 - 7805
(2011/08/22)
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- Ionic liquids as recyclable solvents for diethylaminosulfur trifluoride (DAST) mediated fluorination of alcohols and carbonyl compounds
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The first simple and efficient method for the synthesis of mono and gem-difluorinated molecules using [C8mim][PF6] ionic liquid as a recyclable solvent medium with diethylaminosulfur trifluoride (DAST) as the fluorinating reagent, is reported.
- Das, Saibal,Chandrasekhar, Srivari,Yadav, Jhillu Singh,Grée, René
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p. 5305 - 5307
(2008/02/10)
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- 1,1,3,3,3-Pentafluoropropene secondary amine adducts new selective fluorinating agents
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Addition of secondary amine SA (dimethylamine DMA, diethylamine DEA, pyrrolidine Pyr, piperidine Pip, morpholine Mor) to pentafluoropropene PFP gives rise to generation of mixtures of two products (1-dialkylamine-1,3,3,3-tetrafluoropropene and N,N-dialkyl-1,1,3,3,3-pentafluoropropylamine) in different ratios. Those reaction mixtures, however, were found to be efficient fluorinating agents replacing hydroxyl groups in alcohols into fluorine. In general, they react with alcohols yielding corresponding fluorides, equimolar amounts of appropriate 3,3,3-trifluoropropionamide and hydrogen fluoride. Aliphatic primary alcohols including octanol and benzylic alcohol yield only alkyl fluorides. The secondary and tertiary alcohols, beside the desired fluorides, give usually considerably amount of alkenes.
- Koroniak, Henryk,Walkowiak, Justyna,Grys, Krzysztof,Rajchel, Andrzej,Alty, Adam,Du Boisson, Rick
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p. 1245 - 1251
(2008/09/20)
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- Anhydrous flouride salts and reagents and methods for their production
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Anhydrous organic fluoride salts and reagents prepared by a method comprising the nucleophilic substitution of a fluorinated aromatic or fluorinated unsaturated organic compound with a salt having the formula: [QnM]x+Ax?in an inert polar, aprotic solvent; wherein M is an atom capable of supporting a formal positive charge, the n groups Q are independently varied organic moieties, n is an integer such that the [QnM] carries at least one formal positive charge, x is an integer defining the number of formal positive charge(s), +, carried by the [QnM], A? is an anionic nucleophile capable of substituting for F in the fluorinated compound and F represents fluorine or a radioisotope thereof.
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Page/Page column 3-5
(2008/06/13)
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- FLUORINATING AGENT AND METHOD FOR PRODUCING FLUORINE-CONTAINING COMPOUND USING SAME
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A method for producing a fluorine-containing organic compound represented by the formula (7): ????????R-Fm?????(7) wherein R represents a substituted or unsubstituted saturated hydrocarbon group, or a substituted or unsubstituted aromatic group and m represents an integer satisfying the inequality: 1≦m≦n, which comprises reacting a fluorinating agent represented by the formula (1): wherein R1 and R3 are the same or different, and represent an optionally substituted alkyl group, R2, R4 and R5 are the same or different, and represent a hydrogen atom or an optionally substituted alkyl group, x satisfies 0- represents a monovalent anion other than a fluoride ion, with an organic compound of the formula (6): ????????R-Ln?????(6) wherein R is the same as defined above, L represents a leaving group and n represents an integer of 1 or more, and a fluorinating agent using the same are described.
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Page/Page column 13-14
(2008/06/13)
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- FLUORINATION IN LIQUID CARBON DIOXIDE
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A method of fluorinating a substance comprises providing a reaction mixture comprising a liquid or supercritical carbon dioxide reaction medium, a first reactant, and a second reactant, wherein the first reactant is a fluorinating reagent, and then contacting the first reactant and the second reactant in the carbon dioxide such that the first reactant fluorinates the second reactant.
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Page/Page column 5-6
(2008/06/13)
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- New fluoride ion reagent from pentafluoropyridine
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A new nucleophilic fluorinating agent, derived from reaction of dimethylaminopyridine (DMAP) with pentafluoropyridine, has been synthesised and assessed in various carbon-fluorine bond forming processes.
- Murray, Christopher B.,Sandford, Graham,Korn, Stewart R.,Yufit, Dmitrii S.,Howard, Judith A.K.
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p. 571 - 576
(2007/10/03)
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- Anhydrous tetrabutylammonium fluoride
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Tetrabutylammonium fluoride (TBAF) is prepared at low temperature by nucleophilic aromatic substitution of hexafluorobenzene with tetrabutylammonium cyanide. Adventitious water is scavenged during this synthesis by the generated hexacyanobenzene, which readily adds water under basic conditions. Contrary to expectations, TBAF is stable to Hofmann elimination in polar aprotic solvents under anhydrous conditions. Added hydroxylic solvents are shown to catalyze the decomposition of TBAF and to catalyze proton exchange with DMSO. The synthetic utility of this salt is described briefly. Copyright
- Sun, Haoran,DiMagno, Stephen G.
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p. 2050 - 2051
(2007/10/03)
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- Cocatalysis in phase-transfer catalyzed fluorination of alkyl halides and sulfonates
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Phase-transfer catalyzed (PTC) fluorination of alkyl halides and sulfonates with solid KF proceeds efficiently when cocatalyst triphenyltin fluoride is used. The cocatalytic action of the tin compound consists in continuous formation of difluorotriphenylstannate anion that as the tetraalkyloammonium salt enter the solution where it reacts with alkyl halides to produce alkyl fluorides. The cocatalytic system was used to synthesis of 1,1-difluoroalkanes in two steps from aldehydes. A new kind of PTC was elaborated in which Ph 3SnF acts as phase transfer catalyst via continuous formation of potassium salts of diflurotriphenylstannate anions soluble in dipolar aprotic solvents. A new, simple and general method of synthesis of tetraalkylammonium and potassium salts of difluorotriorgano-tin, silicon and germanium anions is reported.
- Ma?kosza,Bujok
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p. 209 - 216
(2007/10/03)
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- Fluorine compound and fluorinating agent comprising the compound
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A fluorine compound represented by Formula (1) is provided. The above fluorine compound is effective for introducing a fluorine atom into a compound having an active group such as an oxygen-containing functional group, and it can be used for uses of surface treatment, cleaning and coating. Further, after the fluorination reaction, the above compound is recovered and can be reused as a starting material for producing the above fluorine compound, and it is useful for various fluorination processes. (wherein X represents a nitrogen or phosphorus atom; R0, R1, and R2 represent hydrogen, an alkyl group or aryl group which may have a substituent, and they each may be the same or different; and R0, R1, and R2 may be combined with each other to form a ring).
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- A new type of phase-transfer catalysis via continuous transfer of fluoride anions to the organic phase in the form of potassium difluorotriphenylstannate
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Fluorination of alkyl halides and sulfonates is efficiently executed in a liquid-solid phase-transfer catalysis system with Ph3SnF as phase-transfer catalyst acting via continuous formation of lipophilic Ph 3SnF2 anions entering the organic phase in the form of the potassium salt.
- Ma?kosza, Mieczys?aw,Bujok, Robert
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p. 1385 - 1386
(2007/10/03)
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- Ionic liquids as media for nucleophilic flurination
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The use of Room Temperature Ionic Liquids (RTILs) for a variety of halogen exchange (Halex) fluorination processes using alkali metal fluorides is assessed. Whilst fluorination of a range of halogenated substrates is possible in good yield, the utility of RTILs as reusable, inert media for such reactions is limited by the gradual decomposition of the RTIL in the presence of highly basic fluoride ion.
- Murray, Christopher B.,Sandford, Graham,Korn, Stewart R.
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- 2,2-Difluoro-1,3-dimethylimidazolidine (DFI). A new fluorinating agent
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2,2-Difluoro-1,3-dimethylimidazolidine (DFI) is a new deoxo-fluorinating agent that is useful for the conversion of alcohols to monofluorides, and aldehydes/ketones to gem-difluorides under mild conditions.
- Hayashi, Hidetoshi,Sonoda, Hiroshi,Fukumura, Kouki,Nagata, Teruyuki
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p. 1618 - 1619
(2007/10/03)
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- A useful conversion of alcohols to alkyl fluorides
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A useful conversion of alcohols to alkyl fluorides via their fluoroformates is introduced. The fluoroformates are obtained in nearly quantitative yield from the alcohols by treatment with COF2 (generated in situ from bis(trichloromethyl) carbonate) in ether with KF as an added acid scavenger. The neat fluoroformates are cleaved to the fluorides by heating at 120-125°C using hexabutylguanidinium fluoride (HBGF) as the catalyst.
- Flosser, David A,Olofson, Roy A
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p. 4275 - 4279
(2007/10/03)
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- Tetrabutylammonium butyldifluorodimethylsilicate and difluorodimethylphenylsilicate, new nucleophilic fluorinating reagents
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Tetrabutylammonium butyldifluorodimethylsilicate (TAMBS, 1a) and tetrabutylammonium difluorodimethylphenylsilicate (TAMPS, 1b) were conveniently prepared from the corresponding substituted fluorodimethylsilanes and tetrabutylammonium fluoride. Both fluorosilicates 1a, 1b are powerful nucleophilic fluorinating reagents which transform primary or secondary halides, tosylates, or mesylates to the corresponding fluorides in moderate to good yields.
- Kví?ala,Mysík,Paleta
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p. 547 - 549
(2007/10/03)
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- Nitrogen-based halogenating agents and process for preparing halogen-containing compounds
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Disclosed are a fluorinating agent represented by the general formula (1): wherein R1to R4are a substituted or unsubstituted, saturated or unsaturated alkyl group or a substituted or unsubstituted aryl group, and can be the same or different; R1and R2or R3and R4can bond to form a ring including a nitrogen atom or a nitrogen atom and other hetero atoms; or R1and R3can bond to form a ring including a nitrogen atom or a nitrogen atom and other hetero atoms, for example: a preparation process of the fluorinating agent and a process for preparing fluorine compounds by reacting various compounds with the fluorinating agent. The invention has also disclosed that the fluorinating agent is very effective for fluorinating oxygen containing functional compounds.
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- A facile new method for the two-step substitution of hydroxy groups in primary alcohols for trifluoromethyl and pentafluoroethyl moieties
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In an efficient procedure the nucleophilic trifluoromethylation and pentafluoroethylation of alkyl triflates using (trifluoromethyl)- and (pentafluoroethyl)trimethylsilane in the presence of anhydrous tetramethylammonium fluoride is achieved giving 71-80% isolated yields.
- Sevenard,Kirsch,R?schenthaler,Movchun,Kolomeitsev
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p. 379 - 381
(2007/10/03)
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- Activation of tetrabutylammonium hydrogen difluoride with pyridine: A mild and efficient procedure for nucleophilic fluorination
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The nucleophilic fluorination of alkyl iodides, bromides and tosylates and of α-bromo- or α-chloroketones is smoothly effected by tetrabutylammonium hydrogen difluoride in the presence of pyridine, in dioxane or THF, with good or satisfying substitution-to-elimination ratio.
- Moughamir, Khadija,Atmani, Aziz,Mestdagh, Helene,Rolando, Christian,Francesch, Charlette
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p. 7305 - 7306
(2007/10/03)
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- New method of preparation of fluoro compounds via utilisation of ammonium and phosphonium perfluorocyclobutane ylides as fluorination reagents
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Ammonium- and phosphoniumperfluorocyclobutane ylides (7-11), easily prepared from perfluorocyclobutene (1) and tertiary amines (2-4) or phosphines (5,6), smoothly react with primary or secondary alcohols (12-18) and carboxylic acids (19, 20) with formation of alkyl fluorides (21-26) or acyl fluorides (27, 28), respectively. A mechanism for the reaction is proposed.
- Pasenok, Sergej V.,De Roos, Marijn E.,Appel, Wolfgang K.
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p. 2977 - 2982
(2007/10/03)
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- A facile synthesis of organofluorine compounds using a semi-molten mixture of tetrabutylammonium bromide and an alkali metal fluoride
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A semi-molten mixture of tetrabutylammonium bromide and an alkali metal fluoride (KF or CsF) has been found to be an efficient reagent system for the preparation of organofluorine compounds, e.g., CH3(CH2)7F, CH2=CH-CH2F, FCH2CO2C2H5, C6H5COF, and related compounds through facile fluoride-ion exchange with organohalides.The system provides a simple and convenient alternative to 'anhydrous' tetrabutylammonium fluoride for the synthesis of organofluorine compounds. - Keywords: Semi-molten mixture; Tetrabutylammonium bromide; Alkali metal fluorides; Organofluorine compounds; NMR spectroscopy
- Bhadury, Pinaki S.,Pandey, Mamta,Jaiswal, Devendra K.
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p. 185 - 188
(2007/10/02)
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- Le formamide, un substitut de l'eau dans les reactions d'echange chlore-fluor par transfert de phase solide-liquide
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The fluoride-chloride exchange reaction RCl+KF -> RF+KCl catalysed by ammonium salts, was found to take place in presence of formamide in place of water.The results, depending of RCl are discussed in this paper.
- Escoula, Brigitte,Rico, Isabelle,Lattes, Armand
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p. 256 - 259
(2007/10/02)
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- Process for the preparaiton of alkyl fluorides
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Preparation of alkyl fluoride by replacement of an aliphatic hydroxy group with fluorine. The reaction is performed by treating a sulfonyl derivative of an aliphatic hydroxy group with an inorganic fluoride in a polyglycol.
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- Dramatic Effect of the Specific Solvation on the Reactivity of Quaternary Ammonium Fluorides and Poly(hydrogen fluorides), (HF)n*F-, in Media of Low Polarity
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A quantitative study of how the intrinsic reactivity (nucleophilicity and basicity) of the fluoride anion of hexyl4N+F- is affected in solvents of low polarity by the specific solvation of a limited number of water molecules has been performed.The nucleophilicity enhancement is extrapolated to be about 3 orders of magnitude by reducing the specific hydration n of the anion from 8.5 to 0.Such enhancement is much higher (ca100 times) than that obtained, under the same conditions, by dehydrating the other halides.The nucleophilicity scale of anhydrous anions found,F- >> Cl- > Br- > I-, reflects those well-known in dipolar aprotic solvents and in the gas phase.Comparison in the same hydration range shows that the basicity of the fluoride anion is much more affected by specific solvation than is its nucleophilicity.Extension of this study to quaternary ammonium poly(hydrogen fluorides) Q+(HF)n*F-, where n = 1, 2, provides the following reactivity scale: F- >> HF2- > H2F3-.The increasing stabilization of F- anion, by interaction with hydrogen fluoride in the sequence F- - -, accounts for the much lower reactivity observed in the case of poly(hydrogen fluorides) with respect to that of the hypothetical anhydrous fluoride (F- : HF2- : H2F3- = 8.5*105 : 1.2*102 : 1).This also explains the different sensitivity of these anions to the specific hydration which decreases in the same order: F- >> HF2- > H2F3-.
- Landini, Dario,Maia, Angelamaria,Rampoldi, Alessandro
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p. 328 - 332
(2007/10/02)
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- Silver Fluoride Supported on Calcium Fluoride. Improved Fluorination and Halofluorination Reactions
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Silver fluoride dispersed on the surface of calcium fluoride shows improved fluoride nucleophilicity for halogen exchange and addition to alkenes.
- Ando, Takashi,Cork, David G.,Fujita, Mitsue,Kimura, Takahide,Tatsuno, Toshio
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p. 1877 - 1878
(2007/10/02)
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- EASY AND EFFICIENT HETEROGENEOUS NUCLEOPHILIC FLUORINATION WITHOUT SOLVENT
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In the absence of solvent, either or were found to be effective and practical reagents for the fluorination of several organic halides under mild conditions.
- Bram, Georges,Loupy, Andre,Pigeon, Philippe
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p. 1661 - 1668
(2007/10/02)
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- LE FORMAMIDE, UN SUBSTITUT DE L'EAU XVI 1: REACTIONS D'ECHANGE CHLORE-FLUOR EN TRANSFERT DE PHASE SOLIDE-LIQUIDE
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The chloride-fluoride exchange reaction, RCl+KF -> RF+KCl, catalised by ammonium salts, was found to take place in the presence of formamide when this is used as a replacement for water.The experimental results and their dependence on RCl are discussed in this communication.
- Escoula, B.,Rico, I.,Lattes, A.
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p. 487 - 494
(2007/10/02)
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- Use of Polyethylene Glycol in the Synthesis of Alkyl Fluorides from Alkyl Sulfonates
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In the synthesis of monofluorinated organic compounds, the reaction of potassium fluoride with mesylates and tosylates of alcohols affords fluoro derivatives when polyethylene glycol 400 is used as solvent and catalyst.The limitation of this reaction is the solvolysis of the leaving group by the solvent; the phenomenon is controlled by the degree of steric hindrance around the reaction centre.
- Badone, Domenico,Jommi, Giancarlo,Pagliarin, Roberto,Tavecchia, Paolo
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p. 920 - 921
(2007/10/02)
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- A Facile Method for the Fluorine Substitution of Phenylthio Group via Sulfonium Salts Using Cesium Fluoride
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Monofluorinated compounds are easily prepared in good yields by treating phenyl sulfides with methyl fluorosulfonate and cesium fluoride in refluxing dichloromethane, successively.This reaction proceeds under so mild conditions as not to affect the coexisting bromine substituent.
- Ichikawa, Junji,Sugimoto, Ken-ichi,Sonoda, Takaaki,Kobayashi, Hiroshi
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p. 1985 - 1988
(2007/10/02)
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- The Combination of Potassium Fluoride and Calcium Fluoride: A Useful Heterogeneous Fluorinating Reagent
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The combination of potassium fluoride and calcium fluoride was found to be an effective and practical solid reagent for the fluorination of various organic chlorides and bromides under mild conditions.
- Ichihara, Junko,Matsuo, Toshiya,Hanafusa, Terukiyo,Ando, Takashi
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p. 793 - 794
(2007/10/02)
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- FLUORINATION BY USE OF TRANSITION METAL FLUORIDE-BIPYRIDINE COMPLEX IN APROTIC ORGANIC SOLVENTS
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Bipyridine complexes of transition metal fluorides which are soluble in aprotic organic sovents are used for the fluorination of organic halides under mild conditons.
- Sonoda, Hirosi,Sonoda, Takaaki,Kobayashi, Hiroshi
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p. 233 - 236
(2007/10/02)
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- Effect of Water on the Extraction and Reactions of Fluoride Anion by Quaternary Ammonium Phase-Transfer Catalysts
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The maximum conversion of the fluoride-chloride exchange reaction RCl + KF -> RF + KCl catalyzed by quaternary onium salts was found to be strongly dependent on the water content of the inorganic salt.A maximum conversion was obtained when the potassium fluoride contained 0.33 mol of water per mol of KF.This phenomenon is due to better extraction of the fluoride anion when the KF is drier, offset by decomposition of the catalyst in the absence of water.It was shown that the selectivity constant KselCl/F is dependent on composition of the inorganic salt and on temperature.Rate measurements indicate that the mechanism proposed by Starks for liquid-liquid exchange reactions is valid also in a solid-liquid process which is also chemically controlled.
- Dermeik, Salman,Sasson, Yoel
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p. 879 - 882
(2007/10/02)
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- The efficiency of diphenylalkylsulfonium salts as alkylating agents
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A series of the title reagents have been used for the alkylation of a number of nucleophiles including iodide, cyanide, thiocyanate and fluoride ions as well as ethyl acetoacetate, phenylacetonitrile and a variety of nitrogen heterocyclic compounds.The results compared favorably with literature methods.
- Badet, Bernard,Julia, Marc,Lefebvre, Christian
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p. 431 - 434
(2007/10/02)
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- DARSTELLUNG VON PRIMAEREN ALKYLFLUORIDEN UNTER EINSATZ DER PHASEN TRANSFER KATALYSE
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The influence of the following factors on the solid-liquid PTC fluorination reaction of primary alkyl halides was studied: the catalyst quantity applied, the water content of solid alkali fluoride salt, and the type of catalyst.Kinetic curves at different temperatures were found for the reaction.The maximum yield is a function of the interaction of two parallel running reactions, namely the direct fluorination reaction and the catalyst decomposition.
- Dermiek, Salman,Sasson, Yoel
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p. 431 - 438
(2007/10/02)
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- HALOGEN REDISTRIBUTION REACTIONS BETWEEN ALKYL HALIDES AND TRIMETHYLSILYL IODIDE
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Trimethylsilyl iodide has been found to react rapidly at 50 deg C with 1-fluorooctane, 2-fluorooctane and benzyl fluoride to produce the corresponding octyl or benzyl iodides and trimethylsilyl fluoride.Also, it reacts rapidly and cleanly with t-butyl chloride or bromide to form t-butyl iodide.However, it does not react readily with the 1-octyl, 2-octyl, benzyl or allyl chlorides or bromides.We have discovered that tetra-n-butylammonium iodide catalyzes the reactions of primary alkyl chlorides or bromides with trimethylsilyl iodide, and molecular iodine catalyzes the reactions of secondary and tertiary alkyl chlorides and bromides.However, tetra-n-butylammonium iodide slows down the reactions of secondary and tertiary alkyl chlorides and bromides.Mechanistic pathways are suggested for each of the various types of halogen redistribution processes encountered.
- Friedrich, Edwin C.,Lucca, George de
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p. 143 - 148
(2007/10/02)
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