共查询到20条相似文献,搜索用时 15 毫秒
1.
Recent studies on electrochemical partial fluorination in ionic liquid fluoride salts are reviewed. At first, historical background and some problems of electrochemical fluorination in organic solvents are briefly mentioned. Solvent-free electrochemical fluorinations in ionic liquids are explained as follows. Ultrasonication was found to improve both the yield and current efficiency for electrochemical fluorination of α-phenylthioacetate, which is mainly attributable to marked mass transport promotion of the substrate and the suppression of anode passivation. Highly regioselective and efficient fluorination of cyclic ethers, lactones, and cyclic carbonate was achieved in Et4NF·4HF and Et3N·5HF. Selective fluorination of hardly oxidizable phthalide was realized using a combination of imidazolium and fluoride ionic liquids. The unique effect of imidazolium ionic liquids on electrochemical fluorodesulfurization of 3-phenylthiophthalide was explained. Reuse of ionic liquids for electrochemical fluorination is also possible. 相似文献
2.
Shinsuke Inagi Takahiro Sawamura Toshio Fuchigami 《Electrochemistry communications》2008,10(8):1158-1160
Anodic fluorination of ethyl α-(2-pyrimidylthio)acetate in neat ionic liquid hydrogen fluoride salts (Et3N–3HF, Et4NF–4HF, Et4NF–5HF) was investigated to avoid an anode passivation, which sometimes occurs during anodic fluorination in organic solvent. In order to improve the yield of fluorinated product, polyether having coordination ability to cation and anodic stability was introduced to the reaction system as additives (3%). Furthermore, such additives were found to be also effective for anodic fluorodesulfurization of 4-phenylthio-1,3-dioxolan-2-one in neat ionic liquid system. 相似文献
3.
This article provides an outline of recent studies on selective electrochemical fluorination in ionic liquid fluoride salts toward green sustainable chemistry. First, a brief historical background of electrochemical fluorination in organic solvents is provided, and some particular problems and unique solvent effects associated with this technique are briefly mentioned. Second, recent progress in selective fluorination and fluorodesulfurization of organic molecules and macromolecules in ionic liquids using direct and indirect electrolysis with recyclable mediators is reviewed. 相似文献
4.
Michael Berger Marola S. Lenhard Prof. Dr. Siegfried R. Waldvogel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(41):e202201029
The para-selective fluorination reaction of anilides using electrochemically generated hypervalent ArIF2 is reported, with Et3N ⋅ 5HF serving as fluoride source and as supporting electrolyte. This electrochemical reaction is characterized by a simple set-up, easy scalability and affords a broad variety of fluorinated anilides from easily accessible anilides in good yields up to 86 %. 相似文献
5.
N. Ilayaraja 《Journal of fluorine chemistry》2008,129(3):185-192
Selective electrochemical fluorination of alkyl phenylacetates (Ph-CH2-COOR, where R is methyl, ethyl, n-propyl, n-butyl, i-propyl and sec-butyl) under galvanostatic conditions were reported in Et3N·4HF medium. Preparative electrolysis experiments were carried out both in pre-electrolysed dry Et3N·4HF and the same electrolyte medium without pre-electrolysis. Very little hydrolysed fluorinated products were obtained in pre-electrolysed medium where as significant quantities of hydrolysed products leading to fluorinated phenylacetic acid were obtained from Et3N·4HF without pre-electrolysis. Under optimum experimental conditions up to 87% selectivity of monofluoro ester could be achieved. Difluoro alkyl phenylacetate, monofluoro and difluoro phenylacetic acids were the other predominant side products obtained. The hydrolysis appears to be initiated by tautomeric transformation of proton after the initial electro oxidative formation of the cation radical. 19F as well as 1H NMR spectroscopy have been employed to identify the minor constituents formed during the electro oxidative process. 相似文献
6.
Regioselective anodic monofluorination of 4-oxo-2-pyrimidyl sulfides was investigated under various electrolytic conditions. Anodic fluorination was successfully carried out using Et(4)NF.4HF in dimethoxyethane (DME) to provide the corresponding alpha-fluorinated products in good yields. In contrast, acetonitrile (MeCN) was not suitable for the anodic fluorination due to the severe anode passivation during the electrolysis. A mixed solvent of DME and MeCN was found to be also effective for the fluorination, and the product yield increased with an increase of the ratio of DME to MeCN. The superiority of DME can be explained mainly in terms of the suppression of the anode passivation and enhancement of the nucleophilicity of the fluoride ions. Such marked solvent effects on the anodic fluorination were discussed in detail. 相似文献
7.
Bin Yin 《Tetrahedron》2010,66(34):6820-10631
Anodic fluorination of various N-acetyl-3-substituted indole derivatives was successfully carried out in Et4NF-4HF/MeCN to provide the corresponding trans-2,3-difluoro-2,3-dihydroindoles exclusively or selectively. Treatment of difluorinated products with a base provided monofluoroindole derivatives or monofluoroindoline derivative depending on the substituents at the 3-position. 相似文献
8.
Hydrogen fluoride is a basic fluorinating reagent, but handling it is difficult. For this reason, some modified fluorinating reagents such as HF-pyridine, Et3N-HF, and poly(hydrogen fluoride) complex have been developed. Those reagents, however, still require aqueous work-up procedures which generate hydrogen fluoride. Recently, ionic liquids have received much attention because of the ease in handling them and the possibility of non-aqueous work-up. An ionic liquid, 3-ethyl-1-methyimidazolium oligo hydrogen fluoride (EMIMF(HF)2.3), which is stable in air and moisture, can be used as a hydrogen fluoride equivalent for some fluorination reactions; it does not require an aqueous work-up. 相似文献
9.
A. O. Terent’ev M. M. Platonov I. B. Krylov G. I. Nikishin 《Russian Chemical Bulletin》2009,58(2):335-338
Iodine-catalyzed reactions of bis(1-hydroperoxycycloalkyl) peroxides with ketals give, via replacement of two alkoxy groups, the cyclic peroxides, 1,2,4,5,7,8-hexaoxonanes, in up to 82% yields. The cyclization is
very sensitive to the solvent nature. Among MeCN, Et2O, THF, CHCl3, CH2Cl2, hexane, and MeOH, the best results were achieved with the first three solvents. 相似文献
10.
Vera Yu. Petukhova Leonid L. Fershtat Vadim V. Kachala Vladimir V. Kuznetsov Dmitriy V. Khakimov Tatyana S. Pivina Nina N. Makhova 《Journal of heterocyclic chemistry》2013,50(2):326-336
An interaction of 1,2‐dialkyldiaziridine and 1,2,3‐trialkyldiaziridine with methyl propiolate was studied both in organic solvent (MeCN, CH2Cl2, C6H6) and in ionic liquids. Earlier unknown linear structures, in which three molecules of methyl propiolate were suited to one diaziridine molecule (adducts 1 : 3), were obtained in MeCN. The diaziridine ring expansion products 1,2,3,4‐tetrahydropyrimidine derivatives (adducts 1 : 2) and, along with them in some cases, the same linear structures were obtained in ionic liquids. A mechanism of reactions found was offered. The regioselectivity of reactions was supposed to determine by the structure of substituents in initial diaziridines. This conclusion was supported by quantum chemical calculations. 相似文献
11.
Electrochemical fluorination (Simons process) provides a cheap commercial access to a series of tris(perfluoroalkyl)diflurophosphoranes. These substances are convenient starting material for the preparation of various fluoro-chemicals. The synthesis of new conducting salts and ionic liquids with perfluoroalkyl-fluorophosphate (FAP) and perfluoroalkyl-phosphinate anions is described. FAP ionic liquids exhibit excellent hydrolytic stability, low viscosity and high electrochemical and thermal stability. Organic and inorganic salts with FAP anions possess high electrochemical stability and conductivity that makes them attractive for application in several electrochemical devices (Li-ion batteries, super-capacitors, etc.). The possible application of H[(RF)3PF3] (HFAP), (RF)2P(O)(OH) and (RF)P(O)(OH)2 as components of proton-conducting membranes is discussed. 相似文献
12.
《Electrochemistry communications》2001,3(8):467-471
Anodic fluorination of 1-methylpyrroles having electron-withdrawing groups at the 2-position was comparatively studied using Et3N•3HF and Et3N•2HF as a supporting electrolyte and a fluorine source. The use of Et3N•3HF gave trifluorinated products predominantly or selectively depending on solvents used while the use of Et3N•2HF provided the corresponding monofluorinated pyrrole derivatives in considerable amount along with the trifluorinated products regardless of the solvents. This is the first successful example of selective anodic fluorination of pyrroles. The effects of supporting electrolyte on product selectivity are discussed. 相似文献
13.
Yuriko Akiyama 《Journal of fluorine chemistry》2006,127(7):920-923
Ring-opening fluorination reactions of epoxides using tetrabutylammonium bifluoride (TBABF)-KHF2, or Et3N-3HF under microwave irradiation were applied for the introduction of a fluorine atom into the carbohydrate molecules. When TBABF-KHF2 was used as the fluorination reagent, a fluorine atom was introduced regioselectively and various functional groups can tolerate the conditions. When Et3N-3HF was used under microwave irradiation, the reaction time could be remarkably shortened compared with the conventional oil-bath heating. 相似文献
14.
Hirokatsu Nagura 《Tetrahedron》2009,65(8):1559-186
Electrochemical fluoro-selenenylation of electron-deficient olefins like α,β-unsaturated ester, carboxylic acid, amide, and phosphonate was successfully carried out by the anodic oxidation of diphenyl diselenide in the presence of olefins in Et3N·5HF/CH3NO2. The anodically generated benzeneselenenyl fluoride [PhSeF] equivalent was stable in the electrolytic solution, which resulted in the efficient fluoro-selenenylation. The fluoro-selenenylation products were shown to be potential useful fluoro-building blocks. 相似文献
15.
Hidekazu Touhara Junichi InaharaTomotaka Mizuno Yu YokoyamaSatoru Okanao Katsuaki YanagiuchIndrajit Mukopadhyay Shinji KawasakiFujio Okino Hirofusa ShiraiW.H. Xu T. KyotaniA. Tomita 《Journal of fluorine chemistry》2002,114(2):181-188
Multiwall carbon nanotubes (MWNTs) based on the template carbonization technique were fluorinated in a temperature range 323-473 K by elemental fluorine. The fluorination of the carbon nanotubes results in functionalization and modification of pristine nanotubes with respect to adsorption and electrochemical properties. Selective fluorination of the inner surface of the carbon nanotubes, brings about a decrease in the surface free energy of the inner surface of the tubes and an increase in colombic efficiency of Li/nanotubes rechargeable cells in an aprotic medium. Electrochemical fluoride-ion doping of fullerene C60 thin films (250-450 nm) was carried out in a fluoride-ion conductive solution, MeCN solution of 1 M Et4NF·4HF. Galvanostatic oxidation yielded C60Fca.1-3 where fluorine exists as a semi-ionic species in the cavity surrounded by C60 molecules without forming covalent CF bonds 相似文献
16.
A computational study of ion speciation in mixtures of protic ionic liquids with various molecular solvents: Insight into the solvent polarity and anion basicity 下载免费PDF全文
Jiayao Huang Aiping Fu Hongliang Li Hao Li Tianshu Chu Zonghua Wang 《International journal of quantum chemistry》2017,117(3):170-179
The ion pairing state of the ionic liquids greatly depends on the cosolvent which subsequently affects the properties and the functionalities. Density functional calculations have been performed to study the ion pairing formation process of protic ionic liquids (PILs) ([Et3NH][CH3SO3]/TEAMS or [Et3NH][CF3SO3]/TEATF) dissolved in different solvents. The clusters involving the cation, anion, and different number of solvent molecules have been used to simulate the contact ion pairs (CIPs) and the solvent‐separated ion pairs (SIPs) in the mixtures with varying solvent concentrations. The geometric, energetic data, and the natural bond orbital analysis suggest the smallest number of the water molecules required to break the TEAMS CIPs is four, while it is three for TEATF. This is consistent with the experimental prediction that if the mixture of TEAMS and water was replaced by TEATF and water, the transition process began at a lower water concentration. Furthermore, the calculated results also confirm that the weakly polar organic solvents favor the CIP form at all solvent concentrations, while the high polarity solvents promote dissociation of the CIP to generate the SIP form for particular PILs. The different separation nature of the given solvents can be interpreted in terms of their distinct hydrogen bond donor and acceptor abilities. 相似文献
17.
With propeller‐like shape, hexaphenylbenzene bromides display different recognition abilities for guest molecules in solid state. HBH can encapsulate CH2Cl2 or Et2O molecules selectively from different solvent systems. For DBH , the recognition pattern is dominated between themselves. In CH2Cl2/toluene/Et2O system, toluene molecule can be encapsulated selectively by MBH . In these supramolecular assemblies, bromine bonding plays an important role. 相似文献
18.
RhTp(cod) ( 1 ) and RhBp(cod) ( 2 ), almost inactive in CH2Cl2, became good catalysts of phenylacetylene polymerization in ionic liquids ([bmim]Cl, [bmim]BF4: bmim = 1‐butyl‐3‐methylimidazolium, [mokt]BF4: mokt = 1‐methyl‐3‐oktylimidazolium, [bumepy]BF4: 1‐butyl‐4‐methylpyridinium) and in CH2Cl2 in the presence of tetraammonium halides ([R4N]X, R = Bu, Et; X = Cl, Br). The highest yields of polyphenylacetylene with catalyst 1 were obtained in [bmim]Cl at 65°C (64% after 2 h) and in [mokt]BF4 at 20°C (56% after 24 h). In alcohols (CH3OH, (CH3)2CHOH, (CH3)3COH) as solvents, up to 100% of the polymer was produced. When a mixture of an ionic liquid and CH3OH was used as the reaction medium, the polymer yield was similar to the yield achieved in an ionic liquid only, but the molecular weight increased remarkably. Tetraammonium salts, [R4N]X, are co‐catalysts for 1 , and the yield of the polymer increased in the order [Et4N]Br < [Bu4N]Br < [Et4N]Cl < [Bu4N]Cl. Polymers with molecular weights from 6900 to 38 800 Da were obtained with catalyst 2 in [R4N]Br or [R4N]Cl, whereas in ionic liquids ([bmim]Cl, [bmim]BF4) the corresponding molecular weights were higher, from 51 300 to 60 300 Da. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
19.
Novel Hoveyda-type Ru-carbene complexes 7a,b and 8a,b tethering imidazolium tags at chelating isopropoxy group have been synthesized, and investigated their catalytic activities and recyclabilities in ring-closing metathesis (RCM) and cross metathesis (CM) in ionic liquids. They showed excellent catalytic activities for RCM of various dienes in [bmim][PF6]/CH2Cl2 (1/1, v/v). The recyclability of these catalysts is largely dependent on the tether length and the structures of imidazolium tag and ionic liquid, as well as the composition of the ionic solvent system. A combination of the 2-methylated imidazolium ion-tagged Ru-complex 7b with a mixture of [bdmim][PF6]/toluene (1/3, v/v) allowed several times recycling without significant loss of catalytic activity in RCM, however low recyclabilities were observed in CMs. 相似文献