- Radical Decarboxylative Carbometalation of Benzoic Acids: A Solution to Aromatic Decarboxylative Fluorination
-
Abundant aromatic carboxylic acids exist in great structural diversity from nature and synthesis. To date, the synthetically valuable decarboxylative functionalization of benzoic acids is realized mainly by transition-metal-catalyzed decarboxylative cross couplings. However, the high activation barrier for thermal decarboxylative carbometalation that often requires 140 °C reaction temperature limits both the substrate scope as well as the scope of suitable reactions that can sustain such conditions. Numerous reactions, for example, decarboxylative fluorination that is well developed for aliphatic carboxylic acids, are out of reach for the aromatic counterparts with current reaction chemistry. Here, we report a conceptually different approach through a low-barrier photoinduced ligand to metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation strategy, which generates a putative high-valent arylcopper(III) complex, from which versatile facile reductive eliminations can occur. We demonstrate the suitability of our new approach to address previously unrealized general decarboxylative fluorination of benzoic acids.
- Xu, Peng,López-Rojas, Priscila,Ritter, Tobias
-
supporting information
p. 5349 - 5354
(2021/05/05)
-
- Full continuous flow synthesis process of fluorine-containing aromatic hydrocarbon compounds
-
The invention provides a full continuous flow synthesis process of a fluorine-containing aromatic hydrocarbon compound, and belongs to the technical field of preparation of halogenated hydrocarbon carbocyclic organic compounds. Arylamine and hydrogen fluoride are pumped into a thermostat A and a thermostat B respectively and flow into a micro-channel reactor C for a salt forming reaction after constant temperature treatment, and a sulfuric acid solution of nitrosyl sulfuric acid is pumped into a thermostat D and flows into a micro-channel reactor E together with a salt forming product flowing out of the micro-channel reactor C for a diazotization reaction after constant temperature treatment. A product flows into a micro-channel reactor F to be subjected to a thermal decomposition reaction, is cooled by a cooler G and then enters a three-phase separator H to be continuously separated, nitrogen is discharged after being subjected to spraying deacidification, a fluorine-containing aromatic hydrocarbon crude product is subjected to continuous alkali washing, continuous drying and continuous rectification to obtain a fluorine-containing aromatic hydrocarbon finished product, and a hydrofluoric acid and sulfuric acid mixture is subjected to continuous distillation to obtain a product. The hydrogen fluoride and sulfuric acid are obtained. The full continuous flow synthesis process has the advantages of high reaction yield, excellent product quality, good production safety, less pollutant discharge and the like.
- -
-
Paragraph 0095-0108
(2021/04/07)
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- Pd-Co catalysts prepared from palladium-doped cobalt titanate precursors for chemoselective hydrogenation of halonitroarenes
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Bimetallic Pd-Co catalysts supported on the mixed oxides CoTiO3-CoO-TiO2 (CTO) were synthesized via the thermal reduction of Pd-doped cobalt titanates PdxCo1-xTiO3 and evaluated for the chemoselective hydrogenation of halonitroarenes to haloarene-amines. The nominal Pd mass percentage of the Pd-Co/CTO systems was varied from 0.0 to 0.50. After the thermal reduction of PdxCo1-xTiO3 at 500 °C for 3 h, Pd was completely reduced and Co was partially reduced, producing a mixture of ionic Co, metallic Co, and TiO2-rutile species to give the supported bimetallic catalysts. The metallic cobalt content increased with the Pd content of the precursor. The catalytic activity toward 4-chloronitrobenzene increased with the Pd content; however, >0.1 mass% Pd decreased the chemoselectivity toward 4-chloroaniline due to the formation of the hydrodehalogenation product—aniline. The 0.1Pd-Co/CTO system was used as a model catalyst to produce haloarene-amine building blocks for linezolid, loxapine, lapatinib, and sorafenib with >98% conversion, 96% chemoselectivity, and no hydrohalogenation products. Finally, recycling tests of the 0.1Pd-Co/CTO catalyst showed loss of activity and selectivity during the third cycle due to catalyst deactivation. Regeneration treatments, every two catalytic cycles, allowed six operation cycles without loss of chemoselectivity and only a slight decrease in catalytic activity during the last cycle.
- Bustamante, Tatiana M.,Dinamarca, Robinson,Torres, Cecilia C.,Pecchi, Gina,Campos, Cristian H.
-
-
- Reactions of Arylsulfonate Electrophiles with NMe4F: Mechanistic Insight, Reactivity, and Scope
-
This paper describes a detailed study of the deoxyfluorination of aryl fluorosulfonates with tetramethylammonium fluoride (NMe4F) and ultimately identifies other sulfonate electrophiles that participate in this transformation. 19F NMR spectroscopic monitoring of the deoxyfluorination of aryl fluorosulfonates revealed the rapid formation of diaryl sulfates under the reaction conditions. These intermediates can proceed to fluorinated products; however, diaryl sulfate derivatives bearing electron-donating substituents react very slowly with NMe4F. Based on these findings, aryl triflate and aryl nonaflate derivatives were explored, since these cannot react to form diaryl sulfates. Aryl triflates were found to be particularly effective electrophiles for deoxyfluorination with NMe4F, and certain derivatives (i.e., those bearing electron-neutral/donating substituents) afforded higher yields than their aryl fluorosulfonate counterparts. Computational studies implicate a similar mechanism for deoxyfluorination of all the sulfonate electrophiles.
- Schimler, Sydonie D.,Froese, Robert D. J.,Bland, Douglas C.,Sanford, Melanie S.
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p. 11178 - 11190
(2018/09/12)
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- A Predictive Model for the Decarboxylation of Silver Benzoate Complexes Relevant to Decarboxylative Coupling Reactions
-
Decarboxylative coupling reactions offer an attractive route to generate functionalized arenes from simple and readily available carboxylic acid coupling partners, yet they are underutilized due to limitations in the scope of carboxylic acid coupling partner. Here we report that the field effect parameter (F) has a substantial influence on the rate of decarboxylation of well-defined silver benzoate complexes. This finding provides the opportunity to surpass current substrate limitations associated with decarboxylation and to enable widespread utilization of decarboxylative coupling reactions.
- Crovak, Robert A.,Hoover, Jessica M.
-
p. 2434 - 2437
(2018/02/28)
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- Decarbonylation of Aromatic Aldehydes and Dehalogenation of Aryl Halides Using Maghemite-Supported Palladium Catalyst
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A facile decarbonylation reaction of a variety of aromatic and heteroaromatic aldehydes using maghemite-supported palladium catalyst has been developed. The magnetic properties of catalyst facilitated an easy and efficient recovery of the catalyst from the reaction mixture using an external magnet. It was found that the catalyst could be reused up to four consecutive catalytic runs without a significant change in activity. In addition, the catalyst was also very effective in the dehalogenation of aryl halides. This is the first report on efficient utilization of directly immobilized Pd on maghemite in decarbonylation and dehalogenation reactions.
- Ajda?i?, Vladimir,Nikoli?, Andrea,Simi?, Stefan,Manojlovi?, Dragan,Stojanovi?, Zoran,Nikodinovic-Runic, Jasmina,Opsenica, Igor M.
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p. 119 - 126
(2017/12/27)
-
- METHOD FOR AROMATIC FLUORINATION
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Disclosed is a fluorination method comprising providing an aryl fluorosuifonate and a fluorinating reagent to a reaction mixture; and reacting the aryl fluorosuifonate and the fluorinating reagent to provide a fluorinated aryl species. Also disclosed is a fluorination method comprising providing, a salt comprising a cation and an aryloxyiate, and SO2F2 to a reaction mixture; reacting the SO2F2 and the ammonium salt to provide a fluorinated aryl species. Further disclosed a fluorination method comprising providing a compound having the structure Ar-OH to a reaction mixture; where A is an aryl or heteroaryl; providing SO2F2 to the reaction mixture; providing a fluorinating reagent to the reaction mixture; reacting the SO2F2, the fluorinating reagent and the compound having the structure Ar-OH to provide a fluorinated aryl species having the structure Ar-F.
- -
-
Paragraph 0047-0049
(2017/12/18)
-
- Nucleophilic deoxyfluorination of phenols via aryl fluorosulfonate intermediates
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This report describes a method for the deoxyfluorination of phenols with sulfuryl fluoride (SO2F2) and tetramethylammonium fluoride (NMe4F) via aryl fluorosulfonate (ArOFs) intermediates. We first demonstrate that the reaction of ArOFs with NMe4F proceeds under mild conditions (often at room temperature) to afford a broad range of electronically diverse and functional group-rich aryl fluoride products. This transformation was then translated to a one-pot conversion of phenols to aryl fluorides using the combination of SO2F2 and NMe4F. Ab initio calculations suggest that carbon-fluorine bond formation proceeds via a concerted transition state rather than a discrete Meisenheimer intermediate.
- Schimler, Sydonie D.,Cismesia, Megan A.,Hanley, Patrick S.,Froese, Robert D.J.,Jansma, Matthew J.,Bland, Douglas C.,Sanford, Melanie S.
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p. 1452 - 1455
(2017/02/10)
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- Continuous production method for industrially preparing 2,3-difluorobenzotrifluoride and 3,4-difluorobenzonitrile
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The invention discloses a continuous production method for industrially preparing 2,3-difluorobenzotrifluoride and 3,4-difluorobenzonitrile. The preparation process of the 2,3-difluorobenzotrifluoride comprises the preparation step of an intermediate raw material for benzene sulfonamide and benzenesulfonylurea herbicides, and the preparation process of the 3,4-difluorobenzonitrile comprises the preparation step of a cthalofop-butyl intermediate raw material. The method is suitable for industrial production; and compared with the prior art, the method has the advantages of low cost, high production method and less pollution.
- -
-
Paragraph 0022; 0023
(2018/03/24)
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- Reactions of aromatic compounds with xenon difluoride
-
Reactions of substituted benzenes C6H5R (R = Me, F, Cl, Br, CF3, NO2) with xenon difluoride in the presence of boron trifluoride–diethyl ether complex in weakly acidic (1,1,1,3,3-pentafluorobutane) and weakly basic media (acetonitrile) have been studied. These reactions lead to the formation of fluorobenzene derivatives FC6H4R (isomer mixture) together with isomeric difluorobenzenes and fluorinated and non-fluorinated biphenyls. The results have been compared with previously reported data obtained in other solvents using other catalysts.
- Bardin,Adonin, N. Yu.
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p. 1400 - 1407
(2016/11/29)
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- Fluorination of aromatic compounds with xenon difluoride in the presence of boron trifluoride etherate
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Fluorination of benzene with the XeF2 - BF3?Et2O system in acetonitrile at low temperatures affords fluorobenzene in 18% yield, the conversion of benzene being 92%. The rest products are di-, tri-, tetra-, and polyphenyls with different fluorination pattern. Toluene and chloro- and bromobenzenes are fluorinated predominantly at the ortho and para positions. Fluorination of 4-nitroanisole affords 2-fluoro-4-nitroanisole in 73% yield.
- Fedorov,Zubarev,Mortikov, V. Yu.,Rodinovskaya,Shestopalov
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p. 1049 - 1052
(2016/02/09)
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- A catalytic borylation/dehalogenation route to o -fluoro arylboronates
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A two-step Ir-catalyzed borylation/Pd-catalyzed dehalogenation sequence allows for the net synthesis of fluoroarenes where the boronic ester is ortho to fluorine. Key elements of this approach include the use of a halogen para to the fluorine to block meta Ir-catalyzed borylation and the chemoselective Pd-catalyzed dehalogenation by KF activated polymethylhydrosiloxane (PMHS).
- Jayasundara, Chathurika R. K.,Unold, Jason M.,Oppenheimer, Jossian,Smith, Milton R.,Maleczka, Robert E.
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p. 6072 - 6075
(2015/01/09)
-
- Silver-mediated fluorination of potassium aryltrifluoroborates with Selectfluor Dedicated to Professor Andrea Vasella on the occasion of his 71st birthday
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A simple and practical procedure for the silver-mediated fluorination of aryl- and heteroaryltrifluoroborates with electrophilic fluorine from Selectfluor and LiOH·H2O is presented. The reaction procedure is simple and easy to set up, the process produces fluorinated arenes and heteroarenes in good to excellent yields and a wide range of electronically and structurally diverse substrates are tolerated.
- Dubbaka, Srinivas Reddy,Narreddula, Venkateswara Reddy,Gadde, Satyanarayana,Mathew, Thresen
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p. 9676 - 9681
(2015/01/08)
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- Direct fluorination of cyclic carbonates and closo-K2[B 12H12] in a slug-flow ministructured reactor
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A novel minireactor for direct fluorination of organic and inorganic substances was tested. The reactor consists of nickel-coated copper blocks with mechanically machined 1 mm channels and is equipped with an active cooling system. The direct fluorination of ethylene carbonate and propylene carbonate is described. For the fluorinated propylene carbonate, the NMR data of various fluorinated isomers were determined. The Gibbs reaction energies for the direct fluorination of ethylene and propylene carbonate were calculated at the reliable G3 level of theory. The excellent decomposition stability of the cyclic carbonates against high fluorine and HF concentrations also qualifies them as good solvents for direct fluorination processes, especially for ionic substrates. In this respect, the direct fluorination of the inorganic salt closo-K2[B12H12] in cyclic carbonates is presented.
- Hill, Mathias,Baron, Patrick,Cobry, Keith,Goll, Sascha K.,Lang, Philipp,Knapp, Carsten,Scherer, Harald,Woias, Peter,Zhang, Pengcheng,Krossing, Ingo
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p. 292 - 301
(2013/08/23)
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- Mild copper-mediated fluorination of aryl stannanes and aryl trifluoroborates
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This communication describes a mild copper-mediated fluorination of aryl stannanes and aryl trifluoroborates with N-fluoro-2,4,6-trimethylpyridinium triflate. This protocol demonstrates broad substrate scope and functional group tolerance, and does not require the use of any noble metal additives. The reaction is proposed to proceed via an arylcopper(III) fluoride intermediate.
- Ye, Yingda,Sanford, Melanie S.
-
supporting information
p. 4648 - 4651
(2013/05/09)
-
- Process for the Synthesis of Highly Active Binary Metal Fluoride as a Fluorinating Agent for Aromatics
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The subject invention relates to a process for the synthesis of highly active binary metal fluoride system for the fluorination of aromatic compounds. Fluorinated aromatic compounds are valuable synthons for the chemical synthesis of pharmaceutical drugs and novel polymers. Fluorobenzene is used to control carbon content in steel manufacturing, is an intermediate for pharmaceuticals, pesticides and other organic compounds. Fluorobenzene is typically produced by the reaction of aniline and sodium nitrite in the presence of hydrogen fluoride. The present invention relates to a process for the synthesis of highly active binary metal fluoride system consists of copper (II) fluoride and aluminum (III) fluoride for the fluorination of aromatic compounds in gas phase and recycling of the reagent, in situ, using O2 and HF.
- -
-
Page/Page column 6-7
(2010/02/17)
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- Formation of arf from lpdar(f): catalytic conversion of aryl triflates to aryl fluorides
-
Despite increasing pharmaceutical importance, fluorinated aromatic organic molecules remain difficult to synthesize. Present methods require either harsh reaction conditions or highly specialized reagents, making the preparation of complex fluoroarenes ch
- Watson, Donald A.,Su, Mingjuan,Teverovskiy, Georgiy,Zhang, Yong,Garcia-Fortanet, Jorge,Kinzel, Tom,Buchwaldf, Stephen L.
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scheme or table
p. 1661 - 1664
(2010/06/16)
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- Regioselective arene functionalization: Simple substitution of carboxylate by alkyl groups
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Arenes with various alkyl side-chains were synthesized in high yields and excellent regioselectivities. Starting from toluic and naphthoic acids, the carboxylate group was conveniently substituted by alkyl halides by Birch reduction and subsequent decarbonylation. The method is characterized by inexpensive starting materials and reagents, and methylation of arenes was realized. Besides simple alkyl substituents, the scope of arene functionalization was extended by benzyl, fluoro, amino, and ester groups. We were able to control the alkylation of 1-naphthoic acid during Birch reduction by the addition of tert-butanol. This allowed the regioselective synthesis of mono and bis-substituted naphthalenes from the same starting material.
- Krueger, Tobias,Vorndran, Katja,Linker, Torsten
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experimental part
p. 12082 - 12091
(2010/05/17)
-
- An epoxidation approach to a chiral lactone: Application of the Shi epoxidation
-
The large-scale epoxidation of the alkene 7 with the organo-catalyst, Epoxone (10), and Oxone as the oxidant is described. This is the first large-scale application of the Shi epoxidation methodology. The large-scale preparation of the catalyst 10 is also described. The potassium salt of the unsaturated acid precursor 7 was prepared by a Suzuki coupling from 3-fluorobenzyl chloride and the vinylborane 8 derived from 4-pentynoic acid.
- Ager, David J.,Anderson, Ken,Oblinger, Eric,Shi, Yian,Vanderroest, James
-
-
- Method For Preparation Of A Fluoroaromatic Compound From An Aminoaromatic Compound
-
The invention relates to a method for preparation of fluorinated aromatic compounds from the corresponding amines by replacement of the amino group with a fluorine atom. The method of preparation of a fluoroaromatic compound from an aromatic compound with at least one amino group on the aromatic ring is characterized by the reaction of said aromatic amine compound with a nitrosating agent in the presence of a source of boron trifluoride in an organic medium, and carrying out a thermal treatment of the reaction medium comprising the diazonium salt thus obtained to give the fluoroaromatic compound directly by decomposition of the diazonium salt without intermediate isolation thereof.
- -
-
Page/Page column 9
(2008/06/13)
-
- Method for separating substances
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An objective of the present invention is to provide electrophoretic separation methods and devices that enable the various features of a substrate surface that comes in contact with an electrophoresis medium to be controlled. The present invention provides methods for electrophoresing substances, which comprises the steps of: (a) adding a substance to be analyzed to an electrophoresis medium retained in a substrate, whose surface that has come in contact with the electrophoresis medium has been coated with a polymer membrane; and (b) adding electrophoretic pressure to the electrophoresis medium. For example, the use of a plasma-polymerized membrane allows the formation of a membrane with homogeneous quality and thickness on the surface of an arbitrary shape. In addition, desired characteristics can be conferred on the surface through selection of monomeric substances. Protein adsorption onto micro-chips can be effectively prevented as well.
- -
-
-
- One-pot fluoro-de-diazoniation of anilines in organic medium
-
Treatment of anilines with tert-butyl nitrite in the presence of boron trifluoride in ortho-dichlorobenzene leads to in situ fluoro-de-diazoniation and affords the corresponding fluoroaromatics with fair yields. This process, conducted in organic medium without Broensted acids, does not require isolation of hazardous diazonium salts and reduces the amounts of wastes. The results of the first screening are given.
- Garel, Laurent,Saint-Jalmes, Laurent
-
p. 5705 - 5708
(2007/10/03)
-
- Oxidative fluorination of aromatic derivatives by copper (II) fluoride and silver (I) fluoride
-
The subject invention provides methods of fluorinating an aromatic or chloroaromatic compound comprising combining an aromatic compound, a chloroaromatic compound, a mixture of aromatic compounds, a mixture of chloroaromatic compounds, or a mixture of chloroaromatic and aromatic compounds and a fluorinating composition comprising at least one active fluorinating agent selected from the group consisting of CuF2, AgF, HgF2, TeF4, MnF4, FeF3, and CoF2-4 and at least one support selected from the group consisting of activated carbon, ZnF2, CaF2, MgF2, AIF3, and combinations of activated carbon, ZnF2, CaF2, MgF2, or AlF3.
- -
-
Page/Page column 5
(2008/06/13)
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- Room-temperature catalytic hydrodefluorination of C(sp3)-F bonds
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Room-temperature catalytic hydrodefluorination of the strong C(sp3)-F bonds in benzotrifluorides and fluoropentane is catalyzed by Et3Si[B(C6F5)4] and uses Et3SiH as the source of H. Ar-CF
- Scott, Valerie J.,Celenligil-Cetin, Remle,Ozerov, Oleg V.
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p. 2852 - 2853
(2007/10/03)
-
- A product analytical study of the thermal and photolytic decomposition of some arenediazonium salts in solution
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Products of thermal and photochemical reactions of eleven arenediazonium tetrafluoroborates in various solvents have been analyzed. All compounds in most solvents undergo unimolecular heterolysis to give singlet aryl cations which are captured by solvent. This mechanism is dominant for arenediazonium ions without electron-withdrawing substituents in all solvents, and the only reaction observed in water. Additionally, appreciable yields of fluoroarenes are obtained by fluoride abstraction by the aryl cation from fluorinated solvents and from tetrafluoroborate in fluorinated solvents. Yields from photochemical processes are very similar to those from thermal reactions indicating that the main reactions proceed through common or very similar intermediates. Aryl cations formed from ion-paired diazonium ions may react with the counterion, but fragmentation of dissociated diazonium ions leads only to solvent-derived product. Some arenediazonium ions in some solvents undergo an alternative radical reaction leading principally to hydrodediazoniation. It is proposed that this reaction involves initial rate-limiting electron transfer from ethanol to the arenediazonium ion followed rapidly by homolysis of the resultant aryldiazenyl radical. Within the same solvent cage, the aryl radical then either abstracts an α-hydrogen from the ethanol radical cation generated in the first step to give the reduction product and protonated acetaldehyde, or combines with it at the oxygen to give a protonated aryl ethyl ether.
- Canning, Peter S. J.,Maskill, Howard,McCrudden, Katharine,Sexton, Brian
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p. 789 - 800
(2007/10/03)
-
- Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides
-
Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.
- Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.
-
p. 402 - 415
(2007/10/03)
-
- Fluorination of aromatic compounds from 1-aryl-3,3-dimethyltriazenes and fluoride anions in acidic medium: 1. A model for 18F labelling
-
Decomposition of 1-aryl-3,3-dialkyltriazenes by strong and non-nucleophilic acids (CF3SO3H, H2SO4) can be achieved at 90°C in carbon tetrachloride, in the presence of sub-stoichiometric amounts of fluoride anions. Yields of fluoroarenes up to 39% (versus F-) can be reached under these conditions, within 15-30min and without contamination of the fluorinated compounds by inseparable by-products. Such conditions and results enable an adaptation to radiofluorination with 18F-.
- Pages, Thierry,Langlois, Bernard R.
-
p. 321 - 327
(2007/10/03)
-
- Process for the preparation of halogenated derivatives and Lewis acid base catalysts thereof
-
A process for the preparation of halide compounds, preferably aryl halides, by contacting a gaseous mixture of hydrohalic acid and a compound selected from an aryl halogen formate, an aryl carbonate and equivalents thereof with a Lewis acid catalyst.
- -
-
-
- Preparation process of fluorine substituted aromatic compound
-
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.
- -
-
-
- Direct fluorination of toluene using elemental fluorine in gas/liquid microreactors
-
Direct fluorination of toluene, pure or dissolved in either acetonitrile or methanol, using elemental fluorine was investigated in gas/liquid microreactors, namely a falling film microreactor and a micro bubble column. The experiments included measurements at high substrate concentrations and at high fluorine contents diluted in a nitrogen carrier gas, e.g. up to 50vol.% fluorine. Results obtained were compared to the performance of a laboratory bubble column which served as a technological benchmark. Due to the formation of liquid layers of only a few tens of micrometers thickness, the microreactors provide very large interfacial areas, e.g. up to 40,000m2/m3. These values exceed by far those of the laboratory bubble column as well as all other devices applied in practice. The potential for enhancing mass and heat transfer was verified by several experiments resulting in an increase in conversion and selectivity for the microreactors compared to the laboratory benchmark. For the falling film microreactor, yields of up to 28% of monofluorinated ortho and para products for a degree of toluene conversion of 76% were obtained. These values are of the same order as described for the industrially applied Schiemann process. Space-time yields of the microreactors, when referred to the reaction channel volume, were orders of magnitude higher than those of the laboratory bubble column. Taking into account the construction material needed, the corresponding figures of merit, for an idealized geometry as well as the existing total reactor geometry, still indicate technological and economic benefits. A variation of operating conditions for the direct fluorination revealed that conversion can be increased in the microreactors by using higher fluorine-to-toluene ratios and reaction temperatures. The choice of solvent is also essential, with acetonitrile yielding much better results than methanol.
- J?hnisch,Baerns,Hessel,Ehrfeld,Haverkamp,L?we,Wille,Guber
-
p. 117 - 128
(2007/10/03)
-
- The synthesis of [18F]fluoroarenes from the reaction of cyclotron-produced [18F]fluoride ion with diaryliodonium salts
-
Diaryliodonium salts have been shown to react with fluoride ion at 80°C in acetonitrile to generate aryl fluorides. The regioselectivity is controlled electronically and by the bulk of the ortho-substituents on the rings, with the latter the dominant factor such that electron-rich rings can be fluorinated. ortho-Substituted aryl fluorides can be selectively produced from unsymmetrical diaryliodonium salts. The process has been used to synthesise [18F] labelled aromatics by the use of cyclotron generated [18F]fluoride ion.
- Shah, Aneela,Pike, Victor W.,Widdowson, David A.
-
p. 2043 - 2046
(2007/10/03)
-
- Deaminative Fluorination of Anilines with Silicon Tetrafluoride: Utility of Silicon Tetrafluoride as a Fluorine Source
-
Application of silicon tetrafluoride to deaminative fluorination of anilines as a fluorine source is investigated. A diazotization of anilines proceeds with silicon tetrafluoride and tbutyl nitrite under mild condition and the following fluorodediazoniation affords fluoroarenes in good yields.
- Tamura, Masanori,Shibakami, Motonari,Sekiya, Akira
-
p. 725 - 727
(2007/10/03)
-
- Dehalogenation of organic halides by flash vacuum pyrolysis over magnesium: A versatile synthetic method
-
Flash vacuum pyrolysis over magnesium at 600°C results in efficient dehalogenation of a variety of organic halides and provides a preparatively useful method for C-C bond formation and other reactions.
- Aitken, R. Alan,Hodgson, Philip K. G.,Oyewale, Adebayo O.,Morrison, John J.
-
p. 1163 - 1164
(2007/10/03)
-
- Hydrogen atom attack on fluorotoluenes: Rates of fluorine displacement
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Rates of hydrogen atom attack on o-fluorotoluene (o-FTOL) and m-fluorotoluene (m-FTOL) at temperatures of 988-1144 K and pressures of 2-2.5 bar have been determined in a single-pulse shock tube study. Hydrogen atoms, generated from the decomposition of hexamethylethane, were allowed to react with the substrates and the characteristic products observed. Rate constants for two reaction channels, displacement of fluorine or methyl, were determined relative to displacement of methyl from 1,3,5-trimethylbenzene (135TMB). Evidence is presented that abstraction of F is unimportant over the studied temperature range. With k(H + 135TMB → m-xylene + CH3) = 6.7 × 1013 exp(-3255/T) cm3 mol-1s-1, the following rate expressions have been derived: k(H + o-FTOL → C6H5CH3 + F) = 8.38 × 1013 exp(-6041/T) cm3 mol-1s-1; (1012-1142 K) k(H + o-FTOL → C6H5F + CH3) = 2.37 × 1013 exp(-2938/T) cm3 mol-1s-1; (988-1142 K) k(H + m-FTOL → C6H5CH3 + F) = 1.33 × 1014 exp(-6810/T) cm3 mol-1s-1; (1046-1144 K) k-(H + m-FTOL → C6H5F + CH3) = 2.04 × 1013 exp(-3104/T) cm3 mol-1s-1; (1008-1144 K) Uncertainties in the relative rate constants are estimated to be factors of about 1.1, while the above absolute values have estimated expanded uncertainties of about a factor of 1.4 in rate, 10 kJ mol-1 in the activation energy, and a factor of 3 in the A-factor. The present data are compared with relevant literature data. From our data and the thermochemistry, a model of the elementary steps comprising displacement of F is developed. On the basis of the model fit to our data, rate constants for the addition of atomic fluorine to toluene at 1100 K are derived. Rate expressions for fluorination reactions of toluene are also determined. The significance of the present results is discussed in the context of the formation of fluorinated byproducts in high-temperature systems.
- Manion, Jeffrey A.,Tsang, Wing
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p. 263 - 273
(2007/10/03)
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- Facile preparation of aromatic fluorides by deaminative fluorination of aminoarenes using hydrogen fluoride combined with bases
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One-pot deaminative fluorination of aminoarenes including heteroaromatics, namely, diazotization of aminoarenes followed by in situ fluoro-dediazoniation of the corresponding diazonium ions, was successfully accomplished to produce fluoroarenes in high yields by using hydrogen fluoride combined with base solutions. The diazotization stage has been found to play the most important part in yielding fluoroarenes effectively. It was greatly influenced by the composition of the HF solution and enhanced by employing appropriate amounts of bases such as pyridine under carefully controlled conditions. The fluoro-dediazoniation stage was effectively accelerated photochemically to afford fluoroarenes having polar substituents such as hydroxyl, nitro and so on in high yields.
- Yoneda,Fukuhara
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- Deaminative fluorination of anilines using potassium hydrogen fluoride and silicon tetrafluoride
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It has been found that the combination of potassium hydrogen fluoride and silicon tetrafluoride works as an efficient fluorinating agent for the deaminative fluorination of anilines. A one-pot diazotization of anilines followed by fluoro-dediazoniation proceeds with this combination of the reagents and t-butyl nitrite to afford fluoroarenes.
- Tamura, Masanori,Shibakami, Motonari,Kurosawa, Shigeru,Arimura, Takashi,Sekiya, Akira
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- Direct Formation of (Haloaryl)copper Nucleophiles from Haloiodobenzenes and Active Copper
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(o-Halophenyl)-, (m-halophenyl)-, and (p-halophenyl)copper reagents have been formed in moderate to high yields at room temperature from active copper and the corresponding haloiodobenzenes.These reagents have been cross-coupled with a variety of alkyl and acyl halides to produce the respective haloarenes and haloaryl ketones.Remarkably, (o-fluorophenyl)- and (o-chlorophenyl)copper are produced in good yields by this procedure without undergoing elimination to form benzyne making this approach a convenient method for generating o-halophenyl nucleophiles.
- Ebert, Greg W.,Pfennig, Deborah R.,Suchan, Scott D.,Donovan, Thomas A.,Aouad, Emmanuel,et al.
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p. 2361 - 2364
(2007/10/02)
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- Aromatic nucleophilic fluorination
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A process for halogen exchange fluorination or fluoro-denitration of aromatic compounds having at least one replaceable non-fluorine halogen or nitro substituent with an anhydrous substantially molten alkali metal acid fluoride composition wherein the alkali metal is potassium, rubidium or cesium.
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- Aryl fluoride syntheses involving reactions of aryllead triacetates with boron trifluoride-diethyl ether complex
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Aryllead(IV) triacetates react at room temperature with BF3.Et2O to give the corresponding aryl fluoride in moderate to good yields; triarylboroxines, electron rich aryltrimethylsilanes and some arenes, which yield aryllead triacetates in acid catalysed reactions with lead tetraacetate, are converted directly into aryl fluorides when stirred with lead tetraacetate in BF3.Et2O. An investigation of the mechanism of the fluoro-deplumbation reaction indicates that it probably proceeds by acid catalysed heterolytic cleavage of the C-Pb bond to produce an aryl cation.
- De Meio,Morgan,Pinhey
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p. 8129 - 8138
(2007/10/02)
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- Facile conversion of arenediazonium salts to the corresponding fluoroarenes using boron trifluoride diethyl ether complex
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The conversion of various arenediazonium salts 1 to the corresponding fluoroarenes 2 has been achieved in good yields under mild conditions in boron trifluoride diethyl ether complex.
- Shinhama,Aki,Furuta,Minamikawa
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p. 1577 - 1582
(2007/10/02)
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- Mass spectrometric investigations on phenylacetic acid derivatives, IV: Loss of ortho-substituents from ionized phenyl-2-propanones upon electron impact
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In the gas phase, the phenyl-2-propanone molecules 2a-4a lose upon electron impact chloro-, bromo-, and iodo-radicals specifically at the orthopOsition of the phenyl group giving rise to strong (M-Hal.)+-ions (70/12 eV; 1st and 2nd FFR) of identical structure as confirmed by their MIKE-CAD-spectra. The daughter ions at m/z 133 from o-chlorophenyl-2-propanone (2a) and 2,2-dimethyl-2,3-dihydro[b]furane (11) are structurally similar but not identical (similarity index 99.8). The collisionally activated (2nd FFR) (M-Br.)+-ions from o-bromophenyl-2-propanone (3a) and 1-bromo-1-phenyl-2-propanone (12) produce virtually congruent spectra. The most impOrtant subsequent fragmentation of the (M-Hal-)+-ions from 2a-4a is the loss of CO which incorporates the C-atom of the carbonyl group exclusively (13C labelling). Mechanistic aspects of the fragmentation sequences are discussed (Figs. 5 and 8).
- Striegel,Mayer,Wiegrebe,Schlunegger,Siegrist,Aebi
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p. 751 - 760
(2007/10/02)
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- PREPARATION OF FLUOROTOLUENE BY REACTION OF METHYLCYCLOPENTADIENE WITH DIFLUOROCARBENE GENERATED FROM DIFLUOROCHLOROMETHANE UNDER CONDITIONS OF PULSED GAS COMPRESSION
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Copyrolysis of difluorochloromethane with methylcyclopentadiene under conditions of pulsed gas compression at 924-1157 K takes place with the participation of difluorocarbene and a mixture of isometric fluorotoluenes with a total yield of 66-68percent is formed.In the absence of CHClF2, methylcyclopentadiene under conditions of pulsed compression at 1019-1190 K undergoes partial transformation into benzene and cyclopentadiene.
- Kuptsova, T. S.,Kolbanovskii, Yu. A.,Shapiro, E. A.,Nefedov, O. M.
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p. 589 - 592
(2007/10/02)
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- Gas-phase alkylation of fluorobenzene and substituted fluorobenzene by (CH3)2F+ ions
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The gas-phase methylation of selected fluorobenzenes by (CH3)2F+ ions has been investigated by a combination of mass spectrometric and radiolytic techniques. The results are compared with those of related alkylation reactions, both in the gas phase and in solution.
- Attina,Ricci
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p. 6775 - 6778
(2007/10/02)
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- A Facile Preparation of Aryl Triflates. Decomposition of Arenediazonium Tetrafluoroborate Salts in Trifluoromethanesulfonic Acid
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The thermal or photochemical decomposition of arenediazonium tetrafluoroborate salts n trifluoromethanesulfonic acid, with or without organic bases such as pyridine, provides aryl triflates in high yields.
- Yoneda, Norihiko,Fukuhara, Tsuyoshi,Mizokami, Takao,Suzuki, Akira
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p. 459 - 460
(2007/10/02)
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- Aryl Fluorides from the Reaction of Boron Trifluoride with Aryl-lead(IV) Triacetates, which may be generated in situ from Aryltrimethylsilanes, Triarylboroxines, and Arenes
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Aryl-lead(IV) triacetates react at room temperature with BF3*Et2O to give the corresponding aryl fluoride in moderate to good yields; triarylboroxines, electron-rich aryltrimethylsilanes, and some arenes, which yield aryl-lead(IV) triacetates in acid catalysed reactions with lead tetra-acetate, may be converted directly into aryl fluorides when stirred with lead tetra-acetate in BF3*Et2O.
- Meio, Giuseppe V. De,Pinhey, John T.
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p. 1065 - 1066
(2007/10/02)
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- THE REACTION OF FLUOROXYSULFATE, SO4F(1-), WITH AROMATIC COMPOUNDS: CATLYSIS BY ACIDS
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The effects of the acid catalysts HF, H2SO4, BF3, CF3SO3H, FSO3H, and SbF5*FSO3H on the reactions of CsSO4F with toluene, nitrobenzene and naphthalene in CH3CN have been studied.The catalysts in general accelerate reaction and enhance yields of ring-fluorinated products.Efficacity roughly parallels H0 of the acids, though H2SO4 is more effective than stronger acids for fluorination of naphthalene.Combined room temperature yields of fluorine-substituted products are as much as 45-50 percent for toluene and naphthalene and up to 30 percent for nitrobenzene.The predominant products are o-fluorotoluene, 1-fluoronaphthalene, and m-fluoronitrobenzene.With naphthalene the isomer selectivity is considerably less than in the absence of catalyst.Low yields ( = 10 percent) of monomeric oxygenated products are obtained, along with considerable oxygen- and fluorine-containing dimers and higher polymers.The results are interpreted in terms of acid-catalyzed electrophilic fluorination or oxygenation, followed by further fluorination and/or freeradical-induced oxidative coupling of the oxygenated products.
- Appelman, Evan H.,Basile, Louis J.,Hayatsu, Ryoichi
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p. 189 - 198
(2007/10/02)
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- Reaction of Acetyl Hypofluorite with Aromatic Mercury Compounds: a New Selective Fluorination Method
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Aromatic fluorine compounds are prepared in acetic acid from the corresponding mercury compounds and acetyl hypofluorite.
- Visser, Gerard W. M.,Halteren, Bert W. v.,Herscheid, Jacobus D. M.,Brinkman, Gerard A.,Hoekstra, Arend
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p. 655 - 656
(2007/10/02)
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- A comparison of the relative binding energie of H(+) and NO(+) to aromatic and haloaromatic bases by high pressure mass spectrometry
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Proton transfer equilibria (B1H(+) + B2 B1 + B2H(+)) and NO(+) transfer equilibria (B1NO(+) + B2 B1 + B2NO(+)) have been studied for the following bases B, benzene, toluene, o-, m-, and p-xylene.NO(+) transfer equilibria for fluoro- and chlorobenzene have also been studied.Pulsed electron beam, high-pressure ion source mass spectrometry has been used to obtain the equilibrium constant K and hence the free energy changes ΔG0 and from van't Hoff plots, ΔH0 and ΔS0.Entropy changes are in general much smaller for NO(+) transfer than for H(+) transfer but the magnitude of the changes in the proton affinity and NO(+) affinity of toluene caused by a fluorine substituent is about the same, even though the absolute value of the proton affinity is greater by a factor of 4.The position of the F substituent on toluene has a marked effect on proton affinity but no effect on NO(+) affinity.The latter appears to be responsive only to the inductive effect.
- Stone, John A.,Splinter, Dena E.,Kong, Soon Yau
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p. 910 - 915
(2007/10/02)
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