108-86-1Relevant articles and documents
Gilman,Brown
, p. 1181,1185 (1930)
A convenient new method for the bromination of deactivated aromatic compounds
Duan, Jianxin,Zhang, Lian Hao,Dolbier Jr., William R.
, p. 1245 - 1246 (1999)
Treatment of deactivated aromatic compounds with N-bromosuccinimide in trifluoroacetic acid solvent in the presence of sulfuric acid gave the corresponding monobromoaromatic compounds in good to excellent yields.
C?I-Selective Cross-Coupling Enabled by a Cationic Palladium Trimer
Diehl, Claudia J.,Scattolin, Thomas,Englert, Ulli,Schoenebeck, Franziska
, p. 211 - 215 (2019)
While there is a growing interest in harnessing synergistic effects of more than one metal in catalysis, relatively little is known beyond bimetallic systems. This report describes the straightforward access to an air-stable Pd trimer and presents unambiguous reactivity data of its privileged capability to differentiate C?I over C?Br bonds in C?C bond formations (arylation and alkylation) of polyhalogenated arenes, which typical Pd0 and PdI-PdI catalysts fail to deliver. Experimental and computational reactivity data, including the first location of a transition state for bond activation by the trimer, are presented, supporting direct trimer reactivity to be feasible.
Vibrational Spectroscopy and Photodissociation Properties of Ions As Determined by Two-Laser Photodissociation Techniques.
Honovich, Jeffrey P.,Dunbar, Robert C.
, p. 3755 - 3758 (1983)
Iodobenzene, bromobenzene, and m-iodotoluene cations trapped in an ion cyclotron resonance (ICR) mass spectrometer undergo an enhanced visible photodissociation process in the presence of infrared irradiation.The infrared wavelength dependence in the 9.7-10.7-μm region for this effect exhibits features wich relate to the infrared spectroscopy of these ions.The variation in extent of the infrared enhancement with visible wavelength is interpreted as reflecting two different mechanisms: at short wavelengths the enhancement is attributed to changes invisible-absorption cross section with increasing internal energy and gives a useful means of observing such effects, while at long wavelengths the enhancement is attributed to a perturbation of the two-photon dissociation kinetics.The photodissociation rates of several other ions were shown not to undergo an enhancement effect when irradiated with the infrared laser.
A study on Zr-Ir multiple bonding active for C-H bond cleavage
Oishi, Masataka,Oshima, Masato,Suzuki, Hiroharu
, p. 6634 - 6654 (2014)
Zr-Ir hydrido complexes with ansa-(cyclopentadienyl)(amide) as the supporting ligand in the zirconium fragment, e.g., (L1ZrR) (Cp*Ir)(μ-H)3 [L1 = Me2Si(η 5-C5Me4)(NtBu), R = Cl (5), Ph (7), Me (10), alkyl, and aryl] were designed, synthesized, and isolated as tractable early-late heterodinuclear complexes. Despite the presence of the three supporting hydride ligands, Zr-Ir distances in the crystal structures of 5, alkyl, and aryl complexes [2.74-2.76 A] were slightly longer than the sum of the element radii of Zr and Ir [2.719 A]. These hydrocarbyl complexes displayed the thermolytic C-H activation of a variety of aromatic compounds and several organometallic compounds. Also, the substrate scope and limitation in the Zr-Ir system were studied. The regiochemical outcomes during the C-H activation of pyridine derivatives and methoxyarenes suggested the in situ generation of a Lewis acidic active intermediate, i.e., (L1Zr) (Cp*IrH2) (III). The existence of III and relevant σ-complex intermediates {L1Zr(η2-R-H)} (Cp*IrH2) (IIR) (R = Me, Ph) in the ligand exchange was demonstrated by the direct isolation of a Et3PO-adduct of III (39b) from 7 and kinetic studies. The structure of the direct Zr-Ir bonds in IIPh, IIMe, III, and 39b were probed using computational studies. The unprecedented strong M-M′ interactions in the early-late heterobimetallic (ELHB) complexes have been proposed herein.
ON THE ABSOLUTE REACTIVITY OF ARYL CATIONS: SELECTIVITY TOWARD HALIDE IONS AS A FUNCTION OF VISCOSITY
Lorand, John P.
, p. 7337 - 7340 (1989)
The selectivities toward bromide and chloride ions observed in the dediazoniation of three arenediazonium salts are found to be independent of viscosity.It is inferred that the capture of aryl cations by these halide ions is diffusion controlled.
Photochemically Switching Diamidocarbene Spin States Leads to Reversible Büchner Ring Expansions
Perera, Tharushi A.,Reinheimer, Eric W.,Hudnall, Todd W.
, p. 14807 - 14814 (2017)
The discovery of thermal and photochemical control by Woodward and Hoffmann revolutionized how we understand chemical reactivity. Similarly, we now describe the first example of a carbene that exhibits differing thermal and photochemical reactivity. When a singlet ground-state N,N'-diamidocarbene 1 was photolyzed at 380 nm, excitation to a triplet state was observed. The triplet-state electronic structure was characteristic of the expected biradical σ1pπ1 spin configuration according to a combination of spectroscopic and computational methods. Surprisingly, the triplet state of 1 was found to engage a series of arenes in thermally reversible Büchner ring expansion reactions, marking the first examples where both cyclopropanation and ring expansion of arenes were rendered reversible. Not only are these photochemical reactions different from the known thermal chemistry of 1, but the reversibility enabled us to perform the first examples of photochemically induced arene exchange/expansion reactions at a single carbon center.
Hydroxyl radical induced reactions in aqueous solutions of halogenated benzenes: Effect of electronegativity of halogen
Mohan, Hari,Mittal, Jai P.
, p. 599 - 607 (2002)
The .OH radicals, generated by radiolysis, are found to react only in acidic conditions with halogenated benzenes by an electron transfer mechanism. The concentration of acid, at which solute radical cation of halogenated benzenes appear, is observed to depend strongly on the nature and number of halogen atoms in halogenated benzenes. A linear increase in the acid concentration required for solute radical cation formation is observed with electronegativity of halogen.
REDUCTION BY A MODEL OF NAD(P)H. 42. DIRECT EVIDENCE FOR ONE ELECTRON TRANSFER MECHANISM IN THE REDUCTION OF ARENEDIAZONIUM SALTS.
Yasui, Shinro,Nakamura, Kaoru,Ohno, Atsuyoshi
, p. 3331 - 3334 (1983)
Arenediazonium salts are reduced by an NAD(P)H- model in methanol at room temperature to afford the corresponding reduction product, ArH.The reaction proceeds partially with a radical-chain mechanism involving initial one electron transfer from the NAD(P)H-model to the diazonium salt.
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Ainley,Challenger
, p. 2171,2176 (1930)
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Bromination of Deactivated Aromatics Using Potassium Bromate
Harrison, J.J.,Pellegrini, J.P.,Selwitz, C.M.
, p. 2169 - 2171 (1981)
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Kupchik, E. J.,Lanigan, T.
, p. 3661 - 3665 (1962)
Properties of PTFE tape as a semipermeable membrane in fluorous reactions
Parsons, Brendon A.,Smith, Olivia Lin,Chae, Myeong,Dragojlovic, Veljko
, p. 980 - 993 (2015)
In a PTFE tape phase-vanishing reaction (PV-PTFE), a delivery tube sealed with PTFE tape is inserted into a vessel which contains the substrate. The reagent diffuses across the PTFE tape barrier into the reaction vessel. PTFE co-polymer films have been found to exhibit selective permeability towards organic compounds, which was affected by the presence of solvents. In this study, we attempted to establish general trends of permeability of PTFE tape to different compounds and to better describe the process of solvent transport in PV-PTFE bromination reactions. Though PTFE tape has been reported as impermeable to some compounds, such as dimethyl phthalate, solvent adsorption to the tape altered its permeability and allowed diffusion through channels of solvent within the PTFE tape. In this case, the solvent-filled pores of the PTFE tape are chemically more akin to the adsorbed solvent rather than to the PTFE fluorous structure. The solvent uptake effect, which was frequently observed in the course of PV-PTFE reactions, can be related to the surface tension of the solvent and the polarity of the solvent relative to the reagent. The lack of pores in bulk PTFE prevents solvents from altering its permeability and, therefore, bulk PTFE is impermeable to most solvents and reagents. However, bromine, which is soluble in liquid fluorous media, diffused through the bulk PTFE. A better understanding of the PTFE phase barrier will make it possible to further optimize the PV-PTFE reaction design.
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Leicester
, p. 619 (1938)
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Photochemical Decomposition of Dibenzoyl Peroxide and Phenyl Benzoate in Solid KBr Matrix
Owen, David J.,O'Donnell, Jennifer,Schutt, Wendy,Morrow, Jeffrey,Li, Yuzhuo
, p. 6203 - 6207 (1993)
Physical and photochemical properties of dibenzoyl peroxide (DBPO) and phenyl benzoate (PB) in a solid KBr matrix were investigated.The photoinduced decompositions of DBPO and PB were monitored with infrared spectroscopy and HPLC.The organic molecules at different locations in the matrix contribute to the overall IR absorption differently.Therefore, they are affected differently during a photochemical decomposition.The bromide ions in the matrix intercept some of the radical intermediates in the decomposition of DBPO but have no influence on the radical pair in the rearrangement of phenyl benzoate.
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Kohn,Mueller
, p. 407 (1909)
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Noncatalytic bromination of benzene: A combined computational and experimental study
Shernyukov, Andrey V.,Genaev, Alexander M.,Salnikov, George E.,Rzepa, Henry S.,Shubin, Vyacheslav G.
, p. 210 - 225 (2016)
The noncatalytic bromination of benzene is shown experimentally to require high 5-14 M concentrations of bromine to proceed at ambient temperatures to form predominantly bromobenzene, along with detectable (6-benzene of 0.97 ± 0.03 at 298 K. These results are rationalized using computed transition states models at the B3LYP+D3/6-311++G(2d,2p) level with an essential continuum solvent field for benzene applied. The model with the lowest predicted activation free energies agrees with the high experimental kinetic order in bromine and involves formation of an ionic, concerted, and asynchronous transition state with a Br8 cluster resembling the structure of the known Br9-. This cluster plays three roles; as a Br+ donor, as a proton base, and as a stabilizing arm forming weak interactions with two adjacent benzene C-H hydrogens, these aspects together combining to overcome the lack of reactivity of benzene induced by its aromaticity. The computed inverse kinetic isotope effect of 0.95 agrees with experiment, and arises because C-Br bond formation is essentially complete, whereas C-H cleavage has not yet commenced. The computed free energy barriers for the reaction with 4Br2 and 5Br2 for a standard state of 14.3 M in bromine are reasonable for an ambient temperature reaction, unlike previously reported theoretical models involving only one or two bromines.
Formation and Reactivity of the Radical Cation of Bromobenzene in Aqueous Solution: A Pulse Radiolysis Study
Mohan, Hari,Mittal, Jai P.
, p. 6519 - 6524 (1995)
A transient optical absorption band (λmax=325 nm) is formed upon reaction of . OH radical with bromobenzene in neutral aqueous solution and is assigned to the OH adduct.In strongly acidic solution (HClO4 > 3 mol dm3), the OH adduct undergoes H+-catalyzed dehydroxylation to form the bromobenzene radical cation.This radical cation absorbs at 550 nm and at 270-310 nm.Even at this high H+ concentration, only a fraction of the OH adduct is converted to the radical cation.SO4.- reacts with bromobenzene to form the hydroxycyclohexadienyl radical (λmax=325 nm) and the phenoxyl radical (λmax=400 nm).The bromobenzene radical cation is also observed in irradiated 1,2-dichloroethane solutions.C6H5Br.+ is a strong one-electron oxidant and oxidizes Br-, SCN-, and organic sulfides with high rate constants.C6H5Br.+ undergoes electron transfer reaction with Cl- to establish an equilibrium, from which a reduction potential value for C6H5Br.+/C6H5Br was determined to be 2.31+/-0.15 V versus NHE.
Radical Rearrangements of Bicyclohexane: Homolytic Substitution of a Cyclobutane Ring
Walton, John C.
, p. 1252 - 1254 (1987)
Bromine atoms react with bicyclohexane in an SH2 reaction at the bridgehead carbon atoms; the bicyclohex-2-yl radical rearranges by β-scission of the inter-ring bond.
Reactivity of alkali and alkaline earth metal tetrafluorobromates towards aromatic compounds and pyridine
Sobolev, Vasily I.,Filimonov, Victor D.,Ostvald, Roman V.,Radchenko, Vyacheslav B.,Zherin, Ivan I.
, p. 120 - 123 (2016)
The bromination activity of tetrafluorobromates of alkali and alkali-earth metals increases in the order KBrF4, CsBrF4, RbBrF4and Ba(BrF4)2. The most active tetrafluorobromate—Ba(BrF4)2is able to selectively brominate the deactivated aromatic compounds nitrobenzene and 4-nitrotoluene, but not the activated compounds benzene and toluene. In all cases bromination of methyl groups of methylbenzenes does not occur. Ba(BrF4)2forms the known complex C6H5N·BrF3when reacted with pyridine. Due to dilution by inert BaF2, this pyridine-based complex is air stable and can be considered as safer and more convenient reagent in comparison with the original fluorobromates; it can selectively brominate benzene and toluene in contrast with tetrafluorobromates.
Ogata et al.
, p. 960 (1964)
Radical Hydrodehalogenation of Aryl Halides with H2 Catalyzed by a Phenanthroline-Based PNNP Cobalt(I) Complex
Iizuka, Kosuke,Ishizaka, Yusuke,Jheng, Nai-Yuan,Minami, Yasunori,Naganawa, Yuki,Nakajima, Yumiko,Sekiguchi, Akira
, p. 2320 - 2329 (2022/02/16)
Radical hydrodehalogenation of aryl halides (Ar-X; X = Cl, Br, I) is achieved in the presence of atmospheric pressure H2 as a H-atom donor using a Co(I) catalyst bearing a phenanthroline-based PNNP ligand (2,9-bis((diphenylphosphanyl)methyl)-1,10-phenanthroline). The reaction proceeds under mild conditions (1 atm H2) and is applicable to aryl bromides and aryl chlorides with various functional groups. A mechanistic study revealed that the PNNP-Co complex underwent facile H-H cleavage and facilitated a H-atom transfer. This process is mediated by a long-range metal-ligand cooperation of the PNNP-Co system, which includes the dearomatization/aromatization sequence of the phenanthroline ligand backbone. A radical clock experiment demonstrated the Ar-X bond cleavage via a radical mechanism. Further kinetic study supported that the rate-determining step includes electron transfer from the Co center to the substrate, affording a radical pair ArX?- and an odd-electron metal-halide complex [Co(II) + ArX?-]? as a transition state.
The graphite-catalyzed: ipso -functionalization of arylboronic acids in an aqueous medium: metal-free access to phenols, anilines, nitroarenes, and haloarenes
Badgoti, Ranveer Singh,Dandia, Anshu,Parewa, Vijay,Rathore, Kuldeep S.,Saini, Pratibha,Sharma, Ruchi
, p. 18040 - 18049 (2021/05/29)
An efficient, metal-free, and sustainable strategy has been described for the ipso-functionalization of phenylboronic acids using air as an oxidant in an aqueous medium. A range of carbon materials has been tested as carbocatalysts. To our surprise, graphite was found to be the best catalyst in terms of the turnover frequency. A broad range of valuable substituted aromatic compounds, i.e., phenols, anilines, nitroarenes, and haloarenes, has been prepared via the functionalization of the C-B bond into C-N, C-O, and many other C-X bonds. The vital role of the aromatic π-conjugation system of graphite in this protocol has been established and was observed via numerous analytic techniques. The heterogeneous nature of graphite facilitates the high recyclability of the carbocatalyst. This effective and easy system provides a multipurpose approach for the production of valuable substituted aromatic compounds without using any metals, ligands, bases, or harsh oxidants.
