- Oxidative bromination of non-activated aromatic compounds with AlBr3/KNO3 mixture
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Bromination of non-activated aromatic compounds with reaction mixture containing KNO3 and AlBr3 was studied in liquid substrates and in solvent. Aluminium bromide has three different roles in this reaction mixture. First, it is a source of bromide ions, which are essential in oxidative bromination application. Second, it acts as a catalyst, and lastly, it forms acidic environment via its hydrolysis, which is necessary for enhancement of the oxidising properties of nitrate ions. It was shown that when changing the reaction conditions, different side reactions (like nitration or Friedel–Crafts type arylation) can occur. However, it is possible to guide the reaction path and receive the desired outcome by choosing the suitable reaction conditions. In addition, it was shown that there has to be water content in this reaction mixture as the bromine formation rate depends on it, while there exists an optimal volume of water, where bromine formation is the fastest.
- Rahu, Ida,J?rv, Jaak
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p. 1219 - 1227
(2019/11/13)
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- "naked" Lithium Cation: Strongly Activated Metal Cations Facilitated by Carborane Anions
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Experimental and spectroscopic studies revealed unprecedented reactivity of a "naked" lithium cation with very weakly coordinating anions, including carborane anions. The superactivated lithium cation has greatly enhanced Lewis acidic character and mediates various organic reactions such as carbonyl-ene reaction, NBS-bromination of unactivated aromatics, and Friedel-Crafts alkylation, which are not promoted by conventional lithium salts. Chemical robustness of the counteranion also plays an important role in the chemistry of the strongly activated lithium cation.
- Kitazawa, Yu,Takita, Ryo,Yoshida, Kengo,Muranaka, Atsuya,Matsubara, Seijiro,Uchiyama, Masanobu
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p. 1931 - 1935
(2017/02/26)
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- PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
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The present invention provides a process for the preparation of organic bromides, by a radical bromodecarboxylation of carboxylic acids with a bromoisocyanurate.
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Paragraph 00133
(2017/07/28)
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- Reactivity of alkali and alkaline earth metal tetrafluorobromates towards aromatic compounds and pyridine
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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.
- Sobolev, Vasily I.,Filimonov, Victor D.,Ostvald, Roman V.,Radchenko, Vyacheslav B.,Zherin, Ivan I.
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p. 120 - 123
(2016/11/17)
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- Substd. photoisomerization arom. compd. method
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Isomerizing substituted aromatic compounds (I), comprises carrying out isomerization in the presence of a salt melt, which contains a metal compound (II) and at least one metal compound (III). Isomerizing substituted aromatic compounds of formula (Ar1-R n) (I) or their mixtures, comprises carrying out isomerization in the presence of a salt melt, which contains a metal compound of formula ([M1][X1] m 1) (II) and at least one metal compound of formula ([M2][X2] m 2) (III). Ar1 : n-valent aryl radical; R : halo, alkyl, fluoroalkyl, aryl, alkyl-aryl or amino; M1 : Al, Ga, In, Cu, Fe, Co or Ni; X1, X2 : halo, preferably Cl or Br; M2, m2 : alkaline earth metal or alkali metal, where M2 is preferably Li, Na, or K; m1 : Al, Ga, In, Fe(III), Co, Ni or Cu(II); and n : >= 2, preferably 2.
- -
-
Paragraph 0068
(2017/01/02)
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- Tribromoisocyanuric acid in trifluoroacetic acid: An efficient system for smooth brominating of moderately deactivated arenes
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Moderately deactivated arenes are efficiently brominated by the reaction with tribromoisocyanuric acid (0.34 mol equiv) in trifluoroacetic acid at room temperature in 48-85% isolated yield. This medium avoids the polybromination of the substrate, observed in the same reaction performed in 98% H 2SO4. Georg Thieme Verlag Stuttgart · New York.
- De Almeida, Leonardo S.,De Mattos, Marcioc. S.,Esteves, Pierre M.
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p. 603 - 606
(2013/04/10)
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- Bromination of aromatic compounds using an Fe2O 3/zeolite catalyst
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The catalytic bromination of non-activated aromatic compounds has been achieved using an Fe2O3/zeolite catalyst system. FeBr 3 was identified as the catalytic species, formed in situ from HBr and Fe2O3. The catalyst was easy-to-handle and cost effective and could also be recycled. The reaction system was also amenable to the one-pot sequential bromination/C-C bond formation of benzene.
- Nishina, Yuta,Takami, Keishi
-
supporting information
p. 2380 - 2383
(2013/02/21)
-
- Synthesis of uniformly 13C-labeled polycyclic aromatic hydrocarbons
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Convergent synthetic pathways were devised for efficient synthesis of a series of uniformly 13C labeled polycyclic aromatic hydrocarbons de novo from U-13C-benzene and other simple commercially-available 13C-starting compounds. All target products were obtained in excellent yields, including the alternant PAH U-13C-naphthalene, U-13C-phenanthrene, U-13C-anthracene, U- 13C-benz[a]anthracene, U-13C-pyrene and the nonalternant PAH U-13C-fluoranthene.
- Zhang, Zhenfa,Sangaiah, Ramiah,Gold, Avram,Ball, Louise M.
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p. 5431 - 5435
(2011/09/14)
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- Efficient and complementary methods offering access to synthetically valuable 1,2-dibromobenzenes
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1,2-Dibromobenzenes are highly valuable precursors for various organic transformations, in particular, reactions based on the intermediate formation of benzynes. This report describes short sequences for the synthesis of various derivatives based on regioselective bromination, ortho-metalation, and halogen/metal permutations. 1,2-Dibromo-3-iodobenzene (2f), 1,2-dibromo-4- iodobenzene (4c), and 2,3-dibromo-1,4-diiodobenzene (5e) act as intermediates in these syntheses. Bromo-iodoarenes have been synthesized by short and regioselective bromination or iodination sequences that combine ortho-metalation, halo-desilylation, diazotation, or bromination reactions of anilines. These polyhalo derivatives were then used as key intermediates to access a wide range of functionalized 1,2-dibromobenzenes by chemoselective organometallic reactions. Copyright
- Diemer, Vincent,Leroux, Frederic R.,Colobert, Fracoise
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experimental part
p. 327 - 340
(2011/02/26)
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- Thallium(III) oxide as an oxidative reagent in organic chemistry
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Oxidative properties of thallium(III) oxide in various organic reactions were studied. Oxidative bromination of organic compounds in Tl2O 3-KBr-trifluoroacetic acid system was carried out. New synthetic method for preparation of diphenylthallium salts from phenylhydrazine and thallium(III) oxide was developed.
- Gun'kin
-
scheme or table
p. 451 - 454
(2010/08/04)
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- Route to prepare 4-bromo-1-oxypentafluorosulfanylbenzene
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A process for preparing bromo-1-oxypentafluorosulfanylbenzene is provided, the process including the step of brominating pentafluorosulfanyloxybenzene with a bromination agent to provide the bromo-1-oxypentafluorosulfanylbenzene. The process is more effective than prior art processes for preparing such compounds.
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Page/Page column 4
(2008/06/13)
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- 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.
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- N-halosuccinimide/BF3-H2O, efficient electrophilic halogenating systems for aromatics
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N-Halosuccinimides (NXS, 1) are efficiently activated in trifluoromethanesulfonic acid and BF3-H2O, allowing the halogenations of deactivated aromatics. Because BF3-H2O is more economic, easy to prepare, nonoxidizing, and offers sufficiently high acidity (-H0 ≈ 12, only slightly lower than that of trifluoromethanesulfonic acid), an efficient new electrophilic reagent combination of NXS/BF3-H2O has been developed. DFT calculations at the B3LYP/6-311++G**//B3LYP/6-31G* level suggest that protonated N-halosuccinimides undergo further protosolvation at higher acidities to reactive superelectrophilic species capable either in the transfer of X+ from the protonated forms of NXS to the aromatic substrate or in forming a highly reactive and solvated X+ which would readily react with the aromatic substrates. Structural aspects of the BF 3-H2O complex have also been investigated.
- Prakash, G. K. Surya,Mathew, Thomas,Hoole, Dushyanthi,Esteves, Pierre M.,Wang, Qi,Rasul, Golam,Olah, George A.
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p. 15770 - 15776
(2007/10/03)
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- Pyridinium dichlorobromate: A new stable brominating agent for aromatic compounds
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Pyridinium dichlorobromate (PyHBrCl2, 1) is a new example of iminium-trihalide complexes. The compound is prepared from pyridine and chlorine in the presence of aqueous hydrogen bromide. The crystalline trihalide is quite stable and acts as a safe source of positive bromine. It shows a remarkable reactivity towards aromatic compounds compared with other bromine complexes. It is also considered as a potential source for bromine chloride BrCl.
- Muathen, Hussni A.
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p. 169 - 171
(2007/10/03)
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- Efficient method for the preparation of aromatic bromides and iodides by ferrocenium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate-catalyzed halogenation with bromine and iodine monochloride
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Direct iodination and bromination of various aromatic compounds with 1.1-2.0 molar amounts of iodine monochloride (ICl) and 1.1-3.0 molar amounts of bromine proceeded smoothly to afford the corresponding aromatic iodides and bromides, respectively, in good to excellent yields by using 0.05 molar amount of ferrocenium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, Cp2FeB[3,5-(CF3)2C6H 3]4 (1), in the presence of ZnO. Iodination of toluene in the co-existence of 0.5 molar amount of DDQ also proceeded to give iodotoluenes in high yield.
- Kitagawa, Hideo,Shibata, Tsuyoshi,Matsuo, Jun-Ichi,Mukaiyama, Teruaki
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p. 339 - 345
(2007/10/03)
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- The Activation of O2 at Ruthenium Complexes: Catalytic Chlorination of Unsaturated Organic Substrates within the System O2/HCl/H2O
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A solution of RuCl3 in concentrated hydrochloric acid is capable of chlorinating aromatic compounds catalytically, if O2 is present as the oxidizing agent (brominations can be achieved in hydrobromic acid). When olefins are chosen as substrates, two Cl atoms are added to the double bond in an anti fashion, while hydrochlorination products are formed simultaneously. According to the products observed in both types of reactions for various substrates in this 3-phase system, the halogenations proceed via electrophilic pathways.
- Limberg, Christian,Teles, Joaquim Henrique
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p. 447 - 449
(2007/10/03)
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- Halodediazoniations of dry arenediazonium o-benzenedisulfonimides in the presence or absence of an electron transfer catalyst. Easy general procedures to prepare aryl chlorides, bromides, and iodides
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The paper reports the results of a wide study aimed at preparing aryl chlorides 3 (19 examples), bromides 4 (19 examples), and iodides 5 (9 examples) by halodediazoniation of dry arenediazonium o-benzenedisulfonimides 1 with tetraalkylammonium halides 2. The reactions were carried out in anhydrous acetonitrile at room temperature (~20 °C) in the presence of copper powder and at 60 °C or room temperature without the catalyst. In optimal conditions the yields were from good to excellent (60 reactions, 61- 94% yield), with only a few exceptions (8 reactions, 51-55% yield). A good amount of the o-benzenedisulfonimide (7) was always recovered from the reactions and could then be reused to prepare salts 1. An interesting aspect of this research is the surprising role of the anion of o- benzenedisulfonimide (9) as an electron transfer agent.
- Barbero,Degani,Dughera,Fochi
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p. 3448 - 3453
(2007/10/03)
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- The use of supported zinc bromide for the fast and selective bromination of aromatic substrates
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Zinc bromide supported on acid activated montmorillonite (K-10) or mesoporous silica (100 A) is a fast, selective catalyst for the para-bromination of activated and mildly deactivated aromatic substrates. The optimum loading of zinc bromide on K-10 is 1.25 mmol/g and 1.75 mmol/g on the higher surface area silica (100 A). Thermal activation of these catalysts at 200 °C results in optimum activity and selectivity. Also, system optimisation has allowed harmful chlorinated solvents to be replaced by less damaging hydrocarbon solvents.
- Ross, Joanne C.,Clark, James H.,Macquarrie, Duncan J.,Barlow, Simon J.,Bastock, Tony W.
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p. 245 - 249
(2013/09/08)
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- Environmentally friendly catalysis using supported reagents: The fast and selective bromination of aromatic substrates using supported zinc bromide
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Zinc bromide supported on mesoporous silica or acid-activated montmorillonite is a fast, efficient, selective and reusable catalyst for the para-bromination of activated and moderately deactivated aromatic substrates.
- Clark, James H.,Ross, Joanne C.,Macquarrie, Duncan J.,Barlow, Simon J.,Bastock, Tony W.
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p. 1203 - 1204
(2007/10/03)
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- Hydrodehalogenation of Polyhalogenated Aromatics under Multiphase Conditions with H2 and Metal Catalyst: Kinetics and Selectivity
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Aryl halides have been catalytically hydrodehalogenated by bubbling H2 at atmospheric pressure into a biphasic system constituted by an organic solvent and an aqueous solution (aq., KOH 50percent), in the presence of a metal catalyst (Pd/C or Ranay-Ni) and a quaternary onium salt as a phase-transfer (PT) catalyst.Under such new conditions, the hydrodehalogenation of aromatic halides, even of sterically hindered ones, proceeds quickly at low temperatures (20-50 deg C) and affords the corresponding non-halogenated hydrocarbons in substantially quantitative yields.The addition of a quaternary onium salt to the multiphase system may induce remarkable effects both in the enhancement of the reduction rate and in the regio- and chemo-selectivity of the reaction.For instance, when Aliquat 336 (tricaprylmethylammonium chloride) is used, the isomeric chloroethylbenzenes react 50 times faster, para-dichlorobenzene is reduced slower than the ortho isomer, and halogenated aromatic ketones can be effectively dehalogenated, without any reduction of the carbonyl group.Under the same reaction conditions, the addition of an onium salt is required for the Raney-Ni catalyst to become effective as a hydrodehalogenation catalyst.
- Marques, Carlos Alberto,Selva, Maurizio,Tundo, Pietro
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p. 317 - 328
(2007/10/03)
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- Quaternary ammonium compounds having muscle relaxation activity
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A quaternary ammonium having a muscle relaxation activity compound represented by the formula (I): STR1 wherein R1 represents a methylene, a lower alkylenoxy, a lower alkenylene, a lower alkynylene, --CO--, --COO--, a lower alkylene carbonyloxy, --CH(OR5)--, a lower alkylenecarbonyl, a hydroxy lower alkylene, --O--, --S--, --SO--, or --SO2 --; R2 represents a hydrogen atom, a hydroxy lower alkyl, an aldehyde, a lower alkyl carbonyl, --NO2, or --NHR6 ; R3 represents a hydrogen atom of a group --R1 --(CH2)a --[CH(CH2 A)--CH2 ]b --A; R4 represents an anion; R5 and R6 represent a hydrogen atom or a acetyl; A represents a quaternary ammonium group; a represents an integer of 1 to 8; b represents 0 or 1; m represents an integer of 1 to 4; and (Z) represents a trivalent benzene ring, a trivalent naphthalene ring, a trivalent diphenyl or a trivalent ethane radical.
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- CATALYTIC AND STOICHIOMETRIC BROMINATION OF AROMATIC COMPOUNDS IN AQUEOUS TRIFLUOROACETIC ACID IN THE PRESENCE OF NITROGEN-CONTAINING OXIDIZING AGENTS
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The mono- and polybromination of benzene, halogenobenzenes, toluene, p-xylene, anisole, biphenyl, benzotrifluoride, benzoic acid, p-nitro- and p-carboxytoluene, p-methoxybenzonitrile, tetralin, and naphtalene were studied in trifluoroacetic acid and its aqueous solutions in systems containing stoichiometric amounts of bromine or alkali-metal bromide and stoichiometric or catalytic (in the presence of oxygen or air) amounts of nitrogen-containing oxidizing agent (nitrogen(IV) oxide, alkali-metal nitrate or nitrite).It is suggested that the brominating agent under the investigated conditions is nitryl bromide NO2Br.Under the conditions of catalytic bromination anthracene is oxidized to anthraquinone with a preparative yield.
- Cheprakov, A. V.,Makhon'kov, D. I.,Rodkin, M. A.,Beletskaya, I. P.
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p. 217 - 223
(2007/10/02)
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- OXIDATION BY METAL SALTS. OXIDATIVE HALOGENATION OF BENZENE AND HALOBENZENES PROMOTED BY Co(III) AND Mn(III) ACETATES IN TRIFLUOROACETIC ACID AND ITS AQUEOUS SOLUTIONS
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A study was carried out on the oxidation of benzene and halobenzenes by Co(III) and Mn(III) acetates in the presence of alkali metal chlorides and bromides in CF3CO2H and its aqueous solutions (10-33 vol. percent H2O).The optimal water content in the solution is a function both of the nature of the metal oxidizing agent and the aromatic substrate.The reaction presumably proceeds through the formation of an aromatic radical-cation which then reacts with the halide anion.The oxidative chlorination of bromobenzene is complicated by ipso substitution and bromine redistribution.Phenyl iodosodichloride may be isolated in preparative yield in the chlorination of iodobenzene.In other cases, variation of the reaction conditions may give high yields of the corresponding chlorine and bromine derivatives.The feasibility of polychlorination was studied.Possible reaction mechanisms were considered.
- Makhon'kov, D. I.,Cheprakov, A. V.,Beletskaya, I. P.
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p. 609 - 615
(2007/10/02)
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- Photochemical Bromination of Simple Arenes
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Photochemical bromination of benzene, fluorobenzene, chlorobenzene, t-butylbenzene, α,α,α-trifluorotoluene, and (in tetrachloromethane) biphenyl and naphthalene gives substitution products and adducts such as 1,2,3,4,5,6-hexabromocyclohexane (1).The decomposition of (1) and of the analogous chlorobenzene adduct (3) under photochemical conditions gives the parent arene, the monobrominated halogenobenzene, and bromine which may be scavenged by toluene to give benzyl bromide or by benzene to give bromobenzene and dibromobenzenes.Addition is a kinetically controlled process, so that the mechanism of formation of these aryl bromides must be largely through the reversible formation of these adducts.This is consistent with the unusual orientation of apparent attack by bromine upon the arene substrates, since the relative amounts of the isomeric aryl bromides is a consequence of the relative stabilities and ease of elimination of HBr and Br2 from a family of adducts. The range of isomer distribution found within the reaction of each arene with bromine is consistent with two competing processes involved in the formation of the aryl bromides; one of these might by the direct homolytic substitution by bromine atoms upon the arene.
- Bolton, Roger,Bhangar, Muhammad Iqbal,Williams, Gareth H.
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p. 893 - 896
(2007/10/02)
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- Bromination of Azobenzenes by Acidified Hypobromus Acid; Orientation, Reactivity and Mechanism
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The rate of bromination of azobenzene by acidified hypobromousacid has been measured and compared with those of benzene, toluene, and bromobenzene under the same conditions.Determination of o/m/p ratios for attack on azobenzene show that the rate of attack at the meta position is much lower than expected on the basis of the Hammett ?m value for the phenylazo substituent.Abnormally low amounts of meta isomer were also observed for the case of bromobenzene, but not toulene.The rates of bromination of two monosubstituted azobenzenes (m-Br, and p-F) were alsodetermined and comparedwith that of azobenzene.
- Christoforou, Demetrius,Happer, Duncan A. R.,Munro, Murray H. G.
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p. 741 - 749
(2007/10/02)
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- Process for preparation of acetylene terminated sulfones, oligomers and precursors therefor
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Acetylene terminated sulfones and oligomers thereof are prepared by reacting a sulfonyldiphenol with a material selected from the group consisting of a meta-dibromobenzene, a para-dibromobenzene and mixtures thereof in the presence of a potassium base to form a bis-bromophenoxydiphenyl sulfone, which is reacted with a substituted terminal acetylene compound containing at least three carbon atoms and an hydroxy group on the carbon atom adjacent to the acetylene group to form an hydroxy-acetylene terminated phenoxydiphenyl sulfone, which is then subjected to base catalyzed cleavage to form the desired acetylene terminated sulfones and oligomers. An hydroxy-arylacetylene terminated sulfone is prepared by reacting a sulfonyldiphenyl with a material selected from the group consisting of meta-dibromobenzene para-dibromobenzene and mixtures thereof in the presence of a sodium base. The resulting hydroxyphenylbromophenoxyphenyl sulfone can be: (1) reacted with a substituted terminal acetylene compound to form an hydroxy-arylacetylene terminated sulfone which in turn can be reacted with a dinitrofluorobenzene to form a dinitro-acetylene terminated sulfone which in turn can be reacted with sodium dithionite and sodium hydroxide to form a diaminoacetylene terminated sulfone; (2) reacted with a dibromobenzene to form a bis-bromophenoxydiphenyl sulfone; or (3) reacted with a bis-bromophenoxydiphenyl sulfone to form an oligomeric bromophenoxydiphenyl sulfone, which can be used to form an oligomeric actylene terminated sulfone. Metal contaminants, such as palladium and copper, used in the preparation of the acetylene terminated sulfones are removed by admixing the metal contaminated sulfone with a hydrogen halide and then contacting the admixture with an amino compound to complex the metal contaminant.
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- Removal of stannic chloride
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Stannic chloride is removed from organic solvent-based waste streams by precipitating the salt as a dimethyl sulfoxide complex.
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- Sulfonation of aromatic compounds in the presence of solvents
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A process for the sulfonation of aromatic compounds wherein an aromatic substance consisting of one or more aromatic compounds susceptible to the action of sulfur trioxide is formed into a reactant by admixture with one or more organic liquids, substantially inert to sulfur trioxide under the conditions of the process, which reactant is brought to boiling at a temperature not greater than 100° C under a pressure of from 0.1 mm Hg to atmospheric pressure, gaseous sulfur trioxide is introduced thereinto thereby causing it to continue to boil, the component or components of the reactant thus volatilized is or are reconverted to liquid in a heat-exchanger and recycled to the reaction chamber, and the pressure in the reaction chamber and the rate at which the gaseous sulfur trioxide is introduced into the reactant are controlled so as to ensure that there is always present in the reaction chamber an amount of volatilizable matter exceeding that amount volatilizable by the heat of reaction of the aromatic substance present in the reaction chamber with the gaseous sulfur trioxide in contact with said aromatic substance and that the temperature of the reaction mixture is a temperature of 100° C or below.
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