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Direct bromodeboronation of arylboronic acids with CuBr2 in water
An efficient and practical method has been developed for the preparation of aryl bromides via the direct bromodeboronation of arylboronic acids with CuBr2 in water. This strategy provides several advantages, such as being ligand-free, base-free, high yielding, and functional group tolerant.
Tang, Yan-Ling,Xia, Xian-Song,Gao, Jin-Chun,Li, Min-Xin,Mao, Ze-Wei
supporting information

(2021/01/05)

The graphite-catalyzed: ipso -functionalization of arylboronic acids in an aqueous medium: metal-free access to phenols, anilines, nitroarenes, and haloarenes
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.
Badgoti, Ranveer Singh,Dandia, Anshu,Parewa, Vijay,Rathore, Kuldeep S.,Saini, Pratibha,Sharma, Ruchi
p. 18040 - 18049
(2021/05/29)

Dehydroxyalkylative halogenation of C(aryl)-C bonds of aryl alcohols
We herein report Cu mediated side-directed dehydroxyalkylative halogenation of aryl alcohols. C(aryl)-C bonds of aryl alcohols were effectively cleaved, affording the corresponding aryl chlorides, bromides and iodides in excellent yields. Aryl alcohols could serve as both aromatic electrophilic and radical synthetic equivalents during the reaction.
Liu, Mingyang,Zhang, Zhanrong,Liu, Huizhen,Wu, Tianbin,Han, Buxing
supporting information
p. 7120 - 7123
(2020/07/14)

Metal- and base-free synthesis of aryl bromides from arylhydrazines
An efficient method was developed to synthesize brominated aromatic compounds from arylhydrazine hydrochlorides by using BBr3 in DMSO/CPME (cyclopentyl methyl ether) under air at 80 °C for 1 h without the use of bases or metal catalysts. In particular, this method could be carried out satisfactorily using electron-withdrawing groups to afford aryl bromides in a moderate to excellent yields.
Phuc Tran, Dat,Nomoto, Akihiro,Mita, Soichiro,Dong, Chun-ping,Kodama, Shintaro,Mizuno, Takumi,Ogawa, Akiya
supporting information

(2020/05/08)

Amplification of Trichloroisocyanuric Acid (TCCA) Reactivity for Chlorination of Arenes and Heteroarenes via Catalytic Organic Dye Activation
Heteroarenes and arenes that contain electron-withdrawing groups are chlorinated in good to excellent yields (scalable to gram scale) using trichloroisocyanuric acid (TCCA) and catalytic Brilliant Green (BG). Visible-light activation of BG serves to amplify the electrophilic nature of TCCA, providing a mild alternative approach to acid-promoted chlorination of deactivated (hetero)aromatic substrates. The utility of the TCCA/BG system is demonstrated through comparison to other chlorinating reagents and by the chlorination of pharmaceuticals including caffeine, lidocaine, and phenazone.
Rogers, David A.,Bensalah, Adam T.,Espinosa, Alvaro Tomas,Hoerr, John L.,Refai, Fares H.,Pitzel, Amy K.,Alvarado, Juan J.,Lamar, Angus A.
supporting information
p. 4229 - 4233
(2019/06/17)

PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
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 00139; 00143

(2017/07/28)

PROCESS FOR THE PREPARATION OF ORGANIC HALIDES
The present invention provides a halo-de-carboxylation process for the preparation of organic chlorides, organic bromides and mixtures thereof, from their corresponding carboxylic acids, using a chlorinating agent selected from trichloroisocyanuric acid (TCCA), dichloroisocyanuric acid (DCCA), or combination thereof, and a brominating agent.
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Paragraph 00143

(2017/08/01)

Eco-compatible zeolite-catalysed continuous halogenation of aromatics
A completely eco-compatible halogenation reaction of arenes has been developed allowing high conversions (>95%) of iodobenzene with nearly 100 kg iodobenzene converted per kgcat in one day. Several solid acids, zeolites being the most promising, have been successfully tested in the chlorination reaction of iodobenzene by using trichloroisocyanuric acid (TCCA), a green chlorination agent. H-?BEA zeolites were found to be the most active catalysts for this model halogenation reaction. A strong structure-activity relationship could be established by thorough characterisation (SEM, BET, XRD, FTIR) of various synthetic zeolites. Indeed, nano-sized ?BEA zeolites and more specifically nanosponge-like ?BEA crystals exhibited the highest catalytic performance with a conversion up to 100% and a selectivity toward monochlorinated products up to 98%. Finally, the gained knowledge was applied to set-up an eco-compatible continuous flow halogenation process of different aromatics catalysed by H-?BEA zeolites.
Losch,Kolb,Astafan,Daou,Pinard,Pale,Louis
p. 4714 - 4724
(2016/09/04)

A paradichlorbenzene dichloroethane pharmaceutical intermediates method for synthesis of O-chloro-bromobenzene (by machine translation)
A paradichlorbenzene dichloroethane pharmaceutical intermediates method for synthesis of O-chloro-bromobenzene, comprising the following steps : (i) in the reaction container by adding O-aminochlorobenzene 0.8mol, aqueous solution 100 ml, control the stirring speed in the 300-500rpm, sodium bromide solution to 300 ml, control the temperature of the solution for 6-9°C, potassium sulfite dropping 0.8mol soluble in 100-120ml in aqueous solution, keeping the temperature of the solution after the adding the 35-40°C, potassium iodide test for determining the end point of the reaction, the diazonium salt is generated (3); the stannous chloride (ii) 0.12mol, the mass fraction is 50-70% sodium bromide solution of 200-300ml mixed in the reaction vessel, heating the solution temperature to 90-92°C, dropping step (i) generating the diazotizing solution, after adding water vapor distillation, separating the organic layer, the aqueous layer is extracted with a solvent a certain number of times, the merger with the extracted oil, used for quality score for sequentially 30-40% phosphoric acid washing, and washing solution, salt solution washing, dehydrating agent dehydration, vacuum distillation to extracting distilled, collecting 180-185 °C fraction, O-chloro-bromobenzene may be colorless transparent product. (by machine translation)
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Paragraph 0018; 0019; 0020

(2016/11/17)

Substd. photoisomerization arom. compd. method
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.
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Paragraph 0066

(2017/01/02)

Isomerisation of 1,4-dichlorobenzene using highly acidic alkali chloroaluminate melts
The isomerisation reaction of 1,4-dichlorobenzene leading to the thermodynamically favoured and technically desired 1,3-dichlorobenzene has been studied comparing highly acidic chloroaluminate melts with organic imidazolium and alkali metal ions. Interestingly, the inorganic melts show much higher reactivity and full recyclability if small AlCl3 losses are compensated and the reaction is carried out under slight HCl pressure. This journal is
Messner,Schulz,Taccardi,Kuhlmann, Sven,Wasserscheid
supporting information
p. 11705 - 11708
(2015/05/20)

Tribromoisocyanuric acid in trifluoroacetic acid: An efficient system for smooth brominating of moderately deactivated arenes
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.
p. 603 - 606
(2013/04/10)

A new recoverable Au(III) catalyst supported on magnetic polymer nanocomposite for aromatic bromination
This Letter presents a facile alternative synthesis of a recoverable Au(III) catalyst supported on Fe3O4@SiO 2～MPS grafted by poly(N-vinyl-2-pyrrolidone) (PVP). The solid magnetic support was prepared by anchoring 3-methacryloxypropyltrimethoxysilane (MPS) onto the Fe3O4@SiO2 surfaces followed by free radical polymerization with N-vinyl-2-pyrrolidone. Au(III) was immobilized onto the magnetic support in aqueous media to afford Au(III)/Fe 3O4@SiO2～PVP (catalyst 1). Catalyst 1 was characterized by FT-IR, TEM, VSM, TGA, XRD, and ICP-AES. The amount of Au in catalyst 1 was measured to be 0.64 wt % by ICP-AES. This newly prepared catalyst can catalyze the aromatic bromination reaction with comparable activity as homogeneous AuCl3. Moreover, the supported catalyst is easy to recover and can be used in four cycles without apparent loss of activity.
Li, Bai,Gao, Linfeng,Bian, Fengling,Yu, Wei
supporting information
p. 1063 - 1066
(2013/04/10)

Halogen exchange via a halogenation of diaryliodonium salts with cuprous halide
An efficient halogenation reaction has been developed with diaryliodonium salts and cuprous halides. Various diaryliodonium salts 1 could perform the reaction with readily available CuBr or CuCl in CH3CN at 80°C, assembling bromoarenes or chloroarenes in up to 92% yields. This provides us a method for the transformation from iodoarenes to other haloarenes.
Li, Jian,Liu, Li,Ding, Dong,Sun, Jiang-Tao
p. 541 - 548
(2014/01/06)

Tetraflic acid (1,1,2,2-Tetrafluoroethanesulfonic acid, HC 2F4SO3H) and gallium tetraflate as effective catalysts in organic synthesis
Tetraflic acid offers ample acidity for various organic reactions that require high acidity. Its gallium(III) salt is an efficient catalyst under mild condtions for synthetic transformations such as the ketonic Strecker reaction for the synthesis of fluorinated α-amino nitriles and condensation- cyclzation reactions using suitable fluoro ketones and 1,2-disubstituted benzenes for the direct preparation of 5-membered or 6-membered fluorinated heterocycles. Copyright
Prakash, G. K. Surya,Mathew, Thomas,Panja, Chiradeep,Kulkarni, Aditya,Olah, George A.,Harmer, Mark A.
p. 2163 - 2171
(2012/11/07)

Bromination of aromatic compounds using an Fe2O 3/zeolite catalyst
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)

Thallium(III) oxide as an oxidative reagent in organic chemistry
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)

Gold-catalyzed halogenation of aromatics by N-halosuccinimides
(Chemical Equation Presented) Golden bromination: A highly efficient and mild AuCl3-catalyzed bromination of aromatic rings with Nbromosuccinimide (NBS) has been developed. This method works with a low catalyst loading (down to 0.01 mol %) and can be combined with transition metal catalyzed transformations to deliver various aryl products.
Mo, Fanyang,Yan, Jerry Mingtao,Qiu, Di,Li, Fei,Zhang, Yan,Wang, Jianbo
scheme or table
p. 2028 - 2032
(2010/06/17)

A novel synthesis of bromobenzenes using molecular bromine
Certain substituted bromobenzenes have been synthesized in acceptable yields using a novel Sandmeyer type reaction. The reactions are relatively quick and possibly proceed via a radical mechanism.
Oezkan, Hamdi,Disli, Ali,Yildirir, Yilmaz,Tuerker, Lemi
p. 2478 - 2483
(2008/03/13)

Regioselective halogen-metal exchange reaction of 3-substituted 1,2-dibromo arenes: The synthesis of 2-substituted 5-bromobenzoic acids
Regioselective halogen-metal exchange reactions using isopropylmagnesium chloride were carried out on 3-substituted 1,2-dibromo arenes. Eleven examples are given. Georg Thieme Verlag Stuttgart.
Menzel, Karsten,Dimichele, Lisa,Mills, Paul,Frantz, Doug E.,Nelson, Todd D.,Kress, Michael H.
p. 1948 - 1952
(2008/02/08)

Regioselective bromination of aromatic compounds with Br 2/SO2Cl2 over microporous catalysts
A new selective brominating system Br2/SO2Cl 2/zeolite, has been discovered. Partially cation-exchanged Ca 2+-Y zeolite efficiently catalyzes the selective para-bromination of neat chlorobenzene (CB) by Br2/SO2Cl2 affording a CB conversion of ～89% and a para-selectivity of ～97%. During the bromination reaction, SO2Cl2 oxidizes HBr, prevents its accumulation within the zeolite pores and yields a more active brominating species. The Ca2+-Y catalyst was found to be stable under the bromination conditions, and can easily be regenerated by calcination. The Br2/SO2Cl2/Ca2+-Y brominating system could be applicable to other activated aromatic compounds such as o-xylene, toluene and fluorobenzene.
Gnaim, Jallal M.,Sheldon, Roger A.
p. 4465 - 4468
(2007/10/03)

N-halosuccinimide/BF3-H2O, efficient electrophilic halogenating systems for aromatics
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.
p. 15770 - 15776
(2007/10/03)

Halogenation of Aromatic Compounds by N-chloro-, N-bromo-, and N-iodosuccinimide
An efficient and mild method for the halogenation of aromatic compounds using N-chloro-, N-bromo-, and N-iodosuccinimide in the presence of NH 4NO3 or FeCl3 in acetonitrile was developed.
Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Satsumabayashi, Koko,Horaguchi, Takaaki
p. 932 - 933
(2007/10/03)

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
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
p. 339 - 345
(2007/10/03)

CARBOXYLIC ACID DERIVATIVES AND DRUGS CONTAINING THE SAME
The present invention provides a novel carboxylic acid compound, a salt thereof or a hydrate of them useful as an insulin-resistant improver, and a medicament comprising the compound as an active ingredient. That is, the present invention provides a carboxylic acid compound represented by the following formula (I), a salt thereof, an ester thereof or a hydrate of them. In the formula, R1 represents hydrogen atom, hydroxyl group or a C1-6 alkyl group etc. which may have one or more substituents; L represents a single or double bond or a C1-6 alkylene group etc. which may have one or more substituents; M represents a single bond or a C1-6 alkylene group etc. which may have one or more substituents; T represents a single bond or a C1-3 alkylene group which may have one or more substituents; W represents carboxyl group or a group represented by the formula -CON(Rw1)Rw2 (wherein Rw1 and Rw2 are the same as or different from each other and each represents hydrogen atom, formyl group etc.) etc.; represents a single or double bond; X represents oxygen atom or a C2-6 alkenylene group etc. which may have one or more substituents; Y represents a C5-12 aromatic hydrocarbon group etc. which may have one or more substituents and which may have one or more heteroatoms; and ring Z represents a C5-6 aromatic hydrocarbon group which may have 0 to 4 substituents and which may have one or more heteroatoms.
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(2008/06/13)

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
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
p. 3448 - 3453
(2007/10/03)

The use of supported zinc bromide for the fast and selective bromination of aromatic substrates
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.
p. 245 - 249
(2013/09/08)

Environmentally friendly catalysis using supported reagents: The fast and selective bromination of aromatic substrates using supported zinc bromide
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.
p. 1203 - 1204
(2007/10/03)

ONE STEP CONVERSION OF ANILINES TO ARYL HALIDES USING SODIUM NITRITE AND HALOTRIMETHYLSILANE
Anilines were easily diazotized and efficiently converted to aryl halides in an one-pot reaction using sodium nitrite and halotrimethylsilane in carbon tetrachloride.Halotrimethylsilanes are used for both generating nitrosonium donor from sodium nitrite, and the halogen substitution of diazonium group.
Lee, Jong Gun,Cha, Hee Tae
p. 3167 - 3168
(2007/10/02)

OXIDATIVE CHLORINATION OF AROMATIC COMPOUNDS IN THE PRESENCE OF NITROGEN-CONTAINING OXIDIZING AGENTS
Mixture of the chlorides and nitrates of alkali metals in aqueous trifluoroacetic acid can be used for the selective oxidative chlorination of benzene, halogenobenzenes, toluene, and p-toluic acid with preparative yields.By variation of the water content of the solvent and the nitrate-chloride ratio it is possible to suppress the nitration side reaction.In the presence of oxygen or air alkali-metal nitrites can also be used as oxidizing agents in this process.The chlorinating agent in these systems is molecular chlorine, as confirmed by a comparative study of the reactions of two groups of potential chlorinating agents (nitrosyl chloride and nitryl chloride) under these conditions.The reactions of naphthalene and polymethylbenzenes with nitrosyl chloride in trifluoroacetic acid, leading to the products from chlorination and dehydrooligomerization of the aromatic substrates, were also studied.
Makhon'kov, D. I.,Cheprakov, A. V.,Rodkin, M. A.,Beletskaya, I. P.
p. 211 - 217
(2007/10/02)

CATALYTIC AND STOICHIOMETRIC BROMINATION OF AROMATIC COMPOUNDS IN AQUEOUS TRIFLUOROACETIC ACID IN THE PRESENCE OF NITROGEN-CONTAINING OXIDIZING AGENTS
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.
p. 217 - 223
(2007/10/02)

OXIDATIVE HALOGENATION OF AROMATIC COMPOUNDS IN THE Pb3O4-Hal--CF3CO2H SYSTEM
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Makhon'kov, D. I.,Cheprakov, A. V.,Rodkin, M. A.,Serguchev, Yu. A.,Davydova, V. G.,Beletskaya, I. P.
p. 2424 - 2426
(2007/10/02)

DECOMPOSITION OF (NiRR'L2) COMPLEXES INDUCED BY BROMINE OR ANODIC OXIDATION
A study has been made of the decomposition of the compounds t-(NiRR'L2) (L=PMe2Ph and PEt3; R=aryl or vinyl groups) and (Ni(mes)(o-tol)bipy) (mes=mesityl) oxidatively induced either by electrochemical means or by bromine.No organometallic compound of Ni(III) was isolated in the above reactions, but a pentacoordinate intermediate of Ni(III) is postulated.Breakdown takes place readily after the Ni(III) intermediate is formed.If the decomposition is induced is induced electrochemically, the intermediate decomposes giving only the coupling product R-R'.When bromine is used as the oxidizing agent, the Ni(III) intermediate is only formed if coordination to the central atom is allowed by the volume of the ligands.Thus, (Ni(C2Cl3)(mes)(PMe2Ph)2) dos not decompose at all, and only (Ni(C2Cl3(mesBr2)(PMe2Ph)2) is obtained.The intermediate ' Ni(III)RR'BrL2' undergoes reductive elimination to give R-R', RBr and R'Br.The formation of the products R-R'is increasingly favoured the greater the electronegativity of the organic ligands.The reductive elimination giving RBr takes place more readily the greater the electronegativity of the organic ligand R.The product of the reductive elimination reaction is 'Ni(I)Br', 'Ni(I)R', or 'Ni(I)R'', which in the presence of bromine give Ni(2+), (NiBr(RBr)L2), phosphonium salts, RBr, and R'Br.
Coronas, Juan M.,Muller, Guillermo,Rocamora, Mercedes
p. 227 - 236
(2007/10/02)

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
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.
p. 609 - 615
(2007/10/02)

OXIDATION BY THE SALTS OF METALS. VII. PLUMBATION AND OXIDATIVE SUBSTITUTION OF AROMATIC COMPOUNDS IN THE LEAD TETRAACETATE-LITHIUM CHLORIDE SYSTEM IN THE PRESENCE OF PERFLUORINATED CARBOXYLIC ACIDS
The oxidation of benzene and substituted benzenes PhX with electron-donating (X = CH3, OCH3) and electron-withdrawing (X = Hlg, CF3, NO2) substituents in the Pb(OAc)4-LiCl system was investigated in the presence of perfluorinated carboxylic acids RfCOOH (Rf = CF3, C6F13).The reaction leads to the plumbation, chlorination, and acyloxylation products.It was shown that the reactions take place through the formation of aryl derivatives of lead(IV) with the participation of mixed-ligand complexes of lead.The products from the plumbation of toluene (in C6F13COOH in the absence of lithium chloride) and benzotrifluoro were isolated.In trifluoroacetic acid these intermediates undergo intramolecular redox decomposition with ligand transfer.The halogenobenzenes and benzotrifluoride are oxidized selectively in the CF3COOH-Pb(IV)-LiCl system, giving the corresponding aryl chlorides with yields close to quantitative (80-90percent).
Serguchev, Yu. A.,Davydova, V. G.,Makhon'kov, D. I.,Beletskaya, I. P.
p. 1006 - 1011
(2007/10/02)

OXIDATIVE BROMINATION OF AROMATIC COMPOUNDS IN THE KBr-Pb(OAc)4-CF3CO2H SYSTEM
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Serguchev, Yu. A.,Davydova, V. G.,Makhon'kov, D. I.,Beletskaya, I. P.
p. 1550
(2007/10/02)

Highly para-Selective Mono-Chlorination of Aromatic Compounds Under Mild Conditions by t-Butyl Hypochlorite in the Presence of Zeolites
t-Butyl hypochlorite supported on H(1+), Na(1+) faujasite X (zeolite X) produces para-selective monochlorination of alkyl-, phenyl-, and halobenzenes under mild conditions; for example, chlorobenzene in acetonitrile (at 40 deg C) is chlorinated in high yield of isolated product (92percent) to give dichlorobenzene with an isomer ratio 97percent para/3percent ortho.
Smith, Keith,Butters, Michael,Nay, Barry
p. 1157 - 1158
(2007/10/02)

Photochemical Bromination of Simple Arenes
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.
p. 893 - 896
(2007/10/02)

Evidence for the Intermediacy of the Aryl Radical in the Sandmeyer Reaction
The competition between bromodediazoniation and chlorodediazoniation is exploited as a test of the occurrence of an aryl radical in the Sandmeyer reaction pathway.The use of five reducing agents, covering a wide range of redox ability, is shown not to influence the experimental kBr/kCl values.The intermediacy of a common species is consequently inferred and supported by independent generation of the phenyl radical by decomposition of benzoyl peroxide.Considerations on the rates of the ligand transfer processes are put forward.
Galli, Carlo
p. 1139 - 1142
(2007/10/02)

Use of Potassium Bromate: Bromination of Halobenzenes and Halobenzoic Acids
Syntheses of bromo compounds by the bromination of halobenzenes and halobenzoic acids using potassium bromate under acidic condition have been discussed.
Banerjee, Amalendu,Banerjee, Gopal Chandra,Dutt, Sachchidananda,Banerjee, Santa (Mrs.),Samaddar, Haraprasad
p. 640 - 642
(2007/10/02)