- Mild chlorination of aromatic compounds with tin(IV) chloride and lead tetraacetate
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SnCl4/Pb(OAc)4 acts as a safe source of Cl2 for the chlorination of aromatic compounds. A variety of aromatic compounds are effectively chlorinated with SnCl4/Pb(OAc)4 under mild conditions. The mixture is a selective chlorinating agent, particularly with polyalkylbenzenes, polycyclic aromatic compounds and anisoles.
- Muathen, Hussni A.
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Read Online
- Eco-compatible zeolite-catalysed continuous halogenation of aromatics
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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
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Read Online
- Highly para-Selective Mono-Chlorination of Aromatic Compounds Under Mild Conditions by t-Butyl Hypochlorite in the Presence of Zeolites
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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
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Read Online
- Decarboxylative Ipso Halogenation of Mercury(II) Pyridinecarboxylates. Facile Formation of 3-Iodo- and 3-Bromopyridines
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Treatment of mercury(II) nicotinate with iodine and bromine in nitrobenzene at 180-185 deg C for 2 h afforded 3-iodo- and 3-bromopyridines in 44percent and 27percent yields, respectively, without any regioisomers and dihalopyridines.From mercury(II) picolinate only 2-3percent of 2-bromopyridine was obtained under similar reaction conditions, while the reaction using mercury(II) isonicotinate did not give any products.When a mixture of nicotinic acid and HgO was used in place of mercury(II) nicotinate, the halodecarboxylation occurred with similar ease.An ionic pathway involving the initial attack of electrophilic Hg(II) species on the ring-C bearing carboxyl group to afford a 3-pyridylmercury(II) compound and the subsequent replacement of the Hg(II) moiety by electrophilic iodine and bromine was proposed for this reaction.
- Uemura, Sakae,Tanaka, Sakuya,Okano, Masaya,Hamana, Masatomo
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Read Online
- Poly-N-bromosulfonamide-melamine as a novel brominating reagent for regioselective ipso-bromination of arylboronic acids
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A practical synthetic method for the synthesis of aryl bromide was developed through regioselective bromination of boronic acid in the presence of poly-N-bromosulfonamide-melamine (PBBSM). In this regard, a novel heterogeneous support, cross-linked poly sulfonamide-melamine, has been successfully synthesized to stabilize bromine with high surface functional group density (6.6?mmol Br+/g). The prepared reagent is a novel brominating reagent that combines the effective functions of N-bromosulfonamide, N-bromosulfonamide-melamine, and melamine groups. The structure of PBBSM was characterized using XRD, FT–IR, 1H NMR, TGA, FE-SEM, EDX, and TGA analysis. Graphic abstract: [Figure not available: see fulltext.]
- Alavinia, Sedigheh,Ghorbani-Vaghei, Ramin
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p. 1269 - 1276
(2021/08/27)
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- The graphite-catalyzed: ipso -functionalization of arylboronic acids in an aqueous medium: metal-free access to phenols, anilines, nitroarenes, and haloarenes
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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
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p. 18040 - 18049
(2021/05/29)
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- Orthogonal Stability and Reactivity of Aryl Germanes Enables Rapid and Selective (Multi)Halogenations
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While halogenation is of key importance in synthesis and radioimaging, the currently available repertoire is largely designed to introduce a single halogen per molecule. This report makes the selective introduction of several different halogens accessible. Showcased here is the privileged stability of nontoxic aryl germanes under harsh fluorination conditions (that allow selective fluorination in their presence), while displaying superior reactivity and functional-group tolerance in electrophilic iodinations and brominations, outcompeting silanes or boronic esters under rapid and additive-free conditions. Mechanistic experiments and computational studies suggest a concerted electrophilic aromatic substitution as the underlying mechanism.
- Deckers, Kristina,Fricke, Christoph,Schoenebeck, Franziska
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supporting information
p. 18717 - 18722
(2020/08/25)
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- Metal- and base-free synthesis of aryl bromides from arylhydrazines
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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
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supporting information
(2020/05/08)
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- ipso-Bromination/iodination of arylboronic acids: Poly(4-vinylpyridine)-Br2/I2 complexes as safe and efficient reagents
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Poly(4-vinyl pyridine) supported bromine/iodine complexes were prepared and probed for ipso-bromination/iodination of arylboronic acids. These solid complexes with catalytic amount of additive are found to be safe and efficient reagent system for the ipso-bromination/iodination. The reaction occurs under mild conditions and tolerates various functional groups resulting in products with high selectivity and yields.
- Fu, Fang,Gurung, Laxman,Czaun, Miklos,Mathew, Thomas,Prakash, G.K. Surya
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supporting information
(2019/08/26)
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- Amplification of Trichloroisocyanuric Acid (TCCA) Reactivity for Chlorination of Arenes and Heteroarenes via Catalytic Organic Dye Activation
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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.
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supporting information
p. 4229 - 4233
(2019/06/17)
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- Direct Transformation of Arylamines to Aryl Halides via Sodium Nitrite and N-Halosuccinimide
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A one-pot universal approach for transforming arylamines to aryl halides via reaction with sodium nitrite (NaNO2) and N-halosuccinimide (NXS) in DMF at room temperature under metal- and acid-free condition is described. This new protocol that is complementary to the Sandmeyer reaction, is suggested to involve the in situ generation of nitryl halide induce nitrosylation of aryl amine to form the diazo intermediate which is halogenated to furnish the aryl halide.
- Mukhopadhyay, Sushobhan,Batra, Sanjay
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supporting information
p. 14622 - 14626
(2018/09/21)
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- A general electrochemical strategy for the Sandmeyer reaction
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Herein we report a general electrochemical strategy for the Sandmeyer reaction. Using electricity as the driving force, this protocol employs a simple and inexpensive halogen source, such as NBS, CBrCl3, CH2I2, CCl4, LiCl and NaBr for the halogenation of aryl diazonium salts. In addition, we found that these electrochemical reactions could be performed using anilines as the starting material in a one-pot fashion. Furthermore, the practicality of this process was demonstrated in the multigram scale synthesis of aryl halides using highly inexpensive graphite as the electrode. A series of detailed mechanism studies have been performed, including radical clock and radical scavenger study, cyclic voltammetry analysis and in situ electron paramagnetic resonance (EPR) analysis.
- Liu, Qianyi,Sun, Beiqi,Liu, Zheng,Kao, Yi,Dong, Bo-Wei,Jiang, Shang-Da,Li, Feng,Liu, Guoquan,Yang, Yang,Mo, Fanyang
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p. 8731 - 8737
(2018/12/10)
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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 00139; 00145
(2017/07/28)
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- Aerobic oxidative bromination of arenes using an ionic liquid as both the catalyst and the solvent
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A method for the bromination of alkoxy-substituted benzenes and naphthalenes was developed by using the residual oxygen in the reaction tube as the oxidant, and [Bmim]NO3 (1-butyl-3-methylimidazolium nitrate) ionic liquid as both the catalyst and the solvent. No other reagent apart from the ionic liquid and molecular bromine was used in the reactions, and basically all the bromine atoms in the bromine source were transferred to the bromination products, showing that the presented protocol is highly atom economic and practical.
- Ren, Yun-Lai,Wang, Binyu,Tian, Xin-Zhe,Zhao, Shuang,Wang, Jianji
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supporting information
p. 6452 - 6455
(2015/11/16)
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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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- A new recoverable Au(III) catalyst supported on magnetic polymer nanocomposite for aromatic bromination
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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
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supporting information
p. 1063 - 1066
(2013/04/10)
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- The oxidative halogenations of arenes in water using hydrogen peroxide and halide salts over an ionic catalyst containing sulfo group and hexafluorotitanate
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An ionic compound, bis[1-methyl-3-(3′-sulfopropyl)imidazolium] hexafluorotitanate (1), was proved to be the efficient and recyclable catalyst for the oxidative halogenations of arenes in water using H2O 2 as the oxidant and halide salts as the halogenation sources. The mono-halogenated products were obtained selectively by this method. The synergetic catalytic effect coming from the two incorporated functionalities of SO3H and [TiF6]2- was manifested in 1. The halogenation rate catalyzed by 1 was in the ranking of NaBr NaCl > KI. The UV-vis and FT-IR analyses indicated that the successful formation and regeneration of the active peroxo-Ti species (1A) with the aid of proton acid guaranteed the recycling uses of 1.
- Wang, Ling,Wang, Sa-Sa,Vo-Thanh, Giang,Liu, Ye
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- Halogenation and DNA cleavage via thermally stable arenediazonium camphorsulfonate salts
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A series of stable arenediazonium camphorsulfonate salts (2a-2j) were synthesized by simple diazotization of several aromatic amines in the presence of sodium nitrite and camphorsulfonic acid. All the new arenediazonium camphorsulfonates, which were characterized by multinuclear (1H and 13C) NMR, IR, DSC, and X-ray diffraction analysis (2e and 2f) provide unambiguous proof for the molecular structures of 2e and 2f. The efficient application of these salts in halogenation reactions was studied in solvent and solvent-free conditions and the DNA cleavage activity was also assessed. These arenediazonium camphorsulfonate salts are noticed as efficient DNA cleaving agents.
- Vajpayee, Vaishali,Moon, Mi Eun,Lee, Sunmi,Ravikumar, Sambandam,Kim, Hyunuk,Ahn, Byungchan,Choi, Seoyoon,Hong, Soon Ho,Chi, Ki-Whan
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p. 3511 - 3517
(2013/04/23)
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- Halogen exchange via a halogenation of diaryliodonium salts with cuprous halide
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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
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p. 541 - 548
(2014/01/06)
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- Chloroarylation and thiocyanatoarylation of itaconic acid
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Under conditions of Meerwein reaction and anionarylation the aryldiazonium salts and itaconic acid form 2-chloro(thiocyanato)-2-benzylbutanedioic acids as the chloro- and thiocyianatoarylation products. The reaction is not accompanied by the decarboxylati
- Baranovskii,Petrushka,Fesak,Grishchuk
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p. 325 - 328
(2013/08/15)
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- Tetraflic acid (1,1,2,2-Tetrafluoroethanesulfonic acid, HC 2F4SO3H) and gallium tetraflate as effective catalysts in organic synthesis
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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.
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p. 2163 - 2171
(2012/11/07)
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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
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supporting information
p. 2380 - 2383
(2013/02/21)
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- Metal-free chlorodeboronation of organotrifluoroborates
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A mild and metal-free method for the chlorodeboronation of organotrifluoroborates using trichloroisocyanuric acid (TCICA) was developed. Aryl-, heteroaryl-, alkenyl-, alkynyl-, and alkyltrifluoroborates were converted into the corresponding chlorinated products in good yields. This method proved to be tolerant of a broad range of functional groups.
- Molander, Gary A.,Cavalcanti, Livia N.
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experimental part
p. 7195 - 7203
(2011/10/13)
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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
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scheme or table
p. 451 - 454
(2010/08/04)
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- Efficient and economic halogenation of aryl amines via arenediazonium tosylate salts
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Arenediazonium tosylate salts have been successfully employed as a new and efficient reagent in halogenation reactions. A novel and economic protocol has been developed for the bromination and chlorination of various anilines using arenediazonium tosylate salts. A wide variety of reaction conditions were studied in acetonitrile at either room temperature or 60 °C in the presence or absence of catalyst with good to excellent yields. A surprising result showed the formation of acetanilides as a major product of aniline and methyl-substituted aniline halogenations in high yields.
- Lee, Young Min,Moon, Mi Eun,Vajpayee, Vaishali,Filimonov, Victor D.,Chi, Ki-Whan
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experimental part
p. 7418 - 7422
(2010/10/01)
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- An expeditious and environmentally benign preparation of aryl halides from aryl amines by solvent-free grinding
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An efficient solvent-free methodology for conversion of various aryl amines into bromides and chlorides via arenediazonium tosylate salts under grinding conditions is disclosed. This new methodology not only avoids the use of strong acids and expensive reagents for diazotization-halogenation reactions, but also decreases the amount of organic waste from the reaction process.
- Moon, Mi Eun,Choi, Younghwa,Lee, Young Min,Vajpayee, Vaishali,Trusova, Marina,Filimonov, Victor D.,Chi, Ki-Whan
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scheme or table
p. 6769 - 6771
(2011/03/17)
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- Gold-catalyzed halogenation of aromatics by N-halosuccinimides
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(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
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scheme or table
p. 2028 - 2032
(2010/06/17)
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- Direct halogenation of organic compounds with halides using oxone in water - A green protocol
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Direct bromination and iodination of various aromatic compounds with NaBr and NaI using oxone (2KHSO5·KHSO4·K 2S04) in water was accomplished successfully in high-to-excellent yields. The main benefit of this protocol is the performance of the reactions in water in the presence of a harmless oxidant without the use of any organic cosolvents. Using NaBr and NaI as the safe sources of halogens is another advantage of the protocol. This method is easily applicable to the large-scale operations. We have also applied this method successfully for the iodocyclization of an unsaturated alcohol and an unsaturated carboxylic acid.
- Firouzabadi,Iranpoor,Kazemi
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experimental part
p. 1675 - 1681
(2010/01/29)
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- Highly efficient halogenation of organic compounds with halides catalyzed by cerium(III) chloride heptahydrate using hydrogen peroxide as the terminal oxidant in water
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In this article a new environmentally friendly catalytic method is described for the efficient monoiodination and bromination of arenes and also iodoetherification and iodolactonization of olefins using hydrogen peroxide as the terminal oxidant. The method is based on using sodium iodide or sodium bromide, hydrogen peroxide (35%) and cerium(III) chloride as an effective catalyst in water at room temperature or under reflux conditions. By this protocol, iodination of anilines proceeded with high regioselectivity at the para position with the formation of small amounts of the ortho isomers. However, bromination of anilines proceeded with absolute regioselectivity to give the para isomers as the sole products in high yields. Iodinations and bromi-nations of m-xylene, toluene, chloro- and bromobenzenes were proceeded with excellent regioselectivity to produce the para isomers as the sole products. Benzene was also halogenated by this catalytic system to give the monohalogenated benzene in good yields. Iodoetherification and iodolactonization of olefins also proceeded easily in high yields at room temperature. However, the bromination of olefins by this protocol failed and the starting materials were detected intact.
- Firouzabadi, Habib,Iranpoor, Nasser,Kazemi, Somayeh,Ghaderi, Arash,Garzan, Atefeh
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experimental part
p. 1925 - 1932
(2011/03/18)
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- Relative basicities of ortho-, meta-, and para-substituted aryllithiums
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(Chemical Equation Presented) The relative basicities of aryllithiums bearing methoxy, chlorine, fluorine, trifluoromethyl and trifluoromethoxy substituents at the ortho, meta, and para positions have been assessed. To this end, two aryllithiums of compar
- Gorecka-Kobylinska, Joanna,Schlosser, Manfred
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experimental part
p. 222 - 229
(2009/04/11)
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- Halo- and azidodediazoniation of arenediazonium tetrafluoroborates with trimethylsilyl halides and trimethylsilyl azide and Sandmeyer-type bromodediazoniation with Cu(I)Br in [BMIM][PF6] ionic liquid
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(Chemical Equation Presented) Reaction of [ArN2][BF4] salts immobilized in [BMIM][PF6] ionic liquid (IL) with TMSX (X = I, Br) and TMSN3 represents an efficient method for the preparation of iodo-, bromo-, and azido-derivatives via dediazoniation. The reactions can also be effected starting with ArNH2 by in situ diazotization with [NO][BF4] followed by reaction with TMSX or TMSN3. Depending on the substituents on the benzenediazonium cation, competing fluorodediazoniation (ArF formation) and hydrodediazoniation (ArH formation) were observed. Dediazoniation with TMSN3 and with TMSI generally gave the highest chemoselectivity toward ArN3 and ArI formation. The IL was recycled and reused up to 5 times with no appreciable decrease in the conversions. Multinuclear NMR monitoring of the interaction of [ArN 2][BF4]/TMSX, [BMIM][PF6]/TMSX, and [BMIM][PF6]/TMSX/[ArN2][BF4] indicated that TMSF is formed primarily via [ArN2][BF4]/ TMSX, generating [ArN2][X] in situ, which gives ArX on dediazoniation. Competing formation of ArF in Sandmeyer-type bromodediazoniation of [ArN 2][BF4] with Cu(I)Br immobilized in the IL points to significant involvement of heterolytic dediazoniation.
- Hubbard, Abigail,Okazaki, Takao,Laali, Kenneth K.
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p. 316 - 319
(2008/09/17)
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- A novel synthesis of bromobenzenes using molecular bromine
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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
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p. 2478 - 2483
(2008/03/13)
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- Catalytic Sandmeyer bromination
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An efficient catalyst system for Sandmeyer bromination is proposed. Aryl bromides and dibromides can be obtained with excellent yield by this synthetic protocol. Georg Thieme Verlag Stuttgart.
- Beletskaya, Irina P.,Sigeev, Alexander S.,Peregudov, Alexander S.,Petrovskii, Pavel V.
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p. 2534 - 2538
(2008/03/13)
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- Regioselective bromination of aromatic compounds with Br 2/SO2Cl2 over microporous catalysts
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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.
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p. 4465 - 4468
(2007/10/03)
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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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- Monohalogenation (bromination and iodination) of electron rich arenes by tetraalkylammonium halides in presence of conc. H2SO4
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Arenes undergo electrophilic substitution reaction when treated with tetraalkylammonium halides (bromides and iodides) in presence of conc. H 2SO4 to give p-haloarenes in high yields.
- Myint, Yi Yi,Pasha
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p. 357 - 360
(2007/10/03)
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- Oxidative monobromination of electron-rich arenes by conc. H 2SO4/alkali metal bromides
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The reaction of electron-rich arenes with alkali metal bromides such as sodium and potassium bromides in the presence of cone. H2SO 4 to give p-bromoarenes is reported. The reaction is possible in the absence of any specialised oxidising agents and the yields are high.
- Myint, Yi Yi,Pasha
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p. 732 - 734
(2007/10/03)
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- Halogenation of Aromatic Compounds by N-chloro-, N-bromo-, and N-iodosuccinimide
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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
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p. 932 - 933
(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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- CARBOXYLIC ACID DERIVATIVES AND DRUGS CONTAINING THE SAME
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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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- 1-Aryl-3,3-dialkyltriazenes: A convenient synthesis from dry arenediazonium o-benzenedisulfonimides - A high yield break down to the starting dry salts and efficient conversions to aryl iodides, bromides and chlorides
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This research comprises three parts. The first part regards the synthesis of 1-aryl-3,3-dialkyltriazenes 3 by reaction of dry arenediazonium o-benzenedisulfonimides 1, also coming from weakly basic aromatic amines with dimethylamine or diethylamine in aqueous solution at 0-5 °C. Yields were usually greater than 90% and there was the possibility of recovering the o-benzenedisulfonimide (5), which could be reused to prepare the salts 1. In the second part it was demonstrated that there is the possibility of reconverting the triazenes 3 into the starting stable dry salts 1 by using 5 as acid. The reactions were carried out in glacial acetic acid at 50-55 °C and normally afforded salts 1 in yields of around 90-99%. The third part concerns the setting up of two procedures for the conversion of 3 to aryl iodides 9, bromides 10 and chlorides 11. Procedure A used the corresponding aqueous hydrogen halides in acetonitrile at r.t. or 60 °C, sometimes in the presence of aqueous HBF4, sometimes Cu powder (25 examples, yields 65%-88%). Procedure B usually used anhydrous methanesulfonic acid and tetraalkylammonium halides in anhydrous acetonitrile at temperatures varying from r.t. to 80 °C, sometimes in the presence of Cu (16 examples, yields 65-88%).
- Barbero,Degani,Diulgheroff,Dughera,Fochi
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p. 2180 - 2190
(2007/10/03)
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- Highly efficient and selective electrophilic and free radical catalytic bromination reactions of simple aromatic compounds in the presence of reusable zeolites
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Reactions of mono-substituted aromatics of moderate activity with bromine in the presence of stoichiometric amounts of zeolite NaY proceed in high yield and with high selectivity to the corresponding para-bromo products. The zeolites can easily be regenerated by heating and reused. Similar para-selectivity can be achieved in the case of toluene by use of tert-butyl hypobromite as reagent, zeolite HX as catalyst, and a solvent comprising a mixture of tetrachloromethane and diethyl ether. Radical bromination of ethyl 4-methylbenzoate using bromine in the presence of light is catalysed by various zeolites and affords a high yield of ethyl 4-(bromomethyl)benzoate but with no great improvement in selectivity for monobromination.
- Smith, Keith,El-Hiti, Gamal A.,Hammond, Mark E.W.,Bahzad, Dawoud,Li, Zhaoqiang,Siquet, Christophe
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p. 2745 - 2752
(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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- Mild preparation of haloarenes by ipso-substitution of arylboronic acids with N-halosuccinimides
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Aryl and heteroaryl boronic acids react with N-iodosuccinimide and N-bromosuccinimide to give the corresponding iodo-and bromo- arenes in good to excellent yields. The reaction is usually highly regioselective and yields only the ipso-substituted product. Esters of arylboronic acids react similarly, but less readily.
- Thiebes, Christoph,Prakash, G. K. Surya,Petasis, Nicos A.,Olah, George A.
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p. 141 - 142
(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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- Arenediazonium tetrachlorocuprates(ii). Modification of the meerwein and sandmeyer reactions
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In the copper-catalysed reactions of arenediazonium chlorides with unsaturated compounds arenediazonium tetrachlorocuprates(II) are formed as intermediates. A general method of preparation of these complexed diazonium salts is described. In polar solvents these salts undergo chlorinative dediazoniation to give chloroarenes in high yield. The reaction of an arenediazonium tetrachlorocuprate(II) with an activated alkene results in the same products as the Meerwein reaction. A radical cation mechanism for this reaction is proposed.
- Obushak, Mykola D.,Lyakhovych, Mykhaylo B.,Ganushchak, Mykola I.
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p. 9567 - 9570
(2007/10/03)
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- Detection of Aryl Radicals in Hydrodediazoniations
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Iodoacetic acid, an effective aryl radical trapping agent, was employed to investigate the reactive intermediates in several hydrodediazoniations. Isolation of an aryl iodide constitutes a positive result in the test for aryl radicals. Equally as important is the lower yield of the reduction product when the trap diverts radicals from their usual reaction path. Hydrodediazoniations performed in MeOH, EtOH, i-PrOH, benzyl alcohol, THF, tetramethylurea, formamide, and hypophosphorous acid all involve aryl radical intermediates. Ferrocene was found to be an effective initiator in most of these reactions; through its action as an electron donor, it serves to shorten reaction times and to improve yields of hydrodediazoniation products. All hydrodediazoniations examined, whether initiated or not, involve radical intermediates.
- Wassmundt, Frederick W.,Kiesman, William F.
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p. 8304 - 8308
(2007/10/03)
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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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- THIOCYANATO-, BROMO-, AND CHLOROARYLATION OF TRICHLOROETHYLENE
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By reactions of arenediazonium salts with trichloroethylene in aqueous acetone in the presence of alkali metal thiocyanates, bromides, or chlorides, catalyzed by Cu(II) or Fe(II) salts, we synthesized 1-thiocyanato(bromo, chloro)-1,2,2-trichloro-2-arylethanes.These were treated with alcoholic potassium hydroxide to give α,β,β-trichlorostyrenes.Trichloroethylene is less reactive in the anionarylation than vinylidene and vinyl chlorides.
- Grishchuk, B. D.,Kudrik, E. Ya.,Gorbovoi, P. M.,Garmider, V. L.,Ganushchak, N. I.
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p. 1164 - 1166
(2007/10/02)
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