- PROCESS FOR PREPARATION OF 5-BROMO-1, 2, 3-TRICHLOROBENZENE
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The present invention relates to a process for preparation of 5-bromo-1,2,3-trichlorobenzene of formula (I) in simple, economical manner with high yield. The 5-bromo-1,2,3-trichlorobenzene of formula (I) is used in preparation of 1-(3,4,5-trichloro-phenyl)-2,2,2-trifluoro-ethanone which is a key intermediate of isoxazoline derivatives. (I)
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Page/Page column 12
(2021/08/06)
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- Stepwise mechanism for the bromination of arenes by a hypervalent iodine reagent
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A mild, metal-free bromination method of arenes has been developed using the combination of bis(trifluoroacetoxy)iodobencene and trimethylsilyl bromide. In situ-formed dibromo(phenyl)-λ3-iodane (PhIBr2) is proposed as the reactive intermediate. This methodology using PIFA/TMSBr has been applied with success to a great number of substrates (25 examples). The treatment of mono-substituted activated arenes led to para-brominated products (2u-z) in excellent 83-96% yields. Density functional theory calculations indicate a stepwise mechanism involving a double bromine addition followed by a type II dyotropic reaction with concomitant re-aromatization of the six-membered ring.
- Arrieta, Ana,Cossío, Fernando P.,Granados, Albert,Shafir, Alexandr,Vallribera, Adelina
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p. 2142 - 2150
(2020/03/11)
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- Visible-light photocatalytic activation of N-chlorosuccinimide by organic dyes for the chlorination of arenes and heteroarenes
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A variety of arenes and heteroarenes are chlorinated in moderate to excellent yields using N-chlorosuccinimide (NCS) under visible-light activated conditions. A screening of known organic dye photocatalysts resulted in the identification of methylene green as the most efficient catalyst to use with NCS. According to mechanistic studies described within, the reaction is speculated to proceed via a single electron oxidation of NCS utilizing methylene green under visible-light photoredox pathway. The photo-oxidation of NCS amplifies the electrophilicity of the chlorine atom of the NCS, thus leading to enhanced reactivity as a chlorinating reagent with aromatic substrates.
- Rogers, David A.,Gallegos, Jillian M.,Hopkins, Megan D.,Lignieres, Austin A.,Pitzel, Amy K.,Lamar, Angus A.
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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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- Cu-mediated selective bromination of aniline derivatives and preliminary mechanism study
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A simple and efficient bromination of aniline, aniline derivatives, and analogs have been developed. Forty three examples were given and the highest yield reached was 98%. Different substrates including substituted aniline, pyridin-amine, N-substituted aniline, N,N-disubstituted aniline, N-phenyl-amide, N-phenyl-sulfonamide, and nitrogen-containing heterocycles were all reactive and selectively generated desired bromo-products. The method can be applied to synthesize drug intermediate and quinoxaline derivatives.
- Zhao, Hong-Yi,Yang, Xue-Yan,Lei, Hao,Xin, Minhang,Zhang, San-Qi
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supporting information
p. 1406 - 1415
(2019/05/01)
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- Identification of bromination products of chloro-substituted anilines in aqueous environment by gas chromatography
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To reduce the detection limits of aniline and its various chloroderivatives (all isomers of mono- and dichloroanilines, 2,4,5 -, 2,4,6-, and 3,4,5-trichloroanilines, pentachloroaniline) in aqueous media we suggested bromination reaction, followed by gas chromatographic definition bromo derivatives of chloroanilines on a selective electron capture detector. To identify the products of bromination of chloroaniline in combination with mass-spectrometric data we used chromatographic retention indices on standard nonpolar polydimethylsiloxane stationary phase that was determined for 50 compounds in this class. The technique of identifying bromoderivatives of chloroaniline in water was developed at the gas-chromatographic analysis in the selective electron capture detector. To improve the reliability of the identification of additional bromoderivatives of chloroanilines we obtained their trifluoroacetyl derivatives.
- Gruzdev,Filippova,Zenkevich,Kondratenok
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experimental part
p. 1748 - 1759
(2012/02/15)
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- Electrochemical reductive cleavage of carbon-halogen bonds in 5-bromo-1,3-dichloro-2-iodobenzene
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The electrochemical reduction of carbon-halogen bonds in 5-bromo-1,3-dichloro-2-iodobenzene follows quadratic activation-driving force relationship except in one of the carbon-chlorine bonds. The variation of the transfer coefficient with the electrode potential has been estimated using the voltammetric data coupled with the convolution analysis. The standard potentials pertaining to the reduction of carbon-halogen bonds are evaluated using the Marcus theory of outer sphere electron transfer.
- Prasad, M. Arun,Sangaranarayanan
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p. 10967 - 10972
(2007/10/03)
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- The electrophilic substitution of some 2,4- and 2,6- dihaloacetanilides
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The orientation of electrophilic substitution of some 2,4- and 2,6-dihaloacetanilides has been examined by NMR methods. Mixed acid nitration of 2,6-dichloro and 2-chloro-6-methylacetanilides gave predominantly the 3-nitro derivatives.
- Hanson, James R.,Saberi, Hamid
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p. 699 - 701
(2007/10/03)
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- Liquid phase regioselective bromination of aromatic compounds over HZSM-5 catalyst
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A simple, efficient, regioselective and environmentally safe method for oxybromination of activated aromatics catalyzed by HZSM-5 is reported. The electrophilic substitution of bromine generated from KBr using HZSM-5 as a catalyst and H2O2 as an oxidant.
- Narender,Srinivasu,Kulkarni,Raghavan
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p. 3669 - 3675
(2007/10/03)
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- 2,4,6-Halogeno-aniline derivatives
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The title compounds, 2,4-dibromo-6-chloroaniline, C6H4-Br2ClN, (1), N-acetyl-4-bromo-2,6-dichloroaniline (alternative name: 4′-bromo-2′,6′-dichloroacetanilide), C8H6-BrCl2NO, (2), and N-formyl-4-bromo-2,6-difluoroaniline [alternative name: N-(4-bromo-2,6-difluorophenyl)formamide], C7H4BrF2NO, (3), all have at least one short cell axis (in the range 4.2-4.7 A) and contain molecules which are linked to form infinite chains along the short-axis directions via N-H...N or N-H...O hydrogen bonds. Compound (1) has halogen disorder at the 2 and 6 positions.
- Ferguson, George,Low, John N.,Penner, Glenn H.,Wardell, James L.
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p. 1974 - 1977
(2007/10/03)
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- Oxidative Bromination of Aromatic Amides using Sodium Perborate as Oxidant
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Sodium perborate in glacial acetic acid-acetic anhydride with potassium bromide and sodium tungstate as a catalyst, provides a novel system for the bromination of aromatic amides.
- Hanson, James R.,Harpel, Simone,Medina, Inmaculada C. Rodriguez,Rose, Dorian
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p. 432 - 433
(2007/10/03)
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