- A convenient and efficient H2SO4-promoted regioselective monobromination of phenol derivatives using N-bromosuccinimide
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A convenient, rapid H2SO4-promoted regioselective monobromination reaction with N-bromosuccinimide was developed. The desired para-monobrominated or ortho-monobrominated products of phenol derivatives were obtained in good to excellent yields with high selectivity. Regioselective chlorination and iodination were also achieved in the presence of H2SO4 using N-chlorosuccinimide and N-iodosuccinimide, respectively.
- Wu, Yong-Qi,Lu, Hai-Jia,Zhao, Wen-Ting,Zhao, Hong-Yi,Lin, Zi-Yun,Zhang, Dong-Feng,Huang, Hai-Hong
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p. 813 - 822
(2020/02/15)
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- Method for photocatalytic synthesis of polybrominated phenol compound in water phase
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The invention discloses a method for photocatalytic synthesis of a polybrominated phenol compound in a water phase, comprising the following steps: adding a catalytic amount of a radical initiator, aphenol derivative and low-toxic and cheap bromide salt and water into a reaction vessel, reacting at room temperature at 5 W power in a photocatalytic reactor for a certain period, extracting with ethyl acetate and then re-crystallizing to obtain a polybrominated phenol compound. The above radical initiator is eosin, azobisisobutanol, sodium persulfate, ammonium persulfate or potassium persulfate.The free radical initiator and the bromine salt are cheap and easily available, and the method is an ideal synthesis method of the polybrominated phenol compound. According to the method, low-toxicity bromine salt instead of liquid bromine is used to carry out a bromination reaction, unstable and explosive hydrogen peroxide is replaced with the cheap and easily-available free radical initiator, and an emerging photocatalytic method is used. The polybrominated phenol compound can be obtained in a high yield by only using a 5W power lamp for the reaction, the reaction selectivity is high, by-products are less, and the post-treatment is simple.
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Paragraph 0012; 0024
(2019/08/30)
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- A new process to prepare 3,6-dichloro-2-hydroxybenzoic acid, the penultimate intermediate in the synthesis of herbicide dicamba
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Glyphosate [N-(phosphonomethyl)glycine] is a broad spectrum, post-emergent herbicide that is among the most widely used agrochemicals globally. Over the past 30 years, there has been a development of glyphosate-resistant weeds, which pose a significant challenge to growers and crop scientists, resulting in lower crop yields and increased costs. 3,6-Dichloro-2-methoxybenzoic acid (dicamba) is the active ingredient in XtendiMax a standalone herbicide developed by Bayer Crop Science to control broadleaf weeds, including glyphosate-resistant species. 3,6-Dichloro-2-hydroxybenzoic acid (3,6-DCSA) is the penultimate intermediate in the synthesis of dicamba. Existing dicamba manufacturing routes utilize a high temperature, high pressure Kolbe-Schmitt carboxylation to prepare 3,6-DCSA. Described in this Letter is a new, non-Kolbe-Schmitt process to prepare 3,6-DCSA from salicylic acid in four chemical steps.
- Walker, Daniel P.,Harris, G. Davis,Carroll, Jeffery N.,Boehm, Terri L.,McReynolds, Matthew D.,Struble, Justin R.,van Herpt, Jochem,van Zwieten, Don,Koeller, Kevin J.,Bore, Mangesh
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supporting information
p. 1032 - 1036
(2019/03/17)
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- Graphene Oxide Promoted Oxidative Bromination of Anilines and Phenols in Water
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The mildly acidic and oxidative nature of graphene oxide, with its large surface area available for catalytic activity, has been explored in aromatic nuclear bromination chemistry for the first time. The versatile catalytic activity of graphene oxide (GO) has been used to selectively and rapidly brominate anilines and phenols in water. The best results were obtained at ambient temperatures using molecular bromine in a protocol promoted by oxidative bromination catalyzed by GO; these transformations proceeded with 100% atom economy with respect to bromine and high selectivities for the tribromoanilines and -phenols. Reduced graphene oxide (r-GO) was observed to form after the second recycle (third use) of GO. This technique is also effective with N-bromosuccinimide (NBS) as the brominating reagent. In the case of NBS, reactions were instantaneous and the GO displayed excellent recyclability without any loss of activity over several cycles.
- Ghorpade, Prashant Vasantrao,Pethsangave, Dattatray Appasha,Some, Surajit,Shankarling, Ganapati Subray
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p. 7388 - 7397
(2018/07/29)
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- Method for the synthesis of many halo benzoic acid
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The invention provides a poly-halogenated benzoic acid synthesizing method. The method comprises the following steps: dissolving substituted benzoic acid, halogen and organic strong acid in a polar solvent for increasing temperature, after oxidation at a temperature of 50-70 DEG C, performing heat preservation at the temperature of 60-80 DEG C for 2-6 h, adding a right amount of water, and cooling to a room temperature, so as to obtain poly-halogenated benzoic acid. According to the invention, synthetic reaction is performed in an alcohols solvent, the halogen simple substance is used as a halogenating reagent, a small amount of organic strong acid is added, used as a catalyst, and used for catalyzing the electrophilic substitution reaction of the halogen to benzene rings, and hydrogen peroxide is dropwise added during the reaction to enable the halogen simple substance in the reaction system to be oxidized into halide ions so as to improve the utilization rate of the halogen and achieve the effect of atom economy.
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Paragraph 0039
(2017/04/03)
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- 3,6-DICHLOROSALICYLIC ACID COMPOUNDS AND RELATED SYNTHETIC PROCESSES
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The present disclosure relates, in general, to 5-halo-3,6-dichlorosalicylic acid compounds, 5-halo-3,6-dichlorosalicyaldehyde compounds, processes for preparing 5-halo-3,6-dichlorosalicylic acid compounds, processes for preparing 5-halo-3,6- dichlorosalicyaldehyde compounds, processes for preparing 3,6-dichlorosalicylic acid compounds, and processes that employ such compounds as intermediates in the preparation of the herbicide dicamba.
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Paragraph 0142
(2016/01/26)
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- An instant and facile bromination of industrially-important aromatic compounds in water using recyclable CaBr2-Br2 system
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Various industrially-important brominated intermediates have been instantly synthesized using aq. CaBr2-Br2 system as an efficient and recyclable brominating reagent under aqueous conditions at room temperature without the need for metal catalysts or acidic additives. Structurally-diverse phenol and aniline derivatives with strong electron-withdrawing groups such as carboxylic, nitro and formyl show remarkable reactivity to the brominating reagent and brominated in 92-98% yield with high purity (>99%) in a very short reaction time. Organic solvent-free conditions, a feature of the green chemistry, were successively used not only for the reactions but also for the isolation of products at the end of the reaction. The recycling of HBr by its neutralization, thereby generating additional amounts of industrially-important CaBr2 has been designed and developed. The brominating reagent has been recycled and regenerated, and the process was repeated up to 4 cycles after the fresh batch using the regenerated brominating reagent having almost identical selectivity and isolated yields, which seems to be the most promising methodology from the viewpoint of the green approach to organic synthesis.
- Kumar, Lalit,Mahajan, Tanu,Agarwal
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experimental part
p. 2187 - 2196
(2011/09/16)
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- An efficient regioselective NBS aromatic bromination in the presence of an ionic liquid
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A simple, efficient, and rapid method was developed for high-yielding regioselective monobromination of activated aromatic compounds using NBS in combination with ionic liquid 1-butyl-1-methylimidazolium bromide ([Bmim]Br) or dioxane. The ionic liquid is recyclable and can be reused with minimal loss in the catalytic efficiency if the ionic liquid is rapidly microwaved prior to reactions.
- Pingali, Subramanya R.K.,Madhav, Monika,Jursic, Branko S.
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experimental part
p. 1383 - 1385
(2010/04/25)
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- Regioselective aromatic electrophilic bromination with dioxane dibromide under solvent-free conditions
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Highly regioselective ring bromination of aromatic compounds has been accomplished with high yields and good purity using dioxane dibromide (DD) under solvent-free conditions. Notable features of this methodology include operational simplicity, rapid reactions, excellent control over the degree of bromination, and tolerance of various functional groups during the reaction. Copyright Taylor & Francis Group, LLC.
- Chaudhuri, Subrata Kumar,Roy, Sanchita,Saha,Bhar, Sanjay
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p. 581 - 585
(2007/10/03)
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- Acyl derivatives of 2-aminobenzimidazole and their fungicide activity
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Procedures have been developed for the preparation of methyl 2-benzimidazolylcarbamate, 2-acetylaminobenzimidazole, 2- benzoylaminobenzimidazole, 2-(3,5-dibromo-2-hydroxybenzoylamino)benzimidazole, 1-(3,6-dichloro-2-methoxybenzoyl)-2-aminobenzimidazole, 2-(3,5-dichloro-2- hydroxybenzoylamino)benzimidazole, 2-(3,5-dichloro-2-methoxybenzoylamino) benzimidazole, and 1-(3,5,6-trichloro-2-methoxybenzoyl)-2-aminobenzimidazole. The synthesized compounds have been tested for fungicide activity.
- Pilyugin,Sapozhnikov,Sapozhnikova
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p. 738 - 743
(2007/10/03)
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- Pharmaceutical grade 3,5-dibromosalicylic acid and metohd for synthesizing same
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An improved method of synthesizing 3,5-dibromosalicylic acid provides a highly purified pharmaceutical grade product free of toxic by-products and solvents. The purified product may be utilized as an intermediate in synthesizing pharmaceutical grade substances, as a bactericide when incorporated into topical ointments, and as an adjuvant in drug absorption systems.
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- The Bromination of Salicylate Anions. Evidence for the Participation of the Ortho Carboxylate Group
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Salicylate monoanions show reduced selectivity toward bromine in aqueous solution when compared to similarly substituted phenols.In particular, 5-substituted salicylate ions show ρ+ = -2.69 whereas for para-substituted phenols ρ+ = -5.21.From this and other evidence it is argued that bromine attack on such ions may involve proton transfer from the hydroxyl group to the o-carboxylate to which it is hydrogen bonded. 5-Methylsalicyclic acid (8a) forms, in part, an unstable cyclohexadienone (13) resulting from ipso bromine attack.The breakdown of 13 shows intramolecular catalysis by the o-COOH group, which has an effective molarity of 58 M.The microscopic reverse reaction of bromine on the anion 8a must, therefore, involve the o-CO2- group, as suggested above.Implications with respect to the activating effect of hydroxyl groups on cation-forming reactions are discussed.
- Tee, Oswald S.,Iyengar, N. Rani
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p. 4468 - 4473
(2007/10/02)
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- Kinetics and Mechanism of Oxidation of m-Cresol by Vanadium(V) in Presence of Salicylic and Substituted Salicylic Acids in Dilute Perchloric Acid Medium
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The kinetics of the oxidation of m-cresol by vanadium(V) in presence of salicylic and substituted salicylic acids was studied in perchloric acid medium.The reaction is first order each in V(V) and m-cresol.Plots of 1/k1 vs 1/ (where L represents salicylic or substituted salicylic acid) were found to be linear with positive intercepts on 1/k1-axes, suggesting the formation of a 1:1 complex between V(V) and the ligand which is believed to be a more potent oxidant.The reaction is acid-catalysed and the plot of 1/k1 vs 1/+> was found to be linear with a positive intercept on 1/k1-axis.The applicability of Marcus theory to this reaction is discussed.
- Srinivas, K.,Subbaiah, K. V.,Rao, P. V. Subba
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- Binary and Ternary Chelates of Scandium(III), Yttrium(III) and Lanthanum(III) with Ethyleneglycol-Bis(β-Aminoethylether)-Tetraacetic Acid as Primary and Substituted Salicylic Acids as Secondary Ligands
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Formation constants of binary and ternary complexes of the systems of the type: M-L and M-egta-L have been determined pH-metrically at 25 deg and μ=0.1 M (KNO3) in 50 percent (v/v) aqueous-ethanol medium.The order of stabilities of ternary complexes have compared with those of corresponding binary complexes, and results discussed on the basis of coulombic interactions.
- Pandey, Ashok Kumar,Chandra, M.,Agarwala, B. V.,Dey, A. K.
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