- Palladium-catalyzed ortho-C-H hydroxylation of benzoic acids
-
A simple Pd(OAc)2 catalyzed ortho-hydroxylation of benzoic acids using TBHP as the sole oxidant has been explored. This protocol features relatively broad substrate scope and operational simplicity. The compatibility of ortho-substituted substrates is an effective complement to the previous ortho-hydroxylation reaction.
- Luo, Feihua,He, Shuhua,Gou, Quan,Chen, Jinyang,Zhang, mingzhong
-
-
- A convenient and efficient H2SO4-promoted regioselective monobromination of phenol derivatives using N-bromosuccinimide
-
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
-
p. 813 - 822
(2020/02/15)
-
- Cooperativity within the catalyst: alkoxyamide as a catalyst for bromocyclization and bromination of (hetero)aromatics
-
Alkoxyamide has been reported as a catalyst for the activation ofN-bromosuccinimide to perform bromocyclization and bromination of a wide range of substrates in a lipophilic solvent, where adequate suppression of the background reactions was observed. The key feature of the active site is the alkoxy group attached to the sulfonamide moiety, which facilitates the acceptance as well as the delivery of bromonium species from the bromine source to the substrates.
- Mondal, Haripriyo,Sk, Md Raja,Maji, Modhu Sudan
-
supporting information
p. 11501 - 11504
(2020/10/12)
-
- Stepwise mechanism for the bromination of arenes by a hypervalent iodine reagent
-
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
-
p. 2142 - 2150
(2020/03/11)
-
- Copper and L-(?)-quebrachitol catalyzed hydroxylation and amination of aryl halides under air
-
L-(?)-Quebrachitol, a natural product obtained from waste water of the rubber industry, was utilized as an efficient ligand for the copper-catalyzed hydroxylation and amination of aryl halides to selectively give phenols and aryl amines in water or 95percent ethanol. In addition, the hydroxylation of 2-chloro-4-hydroxybenzoic acid was validated on a 100-g scale under air.
- Bao, Xuefei,Chen, Guoliang,Dong, Jinhua,Du, Fangyu,Li, Hui,Liang, Xinjie,Wu, Ying,Zhang, Yongsheng
-
supporting information
(2020/08/03)
-
- Mild and Regioselective Bromination of Phenols with TMSBr
-
In this work, an unexpected promoting effect of by-product thioether was observed, leading to a mild and regioselective bromination of phenols with TMSBr. This method can tolerate a series of functional groups such as the reactive methoxyl, amide, fluoro, chloro, bromo, aldehyde, ketone and ester groups, and has the potential to recycle the by-product thioether and isolate the desired product under column chromatography-free conditions. Mechanism studies revealed that O–H···S hydrogen bond may be formed between phenol and by-product thioether. Possibly owing to the steric hindrance effect from by-product thioether, the electrophilic bromination at para-position of phenols is much favorable.
- Ma, Xiantao,Yu, Jing,Jiang, Mengyuan,Wang, Mengyu,Tang, Lin,Wei, Mengmeng,Zhou, Qiuju
-
supporting information
p. 4593 - 4596
(2019/07/05)
-
- Continuous production processes of dicamba methyl ester and dicamba methyl ester emulsifiable concentrate
-
The invention provides a continuous production process of dicamba methyl ester. The process comprises the following steps: A) 5-bromo-3,6-dichlorosalicylic acid is subjected to a reaction under an alkaline condition and under the action of metal powder to remove bromine atoms in para-positions of hydroxyl, and 3,6-dichlorosalicylic acid is obtained; B) 3,6-dichlorosalycylic acid and halomethane are subjected to an etherification reaction in a mixed solvent of water and methanol, and methyl 3,6-dichloro-2-methoxybenzoate is obtained; C) methanol is removed by distillation; D) a system after distillation is left to stand for laying, an organic phase is distilled, and dicamba methyl ester is obtained. By means of the preparation process, continuous production can be realized, workers are notrequired to make direct contact with materials, the control degree is high, the production operation environment is greatly improved and safer, the process route and equipment are simple, the production cost is low, besides, the product yield and purity are greatly improved, and a superior route suitable for mass industrial production is provided.
- -
-
Paragraph 0074; 0075; 0080; 0081; 0086; 0087
(2019/06/05)
-
- Preparation method of dicamba
-
The invention provides a preparation method of dicamba. The preparation method comprises the steps as follows: A) salicylic acid and bromine or hydrogen bromide are subjected to a reaction in concentrated sulfuric acid, 5-bromosalicylic acid is obtained; B) 5-bromosalicylic acid and chlorine are subjected to a chlorination reaction, 5-bromo-3,6-dichlorosalycylic acid is obtained; C) 5-bromo-3,6-dichlorosalycylic acid is subjected to a debromination reaction under the alkaline condition and under the action of metal powder, and 3,6-dichlorosalycylic acid is obtained; D) 3,6-dichlorosalycylic acid and halomethane are subjected to an etherification reaction in a mixed solvent of water and methanol, and methyl-3,6-dichloro-2-methoxybenzoate is obtained; E) methanol is removed by distillation;F) a system after distillation is left to stand for laying, an organic phase is distilled, and dicamba methyl ester is obtained; G) dicamba methyl ester is subjected to alkaline hydrolysis, acidification and drying, and dicamba is obtained. The route comprises few steps and has low difficulty, the equipment requirement and investment are lower, continuous production can be realized, no three wastes are produced, and the product yield and purity are higher.
- -
-
Paragraph 0094; 0102; 0107; 0112; 0117; 0122; 0127; 0132
(2019/06/05)
-
- Preparation method of micamba methyl ester
-
The invention provides a preparation method of micamba methyl ester. The preparation method comprises the steps as follows: A) salicylic acid and bromine are subjected to a reaction in concentrated sulfuric acid, 5-bromosalicylic acid is obtained; B) 5-bromosalicylic acid and chlorine are subjected to a chlorination reaction, 5-bromo-3,6-dichlorosalycylic acid is obtained; C) 5-bromo-3,6-dichlorosalycylic acid is subjected to a debromination reaction under the alkaline condition and under the action of metal powder, and 3,6-dichlorosalycylate is obtained; D) 3,6-dichlorosalycylate and halomethane are subjected to a methylation reaction in methanol and a quaternary ammonium salt phase transfer catalyst, and 3,6-dichloro-2-methyl methoxybenzoate is obtained; E) methanol is removed by distillation; F) a system after distillation is left to stand for laying, an organic phase is distilled, and dicamba methyl ester is obtained. By means of the preparation method, the yield and purity are higher, the route is simple and the production cost is low.
- -
-
Paragraph 0077-0078; 0081-0082; 0085-0086; 0089-0090; 0093
(2019/06/13)
-
- Total recycling method of salicylic acid in preparation process of 3,6-dichlorosalicylic acid
-
The invention provides a total recycling method of salicylic acid in a preparation process of 3,6-dichlorosalicylic acid. The method comprises steps as follows: A), salicylic acid is subjected to reaction with bromine or hydrogen bromide in concentrated sulfuric acid, 5-bromosalicylic acid is obtained; B), 5-bromosalicylic acid is subjected to chlorination with chlorine, and 5-bromo-3,6-dichlorosalicylic acid is obtained; C), 5-bromo-3,6-dichlorosalicylic acid is subjected to debromination reaction under the action of a catalyst, and crude 3,6-dichlorosalicylic acid is obtained; D), crude 3,6-dichlorosalicylic acid is recrystallized in xylene or toluene, and pure 3,6-dichlorosalicylic acid and an impurity-containing solvent are obtained, wherein impurities comprise 3-chlorosalicylic acid,3,5-dichlorosalicylic acid and 3-bromo-6-chlorosalicylic acid; E), the impurity-containing solvent is subjected to alkali washing, a water phase is obtained by liquid separation, a catalyst is added to the water phase for hydrogenation dehalogenation reaction, filtering is performed to remove the catalyst, the filtrate is acidified, and salicylic acid is obtained and recycled to step A). Total recycling of salicylic acid is realized, and the environmental benefit is high.
- -
-
Page/Page column 7-11
(2019/06/05)
-
- Preparation method of 3,6-dichlorosalicylic acid
-
The invention provides a preparation method of 3,6-dichlorosalicylic acid. The method comprises the following steps: 5-bromo-3,6-dichlorosalicylic acid is subjected to debromination reaction in the alkaline condition and under action of metal powder, and 3,6-dichlorosalicylic acid is obtained. 5-bromo-3,6-dichlorosalicylic acid is subjected to selective debromination reaction in the alkaline condition and under action of metal powder, the reaction has high selectivity, the conversion rate is high, the reaction rate is high, and the prepared product has high purity. The process route is simple,equipment is conventional, the metal powder is easy to recycle, and the cost is low.
- -
-
Page/Page column 3; 5-7
(2019/06/05)
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- A new process to prepare 3,6-dichloro-2-hydroxybenzoic acid, the penultimate intermediate in the synthesis of herbicide dicamba
-
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
-
supporting information
p. 1032 - 1036
(2019/03/17)
-
- Synthetic method of 5-bromo-2-chlorobenzoic acid
-
The invention discloses a synthetic method of 5-bromo-2-chlorobenzoic acid. The method comprises the following steps of by taking salicylic acid as a starting material, performing bromination reactionto obtain 2-hydroxyl-5-bromo-benzoic acid, and then performing chlorination reaction to obtain the 5-bromo-2-chlorobenzoic acid, wherein a bromination system adopted by the bromination reaction is tetrabutyl ammonium bromide/oxygen/sodium metavanadate, a catalyst is aluminium tribromide, and a solvent is 1,4-dioxane; and a chlorinating agent is carbon tetrachloride, and a catalyst is molybdenum hexacarbonyl. The method provided by the invention adopts the cheap salicylic acid which is wide in source as the starting material and prepares the 5-bromo-2-chlorobenzoic acid through two-step reaction of bromination and chlorination, is novel in synthetic route, relatively low in production cost, relatively small in environmental pollution and very suitable for industrial mass production. According to the method, through the bromination reaction and the chlorination reaction, by selecting proper reagents, relatively high reaction yield and product purity can be obtained.
- -
-
Paragraph 0016; 0048-0050; 0051-0053; 0054-0056; 0057; 0058
(2018/07/30)
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- Synthesis, kinetics, and mechanism of bromophenols by N-bromophthalimide in aqueous acetic acid
-
The kinetics and mechanism of bromination of phenol and its substituents, viz. 4-chlorophenol, 4-bromophenol, 4-methylphenol, and 4-methoxyphenol by N-bromophthalimide (NBP) in the presence of mercuric acetate in the temperature range of 303–318?K in aqueous acetic acid medium have been investigated. The reaction follows first-order dependence on [NBP] and fractional order dependence of rate on [Phenol]. The activation parameters have been evaluated, and based on the observed kinetic results the probable mechanism has been proposed. Observed kinetic features and Hammett's reaction constant (ρ) suggests that bromination occurs through electrophilic substitution of bromonium ion (Br+) into the aromatic ring in the transition state. Large negative entropy of activation values probably suggests the rigid nature of transition state.
- Anjaiah, Birla,Prameela, Kethavath,Srinivas, Pabba,Rajanna, Kamatala Chinna
-
p. 804 - 812
(2018/09/11)
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- Isoquinolinium Dichromate and Chlorochromate as Efficient Catalysts for Oxidative Halogenation of Aromatic Compounds under Acid-Free Conditions
-
Isoquinolinium dichromate and isoquinolinium chlorochromate were found as efficient catalysts to trigger oxidative bromination and iodination of aromatic hydrocarbons with KBr/KI and KHSO4 under acid-free conditions. Reaction times reduced highly significantly under sonication, followed by corresponding mono bromo derivatives in very good yield with high regioselectivity.
- Rao, A. Sambashiva,Rajanna,Reddy, K. Rajendar,Kulkarni, Subhash
-
p. 832 - 837
(2016/02/12)
-
- 3,6-DICHLOROSALICYLIC ACID COMPOUNDS AND RELATED SYNTHETIC PROCESSES
-
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.
- -
-
Paragraph 0133
(2016/01/26)
-
- A Baker-Venkataraman retro-Claisen cascade delivers a novel alkyl migration process for the synthesis of amides
-
A simple extension of the carbamoyl Baker-Venkataraman rearrangement has been developed. If residual water in the reaction is not strictly excluded a Baker-Venkataraman retro-Claisen cascade takes place, giving amide products, in which an alkyl group apparently migrates between two functionalities of the substrate.
- Ameen, Dana,Snape, Timothy J.
-
supporting information
p. 1816 - 1819
(2015/03/30)
-
- Brominations with Pr4NBr9 as a solid reagent with high reactivity and selectivity
-
Tetrapropylammonium nonabromide (Pr4NBr9) is introduced as a room-temperature solid reagent for rapid bromination reactions of various substrates. The reagent exhibits reactivity similar to that of elemental bromine, but shows higher selectivity and it is easier and safer to store and to handle. Georg Thieme Verlag Stuttgart · New York.
- Beck, Thorsten M.,Haller, Heike,Streuff, Jan,Riedel, Sebastian
-
p. 740 - 747
(2014/04/03)
-
- Regioselective ortho-carboxylation of phenols catalyzed by benzoic acid decarboxylases: A biocatalytic equivalent to the Kolbe-Schmitt reaction
-
The enzyme catalyzed carboxylation of electron-rich phenol derivatives employing recombinant benzoic acid decarboxylases at the expense of bicarbonate as CO2 source is reported. In contrast to the classic Kolbe-Schmitt reaction, the biocatalytic equivalent proceeded in a highly regioselective fashion exclusively at the ortho-position of the phenolic directing group in up to 80% conversion. Several enzymes were identified, which displayed a remarkably broad substrate scope encompassing alkyl, alkoxy, halo and amino- functionalities. Based on the crystal structure and molecular docking simulations, a mechanistic proposal for 2,6-dihydroxybenzoic acid decarboxylase is presented.
- Wuensch, Christiane,Gross, Johannes,Steinkellner, Georg,Lyskowski, Andrzej,Gruber, Karl,Glueck, Silvia M.,Faber, Kurt
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p. 9673 - 9679
(2014/03/21)
-
- Simple and improved regioselective brominations of aromatic compounds using N-benzyl-N,N-dimethylanilinium peroxodisulfate in the presence of potassium bromide under mild reactions conditions
-
A simple, efficient, and mild method for the selective bromination of some activated aromatic compounds using N-benzyl-N,N-dimethylanilinium peroxodisulfate in the presence of potassium bromide in non-aqueous solution is reported. The results obtained revealed good to excellent selectivity between the ortho and para positions of phenols and methoxyarenes.
- Ghasemnejad-Bosra, Hassan,Ramzanian-Lehmali, Farhad,Jafari, Somaye
-
experimental part
p. 685 - 692
(2012/01/16)
-
- An efficient regioselective NBS aromatic bromination in the presence of an ionic liquid
-
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.
-
experimental part
p. 1383 - 1385
(2010/04/25)
-
- Kinetics and mechanism of the bromination of salicylic acid
-
Kinetics of the bromination of salicylic acid in aqueous solution by bromine has been studied potentiometrically. The rate shows second order kinetics i.e., first order with respect to salicylic acid and bromine. A suitable mechanism in conformity with the kinetic observations has been proposed. Various activation parameters such as frequency factor, energy of activation and entropy of activation are calculated from kinetic measurements.
- Patil, Dilip B.,Thakur, Gulabsingh J.,Shende, Parmanand M.
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experimental part
p. 5072 - 5076
(2012/07/28)
-
- An efficient, rapid, and regioselective bromination of anilines and phenols with 1-butyl-3-methylpyridinium tribromide as a new reagent/solvent under mild conditions
-
1-Butyl-3-methylpyridinium tribromide, [BMPy]Br3 proves to be a highly efficient, regioselective reagent/solvent for nuclear bromination of various anilines and phenols. The synthesis and characterization of the room temperature ionic liquid [BMPy]Br3 (2) is described. The bromination was carried out in the absence of organic solvents and in most cases the only extraction solvent needed was water. The spent 1-butyl-3-methylpyridinium bromide (1) was easily recycled.
- Borikar, Sanjay P.,Daniel, Thomas,Paul, Vincent
-
scheme or table
p. 1007 - 1009
(2009/05/11)
-
- Regioselective, photochemical bromination of aromatic compounds using N-bromosuccinimide
-
Regioselective nuclear bromination of aromatic compounds is investigated with N-bromosuccinimide as the brominating agent under UV irradiation to afford the corresponding brominated compounds. The reaction proceeds at ambient temperature (30 ± 2 °C) without any catalyst. In most of the reactions, regioselectively mono-brominated products are obtained in good to high yields. The conversion and selectivity for bromination depend on the nature of the substituent on the aromatic ring.
- Chhattise, Prakash K.,Ramaswamy,Waghmode, Suresh B.
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p. 189 - 194
(2008/03/30)
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- Process for the synthesis of hydroxy aromatic acids
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Hydroxy aromatic acids are produced in high yields and high purity (>95%) from halogenated aromatic acids in a reaction mixture containing a copper source and a ligand that coordinates to copper.
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Page/Page column 20-21
(2008/06/13)
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- A convenient and regioselective oxidative bromination of electron-rich aromatic rings using potassium bromide and benzyltriphenylphosphonium peroxymonosulfate under nearly neutral reaction conditions
-
Regioselective oxidative bromination of electron-rich aromatic rings has been studied using potassium bromide as a bromine source in the presence of benzyltriphenylphosphonium peroxymonosulfate as oxidant under nearly neutral reaction conditions. In most cases we obtained monobrominated derivatives regioselectively and in good to high yields without the aid of strong acids.
- Adibi, Hadi,Hajipour, Abdol R.,Hashemi, Majid
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p. 1255 - 1259
(2007/10/03)
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- Bromination of some aromatic compounds with potassium bromide in the presence of benzyltriphenylphosphonium peroxodisulfate
-
A simple, efficient, and mild method for selective bromination of some activated aromatic compounds using potassium bromide in the presence of benzyltriphenylphosphonium peroxodisulfate in nonaqueous solution is reported. The results obtained revealed good to excellent selectivity between ortho and para positions of phenols and methoxyarenes. Copyright Taylor & Francis Group, LLC.
- Tajik, Hassan,Mohammadpoor-Baltork, Iraj,Albadi, Jalal
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p. 323 - 328
(2007/10/03)
-
- Enforcing periodic secondary structures in hybrid peptides: A novel hybrid foldamer containing periodic γ-turn motifs
-
This note describes the design, synthesis, and conformational studies of a novel hybrid foldamer that adopts a definite compact, three-dimensional structure determined by a combined effect of the special conformational properties of the foldamer constituents. The striking feature of this de novo designed foldamer is its ability to display periodic γ-turn conformations stabilized by intramolecular hydrogen bonds. Conformational investigations by single-crystal X-ray studies, solution-state NMR, and ab initio MO theory at the HF/6-31G* level strongly support the prevalence of γ-turn motifs in both the di- and tetrapeptide foldamers, which are presumably stabilized by bifurcated hydrogen bonds in the solid and solution states. The strategy disclosed herein for the construction of hybrid foldamers with periodic γ-turn motifs has the potential to significantly augment the conformational space available for foldamer design with diverse backbone structures and conformations.
- Baruah, Pranjal K.,Sreedevi,Gonnade, Rajesh,Ravindranathan, Sapna,Damodaran, Krishnan,Hofmann, Hans-Joerg,Sanjayan, Gangadhar J.
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p. 636 - 639
(2007/10/03)
-
- Regioselective aromatic electrophilic bromination with dioxane dibromide under solvent-free conditions
-
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)
-
- Regeneration of carbonyl compounds from oximes, semicarbazones and tosylhydrazones with calcium hypochlorite and moist montmorillonite K-10
-
Oximes, semicarbazones and tosylhydrazones are converted into the corresponding carbonyl compounds in the presence of calcium hypochlorite and moist montmorillonite K-10 under mild and heterogeneous conditions.
- Movassagh, Barahman,Dahaghin, Ebrahim
-
p. 1541 - 1543
(2007/10/03)
-
- Acyl derivatives of 2-aminobenzimidazole and their fungicide activity
-
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
-
p. 738 - 743
(2007/10/03)
-
- Macrophage scavenger receptor antagonists for use in the treatment of cardiovascular diseases
-
Salicylanilide derivatives which are macrophagescavenger receptor antagonists are provided. Methods of treating cardiovascular disease comprising administration of the present compounds are also provided. The present compounds inhibit lipid accumulation within macrophage-derived foam cells.
- -
-
-
- A kinetic study into the hydrolysis of the ochratoxins and analogues by carboxypeptidase A
-
The hydrolyses of the ochratoxins and analogues by carboxypeptidase A were assessed. This was done by measuring the amount of phenylalanine formed with liquid chromatography coupled to tandem electrospray mass spectrometry. The kinetic data of ochratoxin A, ochratoxin B, and the synthetic bromo-ochratoxin B were compared to the values of a number of synthesized structure analogues, namely, ochratoxin A methyl ester, ochratoxin B methyl ester, N-(2-hydroxybenzoyl)phenylalanine, N-(5-chloro-2-hydroxybenzoyl)phenylalanine, N-(5-bromo-2-hydroxybenzoyl)phenylalanine, and N-(5-fluoro-2-hydroxybenzoyl)phenylalanine. The halogen-containing analogues had lower turnovers than their des-halo analogues. There are no substantial differences in the kinetic data between the different halogen-containing analogues.
- Stander,Steyn,Van der Westhuizen,Payne
-
p. 302 - 304
(2007/10/03)
-
- Oxidation of aldehydes by sodium chlorite
-
Oxidation of aldehydes by sodium chlorite.Sodium chlorite is an efficient reagent for the oxidation of aldehydes to the corresponding acids.The reactions were carried out at room temperature in dichloromethane-acetic acid solution for all aldehydes except salicylaldehydes.We show that these compounds can be oxidized using a DMSO-sodium methanolate solution.Yields are good, even in the case of aromatic aldehydes with electron donating groups.
- Bayle, J. P.,Perez, F.,Courtieu, J.
-
p. 565 - 567
(2007/10/02)
-
- The Bromination of Salicylate Anions. Evidence for the Participation of the Ortho Carboxylate Group
-
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
-
p. 4468 - 4473
(2007/10/02)
-
- Use of Potassium Bromate: Bromination of Derivatives of Benzene
-
Bromination of various derivatives of benzene using potassium bromate under acidic condition has been discussed.
- Banerjee, Amalendu,Banerjee, Gopal Chandra,Adak, Mohini Mohan,Banerjee, Santa,Samaddar, Haraprasad
-
p. 985 - 988
(2007/10/02)
-
