- Ag/SiO2: A novel catalyst with high activity and selectivity for hydrogenation of chloronitrobenzenes
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Ag/SiO2 prepared by an in situ reduction method are found, for the first time, to be highly effective and recyclable catalysts for the selective hydrogenation of a range of chloronitrobenzes to their corresponding chloroanilines, which are of great potential as industrially viable and cheap novel catalysts for the production of chloroanilines. The Royal Society of Chemistry 2005.
- Chen, Yangying,Wang, Chuang,Liu, Hongyang,Qiu, Jieshan,Bao, Xinhe
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- NEW INSIGTHS on the KINETICS and MECHANISM of the ELECTROCHEMICAL OXIDATION of DICLOFENAC in NEUTRAL AQUEOUS MEDIUM
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The diclofenac (DCF) electrochemical oxidation mechanism was studied through: linear voltammetry (LV), chronoamperometry (CA) sampled-current voltammetry (SCV), potentiostatic coulometry (PC) cyclic voltammetry (CV) under stagnant conditions and linear voltammetry under forced convection conditions (FCLV) over a carbon paste electrode (CPE) from an aqueous medium containing 0.1 M phosphate buffer at pH 7. It was found that the DCF electrochemical oxidation involves an EC mechanism, where the electrochemical reaction is carried out through a one electron-exchange while the chemical reaction involves breaking up the DCF through the nitrogen atom, thereby generating the fragments 2,6 dichloroaniline and 2-(2hydroxyprop-2-enyl)phenol. Reverting the potential scan in the cathodic direction at different scan rates and regardless of its rate, after the oxidation peak, it was found that it was possible to reduce only 38% of the DCF oxidized. The spectrophotometric study carried out during different macro-electrolysis periods allowed observing that the current decrease of the oxidation peak coupled to the DCF absorption (at 270 nm), together with the development of a new spectrophotometric absorption maximum (450 nm), all confirm the EC mechanism proposed. With the use of several experimental techniques (CA, LV and FCLV) and theoretical ones using the Stokes-Einstein approach, the DCF diffusion coefficient was determined, this being in average 8.1 × 10-6 cm2 s-1.
- Cid-Cerón,Guzmán-Hernández,Ramírez-Silva,Galano,Romero-Romo,Palomar-Pardavé
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Read Online
- Method for preparing dichloroaniline through chlorination
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The invention relates to a method for preparing dichloroaniline by chlorination. The method comprises the following steps: adding o-chloroaniline into a solvent, and carrying out chlorination reactionat 0-80 DEG C for 2-12 hours; neutralizing the reaction solution with alkali until the pH value is 9-10, and separating the organic phase from the water phase to obtain an organic phase; and carryingout rectification separation on the organic phase to respectively obtain pure products 2,4-dichloroaniline and 2,6-dichloroaniline. According to the invention, the main raw material o-chloroaniline is easy to obtain and low in price, so that the method has relatively high economical efficiency; the method has the advantages of no need of special reagents or solvents, one-step chlorination reaction, mild reaction conditions, simple operation, less wastewater, simple treatment and environmental friendliness, and only generates a small amount of salt-containing wastewater in the neutralization step; and the total yield is greater than 90%, and the purity can reach 99.5% or above, which is higher than the purity of 99% of the product in the prior art.
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Paragraph 0027-0040
(2021/02/13)
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- Hydrodebromination of Aromatic Bromides Catalyzed by Unsupported Nanoporous Gold: Heterolytic Cleavage of Hydrogen Molecule
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Unsupported nanoporous gold (AuNPore) is a highly efficient, practically applicable, and recyclable catalyst for hydrodebromination of aromatic bromides. The AuNPore-catalyzed hydrodebromination of aromatic bromides proceeded smoothly at relatively low hydrogen pressure and temperature to achieve good to excellent yields of the corresponding non-bromine variants. The selective hydrodebromination reaction occurred exclusively in the coexistence of chlorine atom. For the first time, a mechanistic study revealed that the H?H bond splits in a heterolysis manner on the surface of AuNPore to generate Au?H hydride species.
- Bao, Ming,Feng, Xiujuan,Yamamoto, Yoshinori,Zhang, Sheng,Zhao, Yuhui
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p. 4951 - 4957
(2020/09/09)
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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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- Method for synthesizing 2,6-dichloroaniline at low cost
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The invention discloses a method for synthesizing 2,6-dichloroaniline at low cost, which comprises the following steps: preparing N,N-diphenyl urea from aniline, urea, a solvent and a catalyst; then preparing a 1,3-diphenyl urea sulfonyl chloride mixed solution by using a chlorosulfonic acid non-sulfonating agent and using N,N-diphenyl urea as a reaction raw material; feeding chlorine into the reaction system, and carrying out a chlorination reaction to prepare 3,5-dichloro-4-aminobenzenesulfonyl chloride; and finally, carrying out evaporative hydrolysis reaction to obtain the target product 2,6-dichloroaniline. The method is low in raw material cost and high in target yield, and sulfuric acid can be recycled.
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Paragraph 0023; 0029; 0030; 0036; 0037; 0043; 0044; 0050
(2020/05/30)
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- Staudinger reaction using 2,6-dichlorophenyl azide derivatives for robust aza-ylide formation applicable to bioconjugation in living cells
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Efficient formation of water- and air-stable aza-ylides has been achieved using the Staudinger reaction between electron-deficient aromatic azides such as 2,6-dichlorophenyl azide and triarylphosphines. The reaction proceeds rapidly and has been successfully applied to chemical modification of proteins in living cells.
- Meguro, Tomohiro,Terashima, Norikazu,Ito, Harumi,Koike, Yuka,Kii, Isao,Yoshida, Suguru,Hosoya, Takamitsu
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supporting information
p. 7904 - 7907
(2018/07/25)
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- Electron transfer-induced reduction of organic halides with amines
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Reduction of a variety of organo halides was examined by using amines as a sacrificial hydrogen source. UV light-induced reduction of vinyl and aryl halides with triethylamine proceeded smoothly to give the corresponding reduced products. High temperature heating also caused the reduction and DABCO (1,4-diazabicyclo[2.2.2]octane) also served as a good reducing reagent.
- Fukuyama, Takahide,Fujita, Yuki,Miyoshi, Hayato,Ryu, Ilhyong,Kao, Shih-Chieh,Wu, Yen-Ku
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supporting information
p. 5582 - 5585
(2018/06/04)
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- Preparation of aniline derivatives
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In the present invention, provided is a novel manufacturing method of aniline derivative, which is more simple and eco-friendly and takes less cost compared with an existing synthesizing aniline method, comprising a step of manufacturing chemical formula 1 by making chemical formula 2 react with chemical formula 3 under catalyst, bases and solvents wherein the manufacturing method aniline derivative is manufactured through one pot in a simple manner and accordingly easily removes the solvent with use of distillation under reduced pressure after reaction.
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Paragraph 0087-0092
(2016/10/08)
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- Simultaneous identification of Fenton degradation by-products of diclofenac, ibuprofen and ketoprofen in aquatic media by comprehensive two-dimensional gas chromatography coupled with mass spectrometry
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Diclofenac, ibuprofen and ketoprofen are anti-inflammatory drugs intensively used both in human and animal treatment. Due to their high stability these compounds are partially removed by wastewater treatment plants and from this reason the development of some alternative treatments such as advanced oxidative processes are necessary. The main problems in the optimization of an advanced oxidative process rise from the difficulties which appear in the identification of degradation by-products necessary for the establishment of degradation pathway. In this paper a developed method for the simultaneous identification of Fenton degradation by-products of the three above mentioned pharmaceuticals is presented. The obtained results show the comprehensive two-dimensional gas chromatography coupled with mass spectrometry as a proper method for the analysis of the complex mixture of compounds resulted from the Fenton degradation process. Moreover, some compounds never mentioned in the scientific literature were identified. (Chemical Equation Presented).
- Beldean-Galea, Mihail Simion,Coman, Virginia,Copaciu, Florina,Thiébaut, Didier,Vial, Jér?me
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p. 1021 - 1027
(2015/07/15)
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- One-pot conversion of phenols to anilines via Smiles rearrangement
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A convenient one-pot synthesis of phenols to anilines using 2-chloroacetamide/K2CO3/DMF system catalyzed by KI via Smiles rearrangement has been described. The synthesis of extensive amino aromatic products from phenols containing electron withdrawing group, has been performed in moderate to excellent yields to demonstrate the potentiality of this method in bio-medicinal and pharmaceutical applications.
- Xie, Yong-Sheng,Vijaykumar,Jang, Kiwan,Shin, Hong-Hyun,Zuo, Hua,Shin, Dong-Soo
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p. 5151 - 5154
(2013/09/02)
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- Catalytic transfer hydrogenation of aromatic nitro compounds by employing ammonium formate and 5% platinum on carbon
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Aromatic nitro compounds were reduced to respective amines in high yields by using 5% platinum on carbon with ammonium formate or formic acid as hydrogen donor. It was observed that the former was mote efficient donor than the later. Further we have found that reduction of nitro groups occurs without hydrogenolysis of halogens and the reducible substituents which remains unchanged under the reaction conditions.
- Gowda,Mahesh
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p. 3639 - 3644
(2007/10/03)
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- Oxidative chlorination, desulphonation, or decarboxylation to synthesize pharmaceutical intermediates: 2,6-Dichlorotoluene, 2,6-dichloroaniline, and 2,6-dichlorophenol
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An alternative manufacturing process scheme was developed for 2,6-dichlorotoluene, 2,6-dichloroaniline, and 2,6-dichlorophenol, involving oxidative chlorination after protection of the starting material in the para position followed by deprotection involving desulphonation or decarboxylation. Oxidative chlorination of 4-methylbenzenesulphonic acid, 4-methylbenzoic acid, 4-aminobenzoic acid, and 4-hydroxybenzoic acid by using HCl-H2O2, and their subsequent desulphonation or decarboxylation, gave a 60-75% yield of the desired product.
- Mukhopadhyay,Chandalia
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- Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCI (HBr) Acetonitrile Reagent
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Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60 °C) with excellent to moderate yields.
- Liu, Lilian Kao,Lin, Ching-Shan
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- Halide ion trapping of nitrenium ions formed in the Bamberger rearrangement of N-arylhydroxylamines. Lifetime of the parent phenylnitrenium ion in water
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The data of p-aminophenol, the product of Bamberger rearrangement, Were analyzed by a mechanism involving rate-limiting formation of the appropriate arylnitrenium ion followed by product-determining steps in involving trapping by the solvent or by the added halide. The possibility that a portion of the halide-trapped products were derived from a pre-association mechanism was also include. Kinetic analyses then produced kBr:kw and kCl:kw ratios for two limiting cases, one involving pre-association with an equilibrium constant Kas = 0.3, and one ignoring pre-association. From an azide:water ratio (kAz:kw) previously determined for the 2,6-dimethylphenylnitrenium, kBr was concluded to lie in the range (4-5) × 109 M-1 s-1 for all of the nitrenium ions of this study. This range for kBr then led to kw values of (1-2) × 109 s-1 (2,5-Me2), (2-3) × 109 s-1 (2-Me), and (4-8) × 109 s-1 (parent and 2-Cl), where the ranges reflect uncertainties in the exact value of kBr and in the contribution from pre-association. The lifetime of the parent phenylnitrenium ion in water at one molar ionic strength is concluded to lie in the range 125-250 ps.
- Fishbein,McClelland
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p. 1321 - 1328
(2007/10/03)
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- Process for preparing amines
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Process for preparing amines by reacting amides in aqueous-alkaline solutions and/or suspensions with halogens or hypohalites in the presence of alcohols, and converting the reaction products into the amines by hydrolysis, hydrogenation or reductive methods.
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- Method of preparing substituted malonic ester anilides and malonic acid mono-anilides
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Malonic mono-ester mono-anilides and malonic acid mono-anilides and bis-anilides are produced by reaction of malonic acid di-alkyl esters with an aniline in the presence of a stoichiometric amount, based on the aniline, of an alkali alcoholate, accompanied by the initial formation of alkali salts of mono-ester mono-anilides or malonic-acid bis-anilides. Neutralization results in the formation of free malonic mono-ester mono-anilide or malonic-acid bis-anilide and saponification forms the malonic acid mono-anilide. Chloro-substituted anilides of cyclopropyl-1,1-dicarboxylic acid and their mono-esters are preferred.
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- Synthesis of 2,6-disubstituted and 2,3,6-trisubstituted anilines
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A number of 2,6-disubstituted and 2,3,6-trisubstituted anilines have been prepared via the selective para dehalogenation of the corresponding anilines. Modification of the substituents on the amino nitrogen demonstrates that the selectivity is derived from steric rather than electronic effects. The effects of the choice of formate hydrogen donor, Pd catalyst, solvent, and temperature upon the efficiency and selectivity of the dehalogenation are discussed.
- Pews,Hunter,Wehrmeyer
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p. 4809 - 4820
(2007/10/02)
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- Process for the preparation of 2,4- or 2,6-dihalogeno-aniline
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2,4- or 2,6-dihalogeno-aniline can be prepared by reacting an amino-benzoic acid ester of the formula STR1 in which R1, R2 and R3 have the meanings indicated in the description, with 2-2.5 moles of a chlorinating or brominating agent in an inert reaction medium at a temperature of 40°-160° C. and subsequently hydrolyzing and decarboxylating the dihalogenated amino-benzoic acid ester.
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- A novel synthesis of 2,6-disubstituted and 2,3,6-trisubstituted anilines
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2,6-Disubstituted and 2,3,6-trisubstituted anilines have been synthesized by a four-step approachy involving the selective reduction of a para halogen of the diacetanilide derivatives utilizing a palladium-on-carbon catalyst and formic acid salts as the in situ hydrogen donor.
- Pews,Hunter,Wehmeyer
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p. 7191 - 7194
(2007/10/02)
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- Direct determination of chlorination products of organic amines using membrane introduction mass spectrometry
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Direct analysis of organic chloramines in low concentrations in aqueous solutions is achieved by membrane introduction mass spectrometry. Tandem mass spectrometry allows structures of the chlorination products to be determined and shows that nitrogen chlorination occurs for aliphatic amines and ring chlorination for aniline. Monochlorination of aniline occurs mainly at the ortho position, while dichlorination yields 20-35% diortho and 80-65% ortho-para substitution products. Depending on the reaction conditions, the actual chlorination reagent can be chloramine, hypochlorous acid, and possibly chlorine. The high ortho chlorination yields of aniline are explained by a mechanism in which chlorination occurs first at the nitrogen atom with subsequent intramolecular rearrangement to the ortho position in analogy to rearrangement of the nitro group in N-nitro aromatic amines. Using flow injection analysis procedures, it is possible to follow in an on-line fashion reactions that yield (or remove) organic chloramines at sub parts per million levels.
- Kotiaho,Hayward,Cooks
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p. 1794 - 1801
(2007/10/02)
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- Magnetic susceptibilities of organic compounds: Part V - Influence of substituents on diamagnetic susceptibilities of disubstituted and trisubstituted benzenes
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The magnetic susceptibilities of a number of triads of isomeric disubstituted benzenes have been determined, choosing the compounds in such a way that the substituents are present in the following combinations: (i) two electron-releasing substituents, (ii) a halogeno and an electron-releasing substituent, (iii) a halogeno and an electron-attracting substituent, and (iv) two halogeno substituents.The data show that for types (i), (ii) and (iv), the ortho isomers have the highest magnetic susceptibilities, the susceptibilities decreasing in the order: ortho > meta > para; for type (iii), the meta-isomers have the highest susceptibilities, the susceptibilities decreasing in the order: meta > para > ortho.The diamagnetic susceptibilities of some isomeric trisubstituted benzenes have also been determined and the data reveal that the susceptibility is the highest where the crowding of substituents is the highest (1,2,3-isomer) and lowest where the substituents are staggered and least crowded (1,3,5-isomer).Another observation made in the case of trisubstituted benzene is the applicability of a principle of additivity of their diamagnetic susceptibilities.
- Baliah, V.,Jeyanthy, J. Judith Diana
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p. 472 - 476
(2007/10/02)
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- 3-amino-5-methyl-1H-pyrazole-4-carboxylic acids and esters thereof as anticonvulsants, muscle relaxants and anxiolytics
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A novel method of controlling epilepsy, muscle tension, muscular spasticity, and anxiety in living animal bodies by administering compounds of the formula: STR1 wherein: R1 is hydrogen, loweralkyl or a pharmaceutically acceptable cation; R2 and R3, same or different, are hydrogen, loweralkyl, aryl, cycloalkyl, loweralkenyl, 1-adamantyl, heterocyclicaminoalkyl, diloweralkylaminoloweralkyl, or R2 with R3 and adjacent nitrogen may form a heterocyclic ring structure; and the pharmaceutical acceptable acid salts, and tautomeric isomers thereof; and novel pharmaceutical compositions therefor are disclosed.
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- The Thermolysis of Polyazapentadienes. Part 4. Formation of Indoles and Quinoxalines from 5-(2,6-Disubstituted phenyl)-1,2,5-triazapentadienes and Related Compounds
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7-Methylindole and 5-substituted quinoxalines are the principal cyclised products from the qas-phase thermolyses of the hydrazones (2) and (5) and the oxime ester (7).Both heterocyclic systems arise by competitive decomposition of the spirodienyl radical, e.g. (18), the indole by loss of MeCN and a hydrogen atom, and the quinoxalines by loss of a methyl radical.
- McNab, Hamish
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p. 377 - 380
(2007/10/02)
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- Novel Reactions: Part I - Facile Synthesis of Substituted ortho-Chloranilines from Nitrobenzene Derivatives
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N-Substituted benzo and acetohydroxamic acids (5), prepared from N-arylhydroxylamines and benzoyl or acetyl chloride, react readily with thionyl chloride at low temperature to give ortho-chloroanilide derivatives (6) in good yield.The latter (6) on hydrolysis give ortho-chloroanilines (10).Since the N-arylhydroxylamines are obtained from nitroarenes by partial reduction, the overall reaction amounts to the preparation of 10 from nitroarenes.
- Ayyangar, N. R.,Kalkote, U. R.,Nikrad, P. V.
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p. 872 - 877
(2007/10/02)
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- INSECT CHITIN FORMATION INHIBITORS. PART I. SYNTHESIS OF 1-(2,6-DICHLOROBENZOYL)-3-(2,4,6-TRICHLOROPHENYL)-UREA
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The synthesis of the title compound, obtained for investigations on its activity as the insect chitin formation inhibitor,is described.
- Biernacki, Wladyslaw,Gdula, Andrzej
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p. 451 - 454
(2007/10/02)
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