- Use of fluorine kinetic isotope effects in the study of steric effects in nucleophilic aromatic substitution reactions
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Leaving group fluorine kinetic isotope effects (F KIEs) have been determined in order to probe the influence of steric effects on the mechanism of the nucleophilic aromatic substitution (S(N)Ar) reaction of 2,4- dinitrofluorobenzene (DNFB) with 2- and 4-m
- Persson, Jonas,Matsson, Olle
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- Reaction kinetics investigation of 1-fluoro-2,4-dinitrobenzene with substituted anilines in ethyl acetate-methanol mixtures using linear and nonlinear free energy relationships
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Aromatic nucleophilic substitution reaction of 1-fluoro-2,4-dinitrobenzene with para-substituted and meta-substituted anilines was kinetically investigated in the mixtures of ethyl acetate and methanol at room temperature. The correlation of second-order rate coefficients with Hammett's substituent constants yields a fairly linear straight line with negative slope in different mole fractions of ethyl acetate-methanol mixtures. The measured rate coefficients of the reaction demonstrated a dramatic variation in ethyl acetate-methanol mixtures with the increasing mole fraction of ethyl acetate. Linear free energy relationship (LFER) investigations confirm that polarity has a major effect on the reaction rate whereas the hydrogen-bonding ability of the media has a slight effect on it. Nonlinear free energy relationship based on preferential solvation hypothesis showed differences between the microsphere solvation of the solute and the bulk composition of the solvents, and non-ideal behavior is observed in the trend of the rate coefficients, which cover the LFER results. Copyright
- Jamali-Paghaleh, Javad,Harifi-Mood, Ali Reza,Gholami, Mohammad Reza
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- “Zero VOC” Synthetic Strategy – Aromatic Amination Reactions in Deep Eutectic Solvents
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Rising concern for environment hazards resulting from the use of volatile organic compounds (VOCs) is prompting many chemists to use “green” solvents like water, polyethylene glycol, ionic liquids and deep eutectic solvents (DES). With a few notable exceptions, many of these processes still need to use volatile organic solvents for the workup and isolation of products. In the present report, we demonstrate a “zero VOC” protocol which eliminates the need to use organic solvents for any stage of the reaction. As a proof of concept, nucleophilic aromatic substitution reactions of 1-halo-2,4-dinitrobenzene with secondary amines were carried out in deep eutectic solvents. The reaction workup involved the addition of water for separating the product from the DES. Evaporation of water led to recovery of the DES, which exhibited good recyclability. The reaction in deep eutectic solvents was much faster than that in many other solvents, as confirmed by the kinetic studies. An attempt was made to elucidate the origin of this rate enhancement based on analysis activation parameters and correlation with the polarity parameters. The results show that use of deep eutectic solvents can take chemists a step closer towards the “zero VOC” synthetic strategy.
- Valvi, Arun,Tiwari, Shraeddha
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- Effects of the nucleophile structure on the mechanisms of reaction of 1-chloro-2,4-dinitrobenzene with aromatic amines in aprotic solvents
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The kinetics of reactions of 1-chloro-2,4-dinitrobenzene with aniline and several substituted aromatic amines, B, in toluene shows a quadratic dependence of the second-order rate constant, kA, on [B], which is preserved even in the presence of increasing amounts of dimethylaniline, while the reaction with N-methylaniline shows a linear dependence of kA vs [B]. All these results are interpreted by the "dimer nucleophile" mechanism, and confirmed by the effects of a non-nucleophilic hydrogen bond acceptor tertiary amine which show the relevance of the structure of the nucleophile and the role of mixed aggregates in defining the mechanisms of aromatic nucleophilic substitutions with amines in aprotic solvents.
- Nudelman, Norma Sbarbati,Silvana Alvaro, Cecilia E.,Savini, Monica,Nicotra, Viviana,Yankelevich, Jeannette
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- Benzimidazole diamine monomer and preparation method thereof
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The invention relates to a benzimidazole diamine monomer and a preparation method thereof. The preparation method comprises the steps that a benzimidazole intermediate with the structural formula shown in the formula (III) is reduced, a reduction product of the benzimidazole intermediate is mixed with a compound with the structural formula shown in the formula (IV), a substitution reaction and a reduction reaction are conducted in sequence, and the benzimidazole diamine monomer is obtained; the benzimidazole intermediate with the structural formula as shown in the formula (III) is prepared byfirstly carrying out partial reduction reaction on a compound with the structural formula as shown in the formula (I), then a partial reduction product of the compound is mixed with a compound with the structural formula as shown in the formula (II), and then the substitution reaction and a cyclization reaction are sequentially carried out. The structural formulas of the formula (I), the formula (II), the formula (III) and the formula (IV) are shown in the specification. The preparation method is simple and feasible, the prepared benzimidazole diamine monomer is used for preparing polyimide, and the heat resistance and solubility of polyimide can be improved.
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Paragraph 0068-0071; 0079-0082; 0090-0093
(2020/07/21)
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- Deep eutectic solvent as an operative media on structure-reactivity relationships
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Deep eutectic solvents seem to be environmentally friendly solvents, particularly because they are prepared easily and have very low-vapor pressures under ambient conditions. They are suitable candidates as green solvents for reaction media with special properties. To present this behavior, substitution reactions of some para- and meta-substituted anilines with 1-fluoro-2,4-dinitrobenzene have been spectrophotometrically investigated in varying mole fractions of ethaline as a deep eutectic solvent in dimethyl sulfoxide (DMSO). The measured rate coefficients of the reaction demonstrated a noticeable variation with the increasing mole fraction of ethaline in ethaline-DMSO mixtures. The linear free energy relationship (LFER) of second-order rate coefficients based on Hammett's substituent constants demonstrates a reasonably linear straight line with a negative slope in different mole fractions of ethaline-DMSO mixtures. Another LFER investigation based on the polarity parameters of the media showed a good agreement with hydrogen bond donor and acceptor abilities of the solvent. Non-LFER assay according to the preferential solvation model confirmed differences between the microsphere solvation of the solute molecules and the bulk composition of the solvents.
- Harifi-Mood, Ali Reza,Khorshahi, Hasan
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p. 511 - 519
(2019/04/14)
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- Oxidative arylamination of 1,3-dinitrobenzene and 3-nitropyridine under anaerobic conditions: The dual role of the nitroarenes
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1,3-Dinitrobenzene and 3-nitropyridine react with lithium arylamides under anaerobic conditions to produce N-aryl-2,4-dinitroanilines and N-aryl-5-nitropyridin-2-amines, respectively, in 8-42% yields. ARKAT-USA, Inc.
- Gulevskaya, Anna V.,Tyaglivaya, Inna N.,Verbeeck, Stefan,Maes, Bert U.W.,Tkachuk, Anna V.
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experimental part
p. 238 - 251
(2011/08/22)
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- Novel benzimidazole-based MCH R1 antagonists
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The identification of an MCH R1 antagonist screening hit led to the optimization of a class of benzimidazole-based MCH R1 antagonists. Structure-activity relationships and efforts to optimize pharmacokinetic properties are detailed along with the demonstration of the effectiveness of an MCH R1 antagonist in an animal model of obesity.
- Carpenter, Andrew J.,Al-Barazanji, Kamal A.,Barvian, Kevin K.,Bishop, Michael J.,Britt, Christy S.,Cooper, Joel P.,Goetz, Aaron S.,Grizzle, Mary K.,Hertzog, Donald L.,Ignar, Diane M.,Morgan, Ronda O.,Peckham, Gregory E.,Speake, Jason D.,Swain, Will R.
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p. 4994 - 5000
(2007/10/03)
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- Triphendioxazine compounds
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The triphendioxazine compounds of the general formula (I) in which the rings labeled A in positions 1,2-, 2,3- or 3,4- and 8,9-, 9,10- or 10,11- carry a linearly or angularly fused heterocyclic ring containing at least one nitrogen atom which is substitut
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- Triphendioxazine compounds
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The triphendioxazine compounds of the general formula (I) in which the rings labelled A in positions 1,2-, 2,3- or 3,4- and 8,9-, 9,10- or 10,11- carry a linearly or angularly fused heterocyclic ring containing at least one nitrogen atom which is substitu
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- KINETICS OF THE REACTION OF 2-(2,4-DINITROPHENOXY)-N-ETHYLPYRIDINIUM TETRAPHENYLBORATE WITH AROMATIC AMINES IN ACETONITRILE
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The reactions of 2-(2,4-dinitrophenoxy)-N-ethylpyridinium salts with arylamines take place by nucleophilic substitution at a carbon atom of the benzene ring with the formation of 2,4-dinitrodiphenylamine derivatives.The sensitivity coefficient (ρ0) to the induction effect of the substituents in the arylamine does not depend on the temperature in the range of 10-55 deg C and is equal to -6.89.The constant of the leaving group (τAr) for the 2-hydroxy-N-ethylpyridinium cation amounts to 1.66.
- Titskii, G. D.,Mitchenko, E. S.,Dubovaya, A. A.
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p. 1945 - 1949
(2007/10/02)
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- Kinetic study and analytical application of the hexadecyltrimethylammonium bromide-catalyzed reaction of 1-fluoro-2,4-dinitrobenzene with amines
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Arylation of amines by reaction with 1-fluoro-2,4-dinitrobenzene is catalyzed by micelles of cetrimonium bromide. This catalysis has been exploited to reduce the analysis time in the spectrophotometric determination of amines as their dinitrophenyl derivatives. The kinetics of the catalysis were studied for the five amines: alanine, phenylalanine, aniline, 4-methylaniline, and 4-methoxyaniline. The dependence of rate constant on surfactant concentration can be quantitatively accounted for by Berezin's model, in which uptake of the amine and the 1-fluoro-2,4-dinitrobenzene by the micelle is described as a partitioning phenomenon for both species. An alternative model is developed in which one reactant partitions into the micellar phase and the other binds to the micelle with 1:1 stoichiometry; the two models are formally equivalent. Intrinsic catalytic rate constants and binding constants were evaluated. About one-third to one-half of the maximum observed micellar acceleration is attributed to a true micellar catalysis, the remainder being ascribed to an increase in local reactant concentrations in the micelle.
- Wong,Connors
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p. 146 - 150
(2007/10/02)
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- REACTIONS BETWEEN 1-HALOGENO-2,4-DINITROBENZENES AND SUBSTITUTED ANILINES: KINETICS AND EVIDENCE FOR THE PRESENCE OF A MOLECULAR COMPLEX
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The title reactions (halogen = F or Cl) have been studied in benzene and in chloroform.The experimental reaction order in aniline is higher than 2 in every case (the value 3 is reached for the fluoro derivative in both solvents).Spectroscopic evidence (1H NMR and UV) indicates the presence of a molecular complex the formation of which (together with a base-catalysed step) is probably responsible for the observed kinetic features.The substituent effect (in aniline) is discussed.
- Forlani, Luciano
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p. 205 - 212
(2007/10/02)
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