- Molecular recognition-based catalysis in nucleophilic aromatic substitution: A mechanistic study
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Nucleophilic aromatic substitution for nitro-activated substrates in the presence of glymes and crown ethers is reported. The kinetic study reveals the many-sided nature of the polyether-catalyzed SNAr mechanism as well as the main features aff
- Basilio, Nuno,Garcia-Rio, Luis,Pena-Gallego, Angeles,Perez-Lorenzo, Moises
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- Reactions of Primary Amines with 2,4-Dinitrochlorobenzene in Microemulsions
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Reactions of 2,4-dinitrochlorobenzene with n-butyl, n-amyl, and n-hexylamine have been examined in microemulsions of n-octane and cetyltrimethylammonium bromide (CTABr) or sodium dodecul sulfate (SDS) with amine as cosurfactant.The second-order rate const
- Athanassakis, Vassilios,Bunton, Clifford A.,Buzzaccarini, de Francesco
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- Characterization of solvent mixtures. Part 8 - Preferential solvation of chemical probes in binary solvent systems of a polar aprotic hydrogen-bond acceptor solvent with acetonitrile or nitromethane. Solvent effects on aromatic nucleophilic substitution r
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The use of chemical probes for the characterization of chemical properties was explored for completely non-aqueous aprotic binary solvent mixtures. The Dimroth-Reichardt ET(30) betaine dye, 4-nitrophenol, 4-nitroanisole, 4-nitroaniline and N,N-
- Mancini,Terenzani,Adam,Pérez,Vottero
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- Kinetic Study of the Reaction of N-(2,4-Dinitrophenyl)imidazole with Piperidine and n-Butylamine
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The reaction of N-(2,4-dinitrophenyl)imidazole, 1, with piperidine and n-butylamine was studied.The reaction with piperidine is catalyzed by hydroxide ions and by the amine while the reaction with n-butylamine is weakly catalyzed by hydroxide ion.The hydrolysis of the substrate competes with the aminolysis reaction.The base catalysis in the reaction of 1 with piperidine is shown to be a consequence of rate-limiting deprotonation of the zwitterionic intermediate complex, followed by spontaneous (noncatalyzed) leaving group expulsion.On the other hand, the small rateacelaration observed in the reaction of butylamine as well as the catalysis of the hydrolysis reaction by n-butylamine and piperidine is considered of unclear origin.
- Vargas, Elba B. de,Rossi, Rita H. de
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- Catalysis in Micellar Media. Kinetics and Mechanism for the Reaction of 1-Fluoro-2,4-dinitrobenzene with n-Butylamine and Piperidine in n-Hexane and AOT/n-Hexane/Water Reverse Micelles
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The nucleophilic aromatic substitution SNAr reaction of 1-fluoro-2,4-dinitrobenzene with n-butylamine and piperidine was studied in n-hexane and AOT/n-hexane/water reverse micelle media. The kinetic profile of the reactions was investigated as
- Correa, N. Mariano,Durantini, Edgardo N.,Silber, Juana J.
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- Catalysis by Cyclodextrins in Nucleophilic Aromatic Substitution Reactions. 2. Amines as Nucleophiles
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The kinetics of the reactions of 1-chloro-2,4-dinitrobenzene and 1-fluoro-2,4-dinitrobenzene with piperidine, butylamine, and morpholine in the presence of β-cyclodextrin (CD) was studied.There is an increase in the observed rate constant for the reactions of the first two amines at pH AH when CD is added, but there is no change in the rate for these two reactions at pH > pKAH and for the reaction of morpholine either at pH AH or at pH > pKAH.The three amines (A) as well as their conjugated acids (AH) form inclusion complexes with the CD.The association equilibrium constants for the amines are 50.3, and 17 M-1 for piperidine, butylamine, and morpholine, respectively.Part of the observed catalysis is attributed to the fact that the amines and the complexed amines (ACD) react with the substrate at similar rates and at constant pH, the ratio (A + ACD)/(AH + AHCD) increases with the concentration of CD.Besides that, the complexed substrates react with the complexed amines at faster rates than that of the free substrate with the free amine.The latter reaction is not detected in the reactions at high pH and in the reactions of morpholine.
- Barra, Monica,Rossi, Rita H. de,Vargas, Elba B. de
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- Direct formation of aromatic C-N bonds. Regioselective amination of m- dinitrobenzene via fluoride promoted nucleophilic aromatic photosubstitution for hydrogen
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Useful yields are achieved in the regioselective direct formation of anilines and aromatic amides through hydrogen nucleophilic aromatic photosubstitution of m-dinitrobenzene with primary amines and amides, promoted by fluoride anion.
- Huertas, Inma,Gallardo, Iluminada,Marquet, Jordi
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- Solvent effects on chemical processes: New solvents designed on the basis of the molecular-microscopic properties of (molecular solvent + 1,3-dialkylimidazolium) binary mixtures
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The purpose of this work was to analyze the microscopic feature of binary solvent systems formed by a molecular solvent (acetonitrile or dimethylformamide or methanol) and an ionic liquid (IL) cosolvent [1-(1-butyl)-3- methylimidazolium tetrafluoroborate
- Mancini,Fortunato,Adam,Vottero
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- Photoacoustic Spectroscopy of Chemically Bonded Chromatographic Stationary Phases
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A qualitative study of chemically-bonded, chromatographic stationary phases was undertaken to assess the applicability of photoacoustic spectroscopy (PAS) to the characterization of chemically-modified surfaces.The ability of this technique to identify co
- Lochmueller, C. H.,Marshall, S. F.,Wilder, D. R.
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- Direct coupling of nucleophiles with nitroaromatic compounds via fluoride-promoted oxidative nucleophilic aromatic substitution for hydrogen
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Useful yields are achieved in the regioselective direct coupling of amines, amides, and ketones with m-dinitrobenzene, 1-nitronaphthalene, and 1,3-dinitronaphthalene, through oxidatively activated nucleophilic aromatic substitution for hydrogen promoted by fluoride anions.
- Huertas, Inma,Gallardo, Iluminada,Marquet, Jordi
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- Mechanism of base catalysis in the reactions of phenyl aryl ethers with aliphatic amines in dimethyl sulfoxide
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The reactions of n-butylamine, pyrrolidine and piperidine with phenyl 2,4,6-trinitrophenyl ether, 3, in DMSO result in the rapid reversible formation of adducts by reaction at the 3-position followed by attack at the 1-position leading to substitution of
- Chamberlin, Rachel A.,Crampton, Michael R.
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- Flavin mimetics: Synthesis and photophysical properties
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We report the synthesis of new isoalloxazines using a microwave-assisted approach to make N-substituted-2-nitroanilines followed by one-pot reduction and condensation via Hemmerich's method. The influence of substituents on positions 7, 8, and 10 of flavin core on the optical properties is investigated. The aliphatic functionalities on N10 give rise to quantum yields of 0.7, while aromatic side-chains quench fluorescence. Relaxed geometries (DFT) of chiral and achiral derivatives have been used for TD-DFT calculations, which yielded good agreement with the experimental UV and CD data.
- R?s?dean, Dora-M.,Machida, Takashi,Sada, Kazuki,Pudney, Christopher R.,Panto?, G. Dan
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- Aryl-Diadamantyl Phosphine Ligands in Palladium-Catalyzed Cross-Coupling Reactions: Synthesis, Structural Analysis, and Application
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Synthesis, temperature-dependent NMR structure investigation and utilization of a new, stable and easily accessible aryl-diadamantylphosphine ligand family is reported. The bulky and electron-rich phosphorus center of the ligand enhances the catalytic activity of palladium in cross-coupling reactions of sterically demanding ortho-substituted aryl halides. In our study, we demonstrated the synthetic applicability of the new phosphine ligands in Buchwald-Hartwig and tosyl hydrazone coupling reactions.
- Sinai, ádám,Simkó, Dániel Cs.,Szabó, Fruzsina,Paczal, Attila,Gáti, Tamás,Bényei, Attila,Novák, Zoltán,Kotschy, András
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supporting information
p. 1122 - 1128
(2020/03/03)
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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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p. 4933 - 4939
(2018/09/11)
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- Pd(OAc)2-catalyzed dinitration reaction of aromatic amines
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Taking advantage of Pd(OAc)2-catalyzed dinitration reactions with Bi(NO3)3·5H2O in trifluoroethanol (TFE) and trifluoroacetic acid (TFA), we have developed an efficient and practical method for the synthesis of secondary dinitro-aromatic amines. The products could be applied to the preparation of 5-amine-N-methyl-benzimidazolone, the azo-dyes, economic advantages. The method has also been expanded to the dinitration reaction of some tertiary aromatic amines.
- Feng, Yi-Si,Mao, Long,Bu, Xiao-Song,Dai, Jian-Jun,Xu, Hua-Jian
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p. 3827 - 3832
(2015/06/02)
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- N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate as a highly active and selective esterification catalyst
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N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate (1) was found to be a very active esterification catalyst that promotes condensation of equal mole amount of carboxylic acids and alcohols under mild conditions. This catalyst is also highly selective towards carboxylic acid and alcohol substrates at ambient temperature.
- Sattenapally, Narsimha,Wang, Wei,Liu, Huimin,Gao, Yong
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supporting information
p. 6665 - 6668
(2013/11/19)
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- Mechanistic assessment of SNAr displacement of halides from 1-Halo-2,4-dinitrobenzenes by selected primary and secondary amines: Br?nsted and Mayr analyses
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Pseudo-first-order rate constants (kobsd) have been measured spectrophotometrically for nucleophilic substitution reactions of 1-X-2,4-dinitrobenzenes (1a-d, X = F, Cl, Br, I) with various primary and secondary amines in MeCN and H2O
- Um, Ik-Hwan,Im, Li-Ra,Kang, Ji-Sun,Bursey, Samantha S.,Dust, Julian M.
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supporting information
p. 9738 - 9746
(2013/01/15)
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- ONSH: Optimization of oxidative alkylamination reactions through study of the reaction mechanism
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(Figure presented) Oxidative alkylamination of electron-deficient (hetero)aromatic compounds, via the nucleophilic substitution of hydrogen, is a methodology that has made significant progress since the introduction of AgPy2MnO4 as oxidant. This oxidant generally gives good conversions and yields, whereas the use of KMnO4 only sometimes works equally well. In order to rationalize this, the reaction mechanism of oxidative alkylamination has been studied. 3-Nitropyridine (1), 1,3-dinitrobenzene (2), and quinazoline (3) were chosen as model substrates and n-butylamine and pyrrolidine as model alkylamines. The rate-limiting step of the mechanism for these substrate/alkylamine combinations was determined. With the use of 1H NMR spectroscopy thermodynamic properties of σ-- adduct formation were deduced and the effect of additives on the adduct formation was investigated. The fundamental insights resulting from these studies led to the identification of a cheap additive (tetrabutylammonium chloride), which in combination with the standard and cheap oxidant KMnO 4 generally gave excellent yields, similar to the ones previously obtained with more expensive AgPy2MnO4.
- Verbeeck, Stefan,Herrebout, Wouter A.,Gulevskaya, Anna V.,Van Der Veken, Benjamin J.,Maes, Bert U. W.
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experimental part
p. 5126 - 5133
(2010/09/18)
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- Synthesis of (alkylamino)nitroarenes by oxidative alkylamination of nitroarenes
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The viability of the oxidative alkylamination process for the derivatization of electron-deficient carboaromatics has been investigated. 1,3-Dinitrobenzene, 1-nitronaphthalene, and 1,5- and 1,8-dinitronaphthalenes have shown to react with a wide range of alkylamines in the presence of an oxidant (KMnO4, AgMnO4, AgPy2MnO4) to give access to the corre sponding N-alkyl-nitroarenamines in moderate to good yields. Nitroarenes are more reactive than azines towards alkylamines.
- Gulevskaya, Anna V.,Verbeeck, Stefan,Burov, Oleg N.,Meyers, Caroline,Korbukova, Inna N.,Herrebout, Wouter,Maes, Bert U. W.
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experimental part
p. 564 - 574
(2009/09/06)
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- Nucleophilic and acid catalyst behavior of a protic ionic liquid in a molecular reaction media. Part 1
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This work presents a new approach using ionic liquids, namely ethylammonium nitrate. The aim was to analyze how the addition of small amounts of a protic ionic liquid to a pure molecular solvent, modifies the microscopic characteristics of a reaction medium. In order to achieve this, a kinetic study of nucleophilic aromatic substitution reactions between 1-fluoro-2, 4-dinitrobenzene and 1-butylamine or piperidine was developed in this type of binary mixtures. We have detected nucleophiles competition originated by the presence of the ionic solvent at very low concentrations, observing the ethylamine derivative as the main substitution product. Moreover, in the light of previous results we have confirmed that the protic ionic liquid can act as both Broensted acid and/or nucleophile. In this connection, we have selected the nucleophilic addition of amines to carbonyl compounds as reaction model. The protic ionic liquid in the presence of aromatic aldehydes substituted by electron-donating groups makes possible the formation of the corresponding imines with good yields. The results demonstrated that the influence of the protic ionic liquid is very important in the course of both reaction systems. Copyright
- Adam, Claudia G.,Fortunato, Graciela G.,Mancini, Pedro M.
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scheme or table
p. 460 - 465
(2010/04/30)
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- Kinetics of snar reactions of 1-phenoxy-nitrobenzenes with aliphatic amines in toluene: Ring substituent and solvent effects on reaction pathways
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Rate constants are reported for the reactions of a series of 4-substituted-1-phenoxy-2,6-dinitrobenzenes 1 and 6-substituted-1-phenoxy-2,4- dinitrobenzenes 2 activated by CF3, COOCH3, CN, NO 2 groups or by ring-nitrogen wi
- Isanbor, Chukwuemeka,Babatunde, Alice Ibitola
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experimental part
p. 1078 - 1085
(2010/07/13)
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- Synthesis and potent antifungal activity against Candida species of some novel 1H-benzimidazoles
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(Chemical Equation Presented) A series of 47 novel N1-alkylated- 2-aryl-5(6)-substituted-1H-benzimidazoles and their three novel indole analogues were synthesized and evaluated for in vitro antifungal activities against Candida species by the tube dilution method. The results showed that compounds 79 and 80, having pyridine at the position C-2, of benzimidazoles exhibited the greatest activity with MIC values of 6.25-3.12 μg/mL. Indole analogues 108-110 have no inhibitory activity.
- Goeker, Hakan,Alp, Mehmet,Ates-Alagoez, Zeynep,Yildiz, Sulhiye
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experimental part
p. 936 - 948
(2009/12/05)
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- A new leaving group in nucleophilic aromatic substitution reactions (S NAr)
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Nucleophilic aromatic substitution of a 2,4-dinitrophenyl substituted pyrazole 1 with primary amines leads to substitution of the pyrazolo substituent. In these nucleophilic aromatic substitution reactions (S NAr), 5-amino-1H-4- pyrazolecarbonitrile (3) acts as a new leaving group.
- Bakavoli, Mehdi,Pordel, Mehdi,Rahimizadeh, Mohammad,Jahandari, Pooneh
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experimental part
p. 432 - 433
(2009/06/30)
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- The effects of ring substituents and leaving groups on the kinetics of SNAr reactions of 1-halogeno- and 1-phenoxy-nitrobenzenes with aliphatic amines in acetonitrile
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Rate constants are reported for the reactions of a series of 1-chloro-, 1-fluoro- and 1-phenoxy-nitrobenzenes activated by CF3 or CN groups or by ring-nitrogen with n-butylamine, pyrrolidine or piperidine in acetonitrile. The results are compar
- Crampton, Michael R.,Emokpae, Thomas A.,Isanbor, Chukwuemeka
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p. 1378 - 1383
(2008/09/18)
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- Effects of ortho- and para-ring activation on the kinetics of S NAr reactions of 1-chloro-2-nitro- and 1-phenoxy-2-nitrobenzenes with aliphatic amines in acetonitrile
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Rate constants are reported for reaction of 4-substituted 1-chloro-2,6-dinitrobenzenes 1, 6-substituted 1-chloro-2,4-dinitrobenzenes 2, and some of the corresponding 1-phenoxy derivatives, 3 and 4, with n-butylamine, pyrrolidine and pi-peridine in acetoni
- Crampton, Michael R.,Emokpae, Thomas A.,Isanbor, Chukwuemeka,Batsanov, Andrei S.,Howard, Judith A. K.,Mondal, Raju
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p. 1222 - 1230
(2007/10/03)
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- Synthesis and magnetic properties of new binuclear Cu(II) complexes with tridentate azomethine ligands
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New binuclear copper complexes of tridentate azomethine ligands with various combinations of N, O, and S donor centers were prepared by various procedures, including template synthesis. The magnetochemical data obtained for the range 2-300 K suggest the occurrence of antiferromagnetic coupling in most of these chelates. The only exception is the complex containing N-tosyl and N-ethyl donor fragments, in which the ferromagnetic exchange is observed. Nauka/Interperiodica 2006.
- Burlov,Ikorskii,Uraev,Koshchienko,Vasil'chenko,Garnovskii,Borodkin,Nikolaevskii,Garnovskii
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p. 1282 - 1287
(2008/02/03)
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- Effect of nucleophile on the kinetics of the reactions of O-(2′,4′-dinitrophenyl)-4-phenyl-3-buten-2-one oxime in acetonitrile
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The kinetics of the reactions of O-(2′,4′ -dinitrophenyl)-4-phenyl-3-buten-2-one oxime have been studied with piperidine, cyclohexylamine, n-butylamine and pyrrolidine in acetonitrile at 35 ± 0.1°. Base catalysis has been observed with piperidine and pyrrolidine. Mechanistic interpretation is given.
- Bhattacharjee, Gurudas,Singh, Ashok K.,Singh, Rupam,Gupta, Anshu
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- Nucleofuge effect: The kinetic and mechanistic studies of the reactions of some O-aryloximes and phenyl naphthyl ether with n-butylamine in acetonitrile
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The aminolysis reactions of O-(2′,4′-dinitrophenyl)-2-naphthol (DNPN), O-(2′,4′-dinitrophenyl)indanoneoxime (DNPIO), and O-(2,4-dinitrophenyl)propanoneoxime (DNPPO) have been carried out with n-butylamine in acetonitrile at 35 ± 0.1°. The coloured product
- Bhattacharjee, Gurudas,Singh, Ashok Kumar,Singh, Rupam,Gairola, Priti
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- Nucleophilic aromatic substitution for heteroatoms: An oxidative electrochemical approach
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The nucleophilic aromatic substitution for heteroatom through electrochemical oxidation of the intermediate σ-complexes (Meisenheimer complexes) in simple nitroaromatic compounds is reported for the first time (NASX process). The studies have been carried out with hydride, cyanide, fluoride, methoxy, and ethanethiolate anions and n-butylamine as a nucleophile, at the cyclic voltammetry (CV) and preparative electrolysis level. The cyclic voltammetry experiments allow for detection and characterization of the σ-complexes and they have led us to a proposal for the mechanism of the oxidation step. Furthermore, the power of the CV technique in the analysis of the reaction mixture throughout the whole chemical and electrochemical process is described.
- Gallardo, Iluminada,Guirado, Gonzalo,Marquet, Jordi
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p. 2548 - 2555
(2007/10/03)
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- Electrochemical synthesis of nitroanilines
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Alkylamines and amides are readily prepared by nucleophilic aromatic substitution of hydrogen in nitroarenes by electrochemical oxidation. Useful yields (15-85%) are achieved in a simple direct and regioselective amination process. The synthetic method has been examined in the absence and presence of external bases, used to promote the first step of the nucleophilic aromatic substitution reaction, i.e. the nucleophilic attack. In both cases, good results were obtained. The unreacted starting material can easily be recovered at the end of the electrochemical oxidation process. This new method represents an environmentally favourable route to amino- and amido-substituted nitroaromatic compounds.
- Gallardo, Iluminada,Guirado, Gonzalo,Marquet, Jordi
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p. 251 - 259
(2007/10/03)
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- Primary alkyl aminolysis of O-(2,4-dinitrophenyl)-p,p'-disubstituted benzophenone oximes in benzene
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The reaction of three O-aryl oximes ((C6H4X)2C=N-O-C6H3(NO2)2; X=Cl-, F-, CH3O-) with three primary amines (n-butylamine, n-hexylamine and n-dodecylamine) have been studied at different temperatures (20-40 deg C) in benzene.The aminolysis reaction have been found to be base-catalysed with an uncatalytic step and second order in amine.The occurrence of uncatalytic route has been explained due to intramolecular hydrogen bonding of ammonium proton to the oxygen of leaving group which finds support in the low energy of activation observed.The reaction rates decrease in the order BuNH2>HexNH2>DodNH2 which has been explained in the light of steric hindrance.
- Jain, A. K.,Singh, P.,Atray, Neeraj,Sahoo, B. B.
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p. 1047 - 1052
(2007/10/03)
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- Catalysis in Nucleophilic Aromatic Substitution Reactions. The Presence of Molecular Complexes on the Pathway of Reactions between 1-Fluoro- and 1-Chloro-2,4-dinitrobenzene and Aliphatic Amines
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The kinetics of reactions between 1-halogeno-2,4-dinitrobenzene (halogen = F, Cl) and butylamine and piperidine were re-investigated in cyclohexane.The kobs values (s-1 mol-1 dm3) increased with increases in the initial concentration of the reacting amine.Investigation of the reaction mixtures at zero reaction time, indicated the presence of an interaction between the substrate and the amine which occurred in a rapidly established equilibrium and which preceded the substitution process.The nature of the molecular complexes observed is discussed.Present and previous data indicate that the kobs increase was difficult to explain with the traditional hypotesis of proton and leaving group departure as a rate determining step.A better rationalisation of the experimental data may be obtained by involving the molecular complexes on the substitution reaction pathway.
- Forlani, Luciano
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p. 1525 - 1530
(2007/10/02)
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- Base-catalysed aromatic nucleophilic substitution reactions of some O-aryl oximes with piperidine and morpholine in benzene
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Aminolysis of O-(2,4-dinitrophenyl) derivatives of benzophenone oxime and 4'-bromobenzophenone oxime with piperidine and morpholine has been studied in benzene at 35 +/- 0.1 deg C.These reactions show inverse temperature effect and third order dependence on amine.The results have been explained on the basis of electrophilic catalysis by homoconjugated acids.It has been concluded from these results that third order dependence on cyclic amines and second order on noncyclic amine is usually noted for aminolysis reactions in benzene.
- Jain, Ajay K,Gupta, V K,Kumar, Anurag,Singh, Pritam
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p. 690 - 692
(2007/10/02)
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- CATALYSIS IN NUCLEOPHILIC AROMATIC SUBSTITUTION REACTIONS. KINETIC BEHAVIOUR OF 2-HYDROXYPYRIDINE AND RELATED COMPOUNDS IN REACTIONS BETWEEN 1-FLUORO-2,4-DINITROBENZENE AND AMINES
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The rate of reactions between 1-fluoro-2,4-dinitrobenzene and aliphatic amines is enhanced by the presence of cyclic (or non-cyclic) amidic systems.This kinetic behaviour is explained by the presence of some equilibria involving the catalyst and both subs
- Forlani, Luciano,Marianucci, Elisabetta,Todesco, Paolo E.
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p. 349 - 353
(2007/10/02)
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- Aromatic Nucleophilic Substitution Reactions of Oxime Ethers with Aliphatic Primary and Secondary Amines in Benzene
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Reactions of various oxime ethers with the primary alkylamines propyl-, butyl-, pentyl-, and hexylamine and with pyrrolidine, a secondary alkyl amine, have been studied in benzene at 35 +/- 0.1 deg C.These reactions have all been found to be wholly base catalysed.Some reactions, especially those involving strong nucleophiles and substrates with poor leaving groups , exhibit a third-order dependence on amine concentration which has been explained on the basis of a cyclic transition-state mechanism.These reactions also show an inverse-temperature effect. Reactions with substrates which have good leaving groups and weaker nucleophiles show a second-order dependence on amine concentration.These reactions show normal temperature effects with low energy of activation.This low energy of activation and high negative entropy of activation support the cyclic transition-state mechanism invoked to explain these data.
- Jain, Ajay K.,Gupta, Vinod K.,Kumar, Anurag
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- Aminolysis of Oxime Ethers in Protic and Aprotic Solvents
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Reactions of oxime ethers with the primary amines, n-propyl-, n-butyl-, n-pentyl-, and n-hexylamine in DMSO, DMF, and MeCN are strongly catalysed by general bases.The observed second-order rate constants (kA) exhibit a curvilinear dependence on amine concentration leaving a positive intercept.The reactions of piperidine in DMSO follow a wholly catalysed pathway.A plot of kA versus is linear and passes through the origin.No base catalysis is observed for the reactions of n-butylamine in methanol and 1:1 (v/v) methanol-acetonitrile.The participation of the hydrogen- bond donor solvent molecule in the intermediate may account for absence of base catalysis in these solvents.
- Jain, Ajay K.,Kumar, Anurag,Sarma, Kula N.
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p. 153 - 158
(2007/10/02)
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- KINETIC STUDIES AND MICELLAR EFFECT ON THE AMINOLYSIS OF CERTAIN O-ARYL OXIMES
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Rate constants for the aminolysis of a few O-aryl oximes with several primary alkyl amines, CH3NH2-------C6H12NH2 in 1:1 water-acetonitrile are reported.Reactions of methylamine with substrates possessing poor nucleofugues are very weakly sensitive to base catalysis while reactions of higher amines are not.Slightly higher rate of long chain amine may be considered as a consequence of hydrophobic interaction.Cationic micelles of cetyltrimethyl ammonium bromide enhance the rate.Magnitude of micellar catalysis increases towards higher amines.
- Jain, Ajay K.,Velu, V. K.,Sarma, K. N.
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p. 2569 - 2574
(2007/10/02)
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- PHOSPHORORGANISCHE VERBINDUNGEN 118. UMPOLUNG UND SELEKTIVITAT BEI 2,4-DINITROPHENYLESTERN VON PHOSPHIN- UND SULFONSAUREN
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Phosphinicacid-4-nitrophenylester (A) are OH-selective.They react with alcohols forming Phosphinicacidesters (B) (P-O-attack).In contrast to this behaviour phosphinicacid-2,4-dinitro-phenylester 1 react with "Umpolung" (O-C-attack) like 2,4-dinitro-fluorobenzene almost exclusively chemoselective with NH-compounds.The non fluorescent 1-(5-dimethylaminonaphthalene)-sulfonicacid-2',4'-dinitrophenylester 4 is also NH-selective.According with NH-compounds O-C-cleavage is observed and 2,4-dinitro-aniline-derivatives are formed.
- Horner, Leopold,Rocker, Michael
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- CATALYSIS BY AMINE SALTS OF SOME AROMATIC NUCLEOPHILIC SUBSTITUTION REACTIONS
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The reaction of 1-chloro-2,4-dinitrobenzene with aniline in acetonitrile is catalysed by R4NY where Y is Cl, Br, I, or toluene-p-sulphonate, but not by 1,4-diazabicyclooctane (DABCO).When the nucleophile is changed to n-butylamine or morpholine, addition of tetraethylammonium chloride has only a small effect; the reactions of all three nucleophiles are not catalysed by tetraethylammonium perchlorate.The reaction of 1-fluoro-2,4-dinitrobenzene with aniline is strongly catalysed by tetraethylammonium chloride, to a lesser extent by the bromide and toluene-p-sulphonate and also by trimethylamine hydrochloride, but not by tetraethylammonium perchlorate.The reactions of morpholine with 1-fluoro-2,4-dinitrobenzene and piperidine with 2,4-dinitrophenyl phenyl ether are not catalysed by amine salts.The results are consistent with the formation and stabilisation of the intermediate formed in aromatic nucleophilic substitution reactions by the anions of the salts, when the nucleophile is aniline
- Hirst, Jack,Onyido, Ikenna
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p. 711 - 716
(2007/10/02)
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- Functional Micellar Catalysis. Part 5. Catalysis of Activated Amide Hydrolysis by Hydroxy and Imidazole Functionalized Surfactant Systems
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The hydrolysis of N-(n-butyl)-2,4-dinitrotrifluoroacetanilide (IX), N-acetylimidazole (Xa), and N-hexanoylimidazole (Xb), in the pH range 7-8.5, is catalysed by micelles and co-micelles (with cetyltrimethylammonium bromide) of functional surfactants containing the hydroxy-group and/or the imidazole ring .The kinetic effects here observed are significantly different from those previously reported for the same micellar reagents in the hydrolysis of p-nitrophenyl alkanoates.Such differences are ascribed to a change in the rate-limiting step of the acylation of the micellar functions, assuming a common nucleophilic mode of action of the functional micelles in the cleavage of activated esters and amides.
- Fornasier, Roberto,Tonellato, Umberto
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p. 899 - 902
(2007/10/02)
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- The Stabilities of Meisenheimer Complexes. Part 22. The Ionisation of 2,4-Dinitroaniline, its N-Alkylated Derivatives, and 2,6-Dinitroaniline in Methanol-Dimethyl Sulphoxide containing Sodium Methoxide
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2,4-Dinitroaniline and its N-alkylated derivatives react with sodium methoxide in methanol-dimethyl sulphoxide to give conjugate base.However, in the case of 2,6-dinitroaniline, base addition at the 3-position competes with proton loss.The effects of N-alkylation on the acidity of 2,4-dinitroaniline are considered and are compared with the effects of similar substitution in 2,4,6-trinitroaniline.
- Crampton, Michael R.,Wilson, Penelope M.
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p. 1854 - 1858
(2007/10/02)
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- Oxidation of Aryldialkylamines with Cerium(IV) Ammonium Nitrate and Thallium(III) Nitrate
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Nine alkylmethylanilines were oxidised with cerium(IV)ammonium nitrate and thallium(III) nitrate in acetic acid, acetonitrile, and methanol.Reaction products were those deriving from demethylation, dealkylation, and aromatic nitration at positions ortho and para to the amino-group.The ratio between demethylation and dealkylation and between them and aromatic nitration is discussed in terms of (i) the oxidising power and electrophilicity of the reagent and (ii) the co-ordinative properties of the solvent.
- Galliani, Guido,Rindone, Bruno
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p. 828 - 832
(2007/10/02)
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