- The mechanism of aromatic nucleophilic substitution reaction between ethanolamine and fluoro-nitrobenzenes: An investigation by kinetic measurements and DFT calculations
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We have studied the kinetics and elucidated the mechanism by DFT calculation of the reaction between ethanolamine (EOA) and 1-fluoro-2,4- dinitrobenzene (DNFB) in acetonitrile and toluene. To determine the contribution of the nitro group, the activation energy of the reaction between ethanolamine and 1-fluoro-2-nitrobenzene (MNFB) vs. DNFB was determined in acetonitrile and calculated by DFT method. Kinetic measurements reveal that the reaction is faster in acetonitrile than in toluene. The reaction follows overall second-order kinetics: first order with respect to both EOA and DNFB which is similar to the results reported for reaction between other primary amines and 1-substituted-2,4-dinitrobenzenes. The calculations by using DFT methods reveal that the mechanism of the reaction involves the formation and decomposition of a Meisenheimer complex (MC). DFT calculations also reveal that the activation energy of the reaction is highest in vacuum and decreases with increasing polarity of the solvent reaching a minimum in acetonitrile. In addition, activation energies obtained by both DFT calculations and experiments show that the reactivity of MNFB is less than that of DNFB showing the effect of the 4-nitro group.
- Jose,Cyriac,Moolayil,Sebastian,George
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- Synthesis of o-Nitroarylamines via Ipso Nucleophilic Substitution of Sulfonic Acids
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A mild, efficient, and eco-friendly method for the synthesis of o-nitroarylamine from o-nitroaryl sulfonic acid via ipso nucleophilic aryl substitution by amine is described. The products have been obtained with good yields at room temperature without the assistance of any metal, activating agent, or toxic oxidant. This method is useful for racemization-free synthesis of N-aryl amino acid esters.
- Manne, Srinivasa Rao,Chandra, Jyoti,Mandal, Bhubaneswar
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supporting information
p. 636 - 639
(2019/01/21)
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- Specific nucleophile-electrophile interactions in nucleophilic aromatic substitutions
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We herein report results obtained from an integrated experimental and theoretical study on aromatic nucleophilic substitution (SNAr) reactions of a series of amines towards 1-fluoro-2,4-dinitrobenzene in water. Specific nucleophile-electrophile interactions in the title reactions have been kinetically evaluated. The whole series undergoes SNAr reactions where the formation of the Meisenheimer complex is rate determining. Theoretical studies concerning specific interactions are discussed in detail. It is found that H-bonding effects along the intrinsic reaction coordinate profile promote the activation of both the electrophile and the nucleophile. Using these results, it is possible to establish a hierarchy of reactivity that is in agreement with the experimental data. Second order energy perturbation energy analysis highlights the strong interaction between the ortho-nitro group and the acidic hydrogen atom of the amine. The present study strongly suggests that any theoretical analysis must be performed at the activated transition state structure, because the static model developed around the reactant states hides most of the relevant specific interactions that characterize the aromatic substitution process.
- Ormazábal-Toledo, Rodrigo,Contreras, Renato,Tapia, Ricardo A.,Campodónico, Paola R.
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supporting information
p. 2302 - 2309
(2013/04/10)
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- Nucleotides. Part LXXVIII: Double labeling of nucleosides and nucleotides
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Several N(-hydroxyalkyl)-2,4-dinitroanilines were transformed into their phosphoramidites (see 5 and 6 in Scheme 1) in view of their use as fluorescence quenchers, and modified 2-aminobenzamides (see 9, 10, 18, and 19 in Scheme 1) were applied in model re
- Maier, Thomas,Pfleiderer, Wolfgang
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experimental part
p. 2365 - 2392
(2011/02/18)
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- Kinetic studies on the reactions of O-(2′,4′-dinitrophenyl) 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one oxime with nucleophiles in aprotic solvents - Mechanism for the uncatalysed pathway
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Kinetics of the reactions of the title compound with some amines as nucleophiles in aprotic solvents have been investigated at the λmax of the aminolysis product at 35 ± 0.1 °C under pseudo-first order conditions. The reaction is overall second order, first with respect to each reactant. The second order rate coefficients decreased with increase in [amine] in all cases. Formation of an electron donor-acceptor complex is indicated. The temperature effect on the reaction rate has been studied in the range (293-318 K). The entropy of activation parameters are large and negative in all cases indicating formation of a crowded transition state. Mechanistic interpretation is given.
- Bhattacharjee,Singh,Gupta, Anshu
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p. 365 - 369
(2008/09/16)
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- Aryl-containing esters of triphosphoric acid as substrates of terminal deoxynucleotidyl transferase
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A new group of terminal deoxynucleotidyltransferase (TDT) substrates, namely, non-nucleoside triphosphates (NNTP) bearing 5-substituted 2,4-dinitrophenyl fragments instead of nucleoside residues was synthesized. Copyright Taylor & Francis Group, LLC.
- Khandazhinskaya,Matyugina,Alexandrova,Shirokova,Kukhanova,Jasko
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p. 641 - 644
(2008/03/18)
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- Effect of substituent on regioselectivity and reaction mechanism in aminolysis of 2,4-dinitrophenyl X-substituted benzenesulfonates
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(Chemical Equation Presented) We report on a kinetic study for the nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzensulfonates (X = 4-MeO, 1a, and X = 4-NO2, 1c) with a series of primary amines in 80 mol % H2O/20 mol % DMSO at 25.0 °C. The reactions proceed through S-O and C-O bond fission pathways competitively. The fraction of the S-O bond fission increases as the attaching amine becomes more basic and the substituent X changes from 4-MeO to 4-NO2, indicating that the regioselectivity is governed by the electronic nature of the substituent X as well as the basicity of amines. The S-O bond fission has been suggested to proceed through an addition intermediate with a change in the rate-determining step (RDS) at pK°a = 8.9 ± 0.1. The electronic nature of the substituent X influences kNS-O and k1 values, but not the k2/k-1 ratios and the pK°a value significantly. Stabilization of the ground state (GS) through resonance interaction between the electron-donating substituent and the electrophilic center has been suggested to be responsible for the decreased reactivity of 1a compared to 1c. The second-order rate constants for the C-O bond fission exhibit no correlation with the electronic nature of the substituent X. The distance effect and the nature of the reaction mechanism have been suggested to be responsible for the absence of the correlation.
- Um, Ik-Hwan,Hong, Jin-Young,Seok, Jin-Ah
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p. 1438 - 1444
(2007/10/03)
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- Kinetics of reactions of o-(2,4-dinitrophenyl)indanone oxime with cyclohexylamine, piperidine and ethanolamine in acetonitrile
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Effect of nucleophile on the reactions of o-(2,4-dinitrophenyl) indanone oxime (DNPIO) has been studied with cyclohexylamine (CHA), ethanolamine (ETA) and piperidine (PIP) in acetonitrile at 35±0.1°C. Reactions of DNPIO with CHA and ETA are kinetically of second order. However, the reactions with PIP are wholly base catalyzed and a third order dependence on PIP has been observed.
- Bhattacharjee, Gurudas,Singh, Ashok Kumar,Singh, Rupam,Gairola, Priti
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p. 1051 - 1055
(2007/10/03)
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- Unusual reaction of 1,4-diamino-2-nitrobenzene derivatives toward nucleophiles: Catalysis by sodium sulphite
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Unusual substitution of amino group occurs by reactions of some 1,4diamino-2-nitrobenzenes (semipermanent hair dyes) and nucleophiles (NH3, H2O). The reaction is catalyzed by sodium sulfite. The obtained products are suspected of being toxic substances which may be present in cosmetic matrices. Apparently, this reaction is a nucleophilic aromatic substitution but it may be explained by a mechanism involving a tautomeric form of substrate.
- Forlani, Luciano,Boga, Carla,Mazza, Milena,Cavrini, Vanni,Andrisano, Vincenza
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p. 4647 - 4654
(2007/10/03)
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- SN2 Displacement on 2-(Alkylthio)ethyl Derivatives
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We have studied the reaction mechanism of various 2-(alkylthio)ethyl and 2-(arylthio)ethyl derivatives with strong nucleophiles in an attempt to overcome powerful neighboring sulfur participation and shift reaction to a direct displacement SN2 mechanism.The 2,4-dinitrophenolate derivative of specifically deuteriated 2-(methylthio)ethanol reacts by an aromatic substitution mechanism (SNAr) when exposed to amines in aprotoc solvents.Use of sulfonate esters avoids competition from the SNAr mechanism.The rate of reaction of these esters in dimethyl sulfoxide (DMSO) or acetonitrile is independent of concentration of added methylamine, thiourea, urea, or iodide, thus indicating continued SN1 reaction with neighboring sulfur participation.Asd would be expected on this basis, but in contrast to previous mechanistic suggestions, the product for reaction with iodide in acetone shows complete scrambling of methylene groups.In contrast, reaction with thiophenolate ions in DMSO proceeds by direct nucleophilic displacement (an SN2 mechanism), as shown by second-order kinetics and unrearranged product.This is the first demonstration of SN2 displacement on a 2-(alkylthio)ethyl or 2-(arylthio)ethyl derivative.
- Herati-Sedaghat, M. R.,McManus, Samuel P.,Harris, J. Milton
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p. 2539 - 2543
(2007/10/02)
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- NEW CARDENOLIDE GLYCOSIDES FROM THE DEFENCE GLANDS OF CHRYSOLININA BEETLES (COLEOPTERA : CHRYSOMELIDAE)
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The composition of the defence secretions of six species of chrysomelid beetles (Chrysolina polita, C. americana, C. grossa, C. herbacea, C. fastuosa, and Oreina gloriosa) belonging to the sub-tribe Chrysolinina has been investigated.Two known cardenolide
- Oycke, S. Van,Randoux, T.,Braekman, J. C.,Daloze, D.,Pasteels, J. M.
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p. 297 - 312
(2007/10/02)
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- Chemotherapeutically active nitro compounds. I. Nitroanilines
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More than 200 nitro compounds, most of them nitroaniline derivatives substituted with one or more radicals having a basic reaction, were prepared and investigated as to their therapeutic activity against bacteria, fungi, protozoa, helminths, viruses and tumors. Several mono nitrobenzenes with a radical having a basic reaction showed a weak in vitro activity against gram positive bacteria and against Crocker's sarcoma 180; they also showed systemic activity against nematodes (Aspiculuris tetraptera) and viruses. The majority of therapeutically active compounds with pronounced in vitro activity against Trichomonas fetus, Entamoeba histolytica, Schistosoma mansoni, cestodes, nematodes (Ancylostoma caninum), viruses (influenza, MHV, SAV and EMC) and various types of carcinoma (Ehrlich's carcinoma, leukemia 1210, Crocker's sarcoma 180) were dinitrobenzene derivatives with one radical having a basic reaction and electropositive groups or unreactive or reactive chlorine atom, and di nitrobenzene with two equal or two different radicals having a basic reaction. Compound No. 70 revealed a marked in vitro activity against fungi (Trichophyton; Microsporum, Candida albicans). Other nitro compounds such as bis mono and bis dinitrobenzene derivatives likewise showed a systemic action against E. histolytica, viruses and, in particular, carcinoma (Crocker's sarcoma 180, Ridgway's osteosarcoma). Oxygen and sulfur analogue compounds as well as compounds produced by reduction also possessed a distinct activity against E. histolytica and viruses. On the basis of the present results, the dinitrobenzenes substituted with two radicals having a basic reaction include a number which have in common a recognizable structure/activity relationship in respect to E. histolytica, Schistosoma mansoni and different types of viruses. The activity against viruses in this class of compounds is probably due to an increased interferon production in the host animal. Whether the mechanism of action is the same against E. histolytica or Schistosoma mansoni has not been determined so far. A tumorigenic effect was observed mainly in those di nitrobenzenes which are classed as alkylating compounds. Because of the small chemotherapeutic index, the trials were not continued with the most effective compounds mentioned.
- Winkelmann,Raether,Dittmar,et al.
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p. 681 - 708
(2007/10/05)
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