1
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Campodónico PR, Alarcón-Espósito J, Olivares B. Kinetics and Reaction Mechanism of Biothiols Involved in S NAr Reactions: An Experimental Study. Front Chem 2022; 10:854918. [PMID: 35755252 PMCID: PMC9213796 DOI: 10.3389/fchem.2022.854918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/25/2022] [Indexed: 11/13/2022] Open
Abstract
Few kinetic parameters, or reaction rates, are known up to date in detail about 1-chloro and 1-fluoro-2,4-dinitrobenzene (ClDNB and FDNB, respectively) with a series of biothiols in aqueous media. These biological nucleophiles with thiol groups have been widely used as a reference in nucleophile reactivity assays due to their prevalence and cellular abundance. The main aim of this study was to elucidate the reaction mechanism based on Brönsted-type plots and reactivity patterns of the electrophile/nucleophile pairs. A complete kinetic study was performed in terms of the comparison of Brönsted-type slope parameters (βnuc) for the reactions and was used for assigning the mechanism and the rate-determining step associated with the reaction route. A mass spectrometry analysis demonstrated that the nucleophilic center of the biothiols is the -SH group and there is only one kinetic product. The kinetic study suggests that the reaction mechanism might be the borderline between concerted and stepwise pathways. An amine–enol equilibrium for the most reactive nucleophiles appears to be the main determining factor controlling the nucleophilic attack in the nucleophilic aromatic substitution reactions investigated, highlighting the anionic form for these nucleophiles. This amine–enol equilibrium involves a hydrogen bond which stabilizes the intermediate species in the reaction pathway. Thus, intramolecular bonds are formed and enhance the nucleophilic strength through the contribution of the solvent surrounding the electrophile/nucleophile pairs. Finally, we highlight the importance of the formation of electrophile/nucleophile adducts that could modify structures and/or functions of biological systems with potential toxic effects. Therefore, it is essential to know all these kinetic and reactivity patterns and their incidence on other studies.
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Affiliation(s)
- Paola R Campodónico
- Centro de Química Médica, Instituto de Ciencias e Innovación en Medicina, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Jazmín Alarcón-Espósito
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Belén Olivares
- Centro de Química Médica, Instituto de Ciencias e Innovación en Medicina, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
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2
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Um IH, Jung YJ, Dust JM. Kinetic Study on Pyridinolysis of Aryl Benzenesulfonates: Factors Governing Regioselectivity and Reaction Mechanism. CAN J CHEM 2022. [DOI: 10.1139/cjc-2021-0287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A kinetic study is reported for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates (1a-1f) and Y-substituted-phenyl benzenesulfonates (2a-2f) with Z-substituted-pyridines. The reactions proceed through S‒O and C‒O bond scissions competitively. The Yukawa-Tsuno plot for the reactions of 1a-1f with 4-oxypyridine (S‒O bond fission) exhibits an excellent linearity. The Brønsted-type plot for the reactions of 2,4-dinitrophenyl benzenesulfonate (1d) with pyridines (S‒O bond fission) is also linear with βnuc = 0.62. The Brønsted-type plot for the reactions of 2a-2f with 4-oxypyridines (S‒O bond fission) is linear with βlg= ‒1.17. Thus, the reactions have been concluded to proceed through a concerted mechanism, in which leaving-group expulsion is significantly more advanced than bond formation between the electrophilic center and nucleophile at the transition state. The Hammett plot for the reactions of 1a-1f with 4-oxypyridine (C‒O bond fission) exhibits scattered points with ρX= 0.98. The Brønsted-type plot for the reactions of 1d with Z-substituted-pyridines (C‒O bond fission) results in an excellent linear correlation with βnuc = 0.38. Thus, the reactions (C‒O bond fission) have been concluded to proceed through a stepwise mechanism with a Meisenheimer complex, in which expulsion of the leaving group occurs after the rate-determining step. Factors governing regioselectivity and reaction mechanism are discussed.
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Affiliation(s)
- Ik-Hwan Um
- Ewha Womans University, Department of Chemistry, Division of Nano Sciences, Ewha Womans University, Seoul 120 � 750, Korea, Seoul, Korea (the Republic of), 120-750, ,
| | - Yoon Jae Jung
- Pohang University of Science and Technology, 34995, Pohang, Korea (the Republic of)
| | - Julian Michael Dust
- Memorial University of Newfoundland, 7512, Departments of Chemistry and Environmental Science, St. John's, Newfoundland and Labrador, Canada, A1C 5S7
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3
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Ashworth IW, Frodsham L, Moore P, Ronson TO. Evidence of Rate Limiting Proton Transfer in an S NAr Aminolysis in Acetonitrile under Synthetically Relevant Conditions. J Org Chem 2021; 87:2111-2119. [PMID: 34694113 DOI: 10.1021/acs.joc.1c01768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An early synthetic step in the synthesis of adavosertib, AZD1775, is the SNAr reaction between 4-fluoronitrobenzene and 1-methylpiperazine in acetonitrile. A simple kinetics-based design of four reaction profiling experiments was used to investigate the kinetics of the reaction for the purpose of building a kinetic model. Fitting of the reaction profile data from two experiments conducted at 70 °C with a different excess of 1-methylpiperazine showed the reaction to follow a third-order rate law with a second-order dependence upon 1-methylpiperazine. This was rationalized in terms of the reaction following a rate-limiting proton transfer mechanism (base catalyzed) in which the progress to product is driven by a proton transfer involving a second molecule of 1-methylpiperazine. The experimentally determined entropy of activation of -180 J K-1 is consistent with this mechanism. The formation of a low level impurity was found to be due to the presence of traces of piperazine in the 1-methylpiperazine, which was shown to react approximately 15 times faster than 1-methylpiperazine at 70 °C. The rate constants for the 1-methylpiperazine catalyzed reaction of piperazine, 1-methylpiperazine, and the piperazine derived impurity were found to correlate in a Brønsted type analysis with the pKa's (acetonitrile) of the amine nucleophile.
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Affiliation(s)
- Ian W Ashworth
- Chemical Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield, SK10 2NA, U.K
| | - Lianne Frodsham
- Chemical Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield, SK10 2NA, U.K
| | - Peter Moore
- Early Chemical Development, Pharmaceutical Sciences, R&D BioPharmaceuticals, AstraZeneca, Macclesfield, SK10 2NA, U.K
| | - Thomas O Ronson
- Chemical Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield, SK10 2NA, U.K
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4
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Orlandi M, Escudero-Casao M, Licini G. Nucleophilicity Prediction via Multivariate Linear Regression Analysis. J Org Chem 2021; 86:3555-3564. [PMID: 33534569 PMCID: PMC7901016 DOI: 10.1021/acs.joc.0c02952] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
The concept of nucleophilicity is
at the basis of most transformations
in chemistry. Understanding and predicting the relative reactivity
of different nucleophiles is therefore of paramount importance. Mayr’s
nucleophilicity scale likely represents the most complete collection
of reactivity data, which currently includes over 1200 nucleophiles.
Several attempts have been made to theoretically predict Mayr’s
nucleophilicity parameters N based on calculation
of molecular properties, but a general model accounting for different
classes of nucleophiles could not be obtained so far. We herein show
that multivariate linear regression analysis is a suitable tool for
obtaining a simple model predicting N for virtually
any class of nucleophiles in different solvents for a set of 341 data
points. The key descriptors of the model were found to account for
the proton affinity, solvation energies, and sterics.
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Affiliation(s)
- Manuel Orlandi
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.,CIRCC-Consorzio Interuniversitario per le Reattività Chimiche e la Catalisi, Padova Unit, via Marzolo 1, 35131 Padova, Italy
| | - Margarita Escudero-Casao
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.,CIRCC-Consorzio Interuniversitario per le Reattività Chimiche e la Catalisi, Padova Unit, via Marzolo 1, 35131 Padova, Italy
| | - Giulia Licini
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.,CIRCC-Consorzio Interuniversitario per le Reattività Chimiche e la Catalisi, Padova Unit, via Marzolo 1, 35131 Padova, Italy
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5
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Campodónico PR, Olivares B, Tapia RA. Experimental Analyses Emphasize the Stability of the Meisenheimer Complex in a S NAr Reaction Toward Trends in Reaction Pathways. Front Chem 2020; 8:583. [PMID: 32754575 PMCID: PMC7366874 DOI: 10.3389/fchem.2020.00583] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 06/05/2020] [Indexed: 11/13/2022] Open
Abstract
The mechanism of SNAr reactions between 2-chloro-5-nitropyrimidine with primary and secondary alicyclic amines, respectively, have been studied by kinetic measurements. The kinetic data obtained in aqueous media opens a controversial discussion based on Brönsted-type plots analysis. The first approach based on the kinetic data reveals a non-catalyzed pathway. Then, the subtlety of the mathematical treatment of the kinetic data is discussed over a concerted or stepwise mechanism, respectively.
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Affiliation(s)
- Paola R Campodónico
- Centro de Química Médica, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Belén Olivares
- Centro de Química Médica, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Ricardo A Tapia
- Facultad de Química y Farmacia, Pontificia Universidad Católica de Chile, Santiago, Chile
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6
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Sindi S, El Guesmi N, Asghar BH, Hussein EM. Structure-reactivity relationships on Michael additions of secondary cyclic amines with 3-cyanomethylidene-2-oxindoline derivatives. ARAB J CHEM 2020. [DOI: 10.1016/j.arabjc.2020.03.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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7
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Kim KR, Kim HJ, Hong JI. Electrogenerated Chemiluminescent Chemodosimeter Based on a Cyclometalated Iridium(III) Complex for Sensitive Detection of Thiophenol. Anal Chem 2018; 91:1353-1359. [DOI: 10.1021/acs.analchem.8b03445] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Kyoung-Rok Kim
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Hoon Jun Kim
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Jong-In Hong
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
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8
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Um IH, Song JH, Bae AR, Dust JM. Unexpected medium effect on the mechanism for aminolysis of aryl phenyl carbonates in acetonitrile and H2O: transition-state structure in the catalytic pathway. CAN J CHEM 2018. [DOI: 10.1139/cjc-2018-0204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Upward curvature in the kinetic plots of pseudo first-order rate constants (kobsd) vs. [amine] for the aminolysis of aryl phenyl carbonates (5a–5j) in MeCN demonstrates that these reactions proceed via a zwitterionic tetrahedral intermediate (T±) that partitions between catalyzed and uncatalyzed routes to give the products. Yukawa–Tsuno plots for the reactions of 5a–5j with piperidine result in excellent linear correlations with ρY = 4.82 and r = 0.47 for the uncatalyzed reaction versus ρY = 2.21 and r = 0.21 for the catalyzed reaction. Brønsted plots for reactions of 4-(ethoxycarbonyl)-phenyl phenyl carbonate (5f) with a series of cyclic secondary amines exhibit excellent linear correlations with βnuc = 0.87 and 0.58 for the uncatalyzed and catalyzed reactions, respectively. The ΔH‡ and ΔS‡ values are 0.92 kcal/mol and –50.1 cal/mol K, respectively, for the catalyzed reaction of 5f with piperidine. Deuterium kinetic isotope effects found for reactions of 5f with piperidine/deuterated piperidine are 0.84 (uncatalyzed) and 1.42 (catalyzed). Multi-parameter analysis supports a concerted catalytic pathway involving a six-membered cyclic transition state rather than a traditionally accepted stepwise pathway with an anionic intermediate. The current unexpected results, where T± is the essential central intermediate in this aminolysis, contrast with previous calculation studies that deemed T± unstable in gas phase or MeCN.
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Affiliation(s)
- Ik-Hwan Um
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Ji-Hyun Song
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Ae-Ri Bae
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Julian M. Dust
- Departments of Chemistry and Environmental Science, Grenfell Campus – Memorial University of Newfoundland, Corner Brook, NL A2H 5G4, Canada
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9
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Um IH, Kim MY, Dust JM. Medium effect (water versus MeCN) on reactivity and reaction pathways for the SNAr reaction of 1-aryloxy-2,4-dinitrobenzenes with cyclic secondary amines. CAN J CHEM 2017. [DOI: 10.1139/cjc-2017-0454] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A kinetic study on SNAr reactions of 1-aryloxy-2,4-dinitrobenzenes (1a–1h) with a series of cyclic secondary amines in 80 mol% water – 20 mol% DMSO at 25.0 ± 0.1 °C is reported. The plots of kobsd versus amine concentration curve upward except for the reactions of substrates possessing a strong electron-withdrawing group in the leaving aryloxide with strongly basic piperidine. The curved plots indicate that the reactions proceed through both uncatalytic and catalytic routes. Linear Brønsted-type plots have been obtained for the uncatalyzed and catalyzed reactions of 1-(4-nitrophenoxy)-2,4-dinitrobenzene (1a) with βnuc = 0.84 and 0.78, respectively. The Yukawa–Tsuno plot for the uncatalyzed reactions of 1a–1h with piperidine results in an excellent linear correlation with ρ = 1.66 and r = 0.31. In contrast, rate constants for catalyzed reactions are independent of the electronic nature of the substituent in the leaving group. The current SNAr reactions have been proposed to proceed via a zwitterionic intermediate (MC±) that partitions to products through uncatalytic and catalytic routes. The catalyzed reaction from MC± has been concluded to proceed through a concerted mechanism with a six-membered cyclic transition state (TScycl) rather than via a stepwise pathway with a discrete anionic intermediate (MC−), the traditionally accepted mechanism. Medium effects on the reactivity and reaction mechanism are discussed. Particularly, hydrogen bonding of the amines to water precludes formation of kinetically significant dimers found in some aprotic solvents; no explicit role for water in the catalytic transition state is required or proposed. The specific stabilization of the leaving aryloxides substituted with strong electron-withdrawing groups accounts for the lack of the catalytic pathway in these systems (1a–1c) with piperidine nucleophile.
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Affiliation(s)
- Ik-Hwan Um
- Department of Chemistry, Ewha Womans University, Seoul 120-750, Korea
| | - Min-Young Kim
- Department of Chemistry, Ewha Womans University, Seoul 120-750, Korea
| | - Julian M. Dust
- Departments of Chemistry and Environmental Science, Grenfell Campus, Memorial University of Newfoundland, Corner Brook, NL A2H 5G4, Canada
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10
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Um IH, Kang JS, Dust JM. Alkali metal ion catalysis and inhibition in alkaline ethanolysis of O-Y-substituted-phenyl O-phenyl thionocarbonates: contrasting M + ion effects upon changing electrophilic centre from C=O to C=S. CAN J CHEM 2017. [DOI: 10.1139/cjc-2016-0378] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pseudo-first-order rate constants (kobsd) were measured for nucleophilic substitution reactions of O-Y-substituted-phenyl O-phenyl thionocarbonates (4a–4h) with alkali metal ethoxides (EtOM, M = Li, Na, or K) in anhydrous ethanol at 25.0 ± 0.1 °C. Plots of kobsd vs. [EtOM] exhibited upward curvature for the reaction of O-4-nitrophenyl O-phenyl thionocarbonate (4a) with EtOK in the presence of 18-crown-6-ether (18C6), but showed downward curvature for the reaction with EtOLi, indicating that the reaction is catalyzed by the 18C6-crowned K+ ion, but is inhibited by Li+ ion. The kobsd values were dissected into kEtO− and kEtOM, the second-order rate constant for the reaction with dissociated EtO− and ion-paired EtOM, respectively. The reactivity of EtOM toward 4a increases in the order EtOLi < EtONa < EtO− < EtOK < EtOK/18C6, which is in contrast to that reported previously for the corresponding reaction of 4-nitrophenyl phenyl carbonate (a C=O analogue of 4a), e.g., EtO− ≈ EtOK/18C6 < EtOLi < EtONa < EtOK. The reaction mechanism, including the transition-state model and the origin of the contrasting reactivity patterns found for the reactions of the C=O and C=S compounds, are discussed.
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Affiliation(s)
- Ik-Hwan Um
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Ji-Sun Kang
- Engineering Plastic R&T, Solvay, Seoul 153-023, Korea
| | - Julian M. Dust
- Department of Chemistry and Environmental Science, Grenfell Campus-Memorial University of Newfoundland, Corner Brook, NL A2H 5G4, Canada
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11
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Shin YH, Kang JS, Um IH. Alkaline Hydrolysis of 4-Nitrophenyl X-Substituted-Benzoates Revisited: New Insights from Yukawa-Tsuno Equation. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.11000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Young-Hee Shin
- Department of Chemistry; Seoul National University; Seoul 08826 Korea
| | - Ji-Sun Kang
- Engineering Plastic R&T Solvey; Seoul 153-023 Korea
| | - Ik-Hwan Um
- Department of Chemistry; Ewha Womans University; Seoul 120-750 Korea
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12
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Santos JG, Aliaga ME, Alarcón K, Torres A, Céspedes D, Pavez P. Reactivity and selectivity of the reaction of O,O-diethyl 2,4-dinitrophenyl phosphate and thionophosphate with thiols of low molecular weight. Org Biomol Chem 2016; 14:6479-86. [DOI: 10.1039/c6ob00918b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A kinetics control product by sulfhydryl attack of thiols was observed in the reactions of both triesters with Cys and Hcys, followed by an intramolecular amine attack leading to a thermodynamic control product.
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Affiliation(s)
- J. G. Santos
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Casilla 306
- Santiago 6094411
- Chile
| | - M. E. Aliaga
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Casilla 306
- Santiago 6094411
- Chile
| | - K. Alarcón
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Casilla 306
- Santiago 6094411
- Chile
| | - A. Torres
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Casilla 306
- Santiago 6094411
- Chile
| | - D. Céspedes
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Casilla 306
- Santiago 6094411
- Chile
| | - P. Pavez
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Casilla 306
- Santiago 6094411
- Chile
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13
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Um IH, Kim MY, Cho HJ, Dust JM, Buncel E. The α-effect in the SNAr reaction of 1-(4-nitrophenoxy)-2,4-dinitrobenzene with anionic nucleophiles: effects of solvation and polarizability on the α-effect. CAN J CHEM 2015. [DOI: 10.1139/cjc-2015-0073] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A kinetic study on SNAr reactions of 1-(4-nitrophenoxy)-2,4-dinitrobenzene (1a) with various anionic nucleophiles in 80 mol% water – 20 mol% DMSO at 25.0 °C is reported. The Brønsted-type plot for the reaction of 1a with a series of substituted phenoxides and HOO− results in an excellent linear correlation with βnuc = 1.17. However, OH− exhibits dramatic negative deviation from the Brønsted-type plot, while N3−, C6H5S−, and butane-2,3-dione monoximate (Ox−) deviate positively from linearity. HOO− is 680-fold more reactive than OH− but does not exhibit the α-effect. In contrast, Ox− is 166-fold more reactive than isobasic 4-Cl−C6H4O− and exhibits the α-effect. Differential solvation effects have been suggested to be responsible for the α-effect in this study, i.e., Ox− exhibits the α-effect, since it is 5.7 kcal/mol less strongly solvated than 4-Cl−C6H4O− in the reaction medium, while HOO− does not show the α-effect due to a strong requirement for partial desolvation before nucleophilic attack. The highly enhanced reactivity of polarizable N3− and C6H5S− and extremely decreased reactivity of nonpolarizable OH− are in accord with the hard–soft acid and base principle.
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Affiliation(s)
- Ik-Hwan Um
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Min-Young Kim
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Hyo-Jin Cho
- Department of Chemistry, Duksung Women’s University, Seoul 132-714, Korea
| | - Julian M. Dust
- Departments of Chemistry and Environmental Science, Grenfell Campus, Memorial University of Newfoundland, Corner Brook, NL A2H 5G4, Canada
| | - Erwin Buncel
- Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
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14
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Yang K, Kim MY, Um IH. S NAr Reactions of 1-Halo-2,4-dinitrobenzenes with Alkali-Metal Ethoxides: Differential Stabilization of Ground State and Transition State Determines Alkali-Metal Ion Catalysis or Inhibition. B KOREAN CHEM SOC 2015. [DOI: 10.1002/bkcs.10344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Kiyull Yang
- Department of Chemistry Education; Gyeongsang National University; Jinju 660-701 Korea
| | - Min-Young Kim
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
| | - Ik-Hwan Um
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
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15
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Seo HO, Kim MY, Han SY, Um IH. Kinetic Study on S NAr Reactions of 1-(Y-Substituted-phenoxy)-2,4-dinitrobenzenes with Azide Ion: Effect of Changing Nucleophile from Hydroxide to Azide Ion on Reaction Mechanism and Reactivity. B KOREAN CHEM SOC 2015. [DOI: 10.1002/bkcs.10333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Hyeon-Ok Seo
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
| | - Min-Young Kim
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
| | - So-Yeop Han
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
| | - Ik-Hwan Um
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
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16
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Moon JH, Kim MY, Han SY, Um IH. Nucleophilic Substitution Reactions of 2,4-Dinitrophenyl X-Substituted-Benzenesulfonates and Y-Substituted-Phenyl 4-Nitrobenzenesulfonates with Azide Ion: Regioselectivity and Reaction Mechanism. B KOREAN CHEM SOC 2015. [DOI: 10.1002/bkcs.10259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Ji-Hyun Moon
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
| | - Min-Young Kim
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
| | - So-Yeop Han
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
| | - Ik-Hwan Um
- Department of Chemistry and Nano Science; Ewha Womans University; Seoul 120-750 Korea
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17
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Um IH, Kim MY, Bae AR, Dust JM, Buncel E. Evidence for a Catalytic Six-Membered Cyclic Transition State in Aminolysis of 4-Nitrophenyl 3,5-Dinitrobenzoate in Acetonitrile: Comparative Brønsted-Type Plot, Entropy of Activation, and Deuterium Kinetic Isotope Effects. J Org Chem 2014; 80:217-22. [PMID: 25438168 DOI: 10.1021/jo502303f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ik-Hwan Um
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Min-Young Kim
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Ae-Ri Bae
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Julian M. Dust
- Departments
of Chemistry and Environmental Science, Grenfell Campus, Memorial University of Newfoundland, Corner Brook, Newfoundland
and Labrador A2H 5G4, Canada
| | - Erwin Buncel
- Department
of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6, Canada
| |
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