Comparison of the intrinsic reactivities of carbon and oxygen nucleophiles at the 1,3,5-trinitro-substituted aromatic ring

Cox, Jonathan P.L.; Crampton, Michael R.; Wight, Paul

doi:10.1039/p29880000025

Cited by 17 publications

(16 citation statements)

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“…As we can observe, these rate constants are remarkably low compared with those reported for a number of electron-deficient nitro-substituted aromatic and heteroaromatic substrates [25,26]. For example, log k o values of 0.18 and 0.22 have been found for reactions of 1,3,5-trinitrobenzene 5 with nitroalkane anions in methanol at 25…”

Section: Intrinsic Reactivity Of Triflonesmentioning

confidence: 51%

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Substituent effects on the reactions of aromatic triflones with para‐X‐anilines in methanol: Low intrinsic reactivity and transition state imbalances

Guesmi

Boubaker

2011

Int J of Chemical Kinetics

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A kinetic study is reported for S N A r reactions of 2,4,6-tris(trifluoromethanesulfonyl) anisole 1a with a series of para-X-substituted anilines 2a-e in a methanol solution at various temperatures. The substituent effects on free energy ( = G ), enthalpy ( = H ), and entropy ( = S) of activation are examined. Aniline addition to triflone 1a is characterized by a β X = 0.57, α Z = 0.31, and an imbalance of I = α Z -β X = −0.26. The imbalance shows that resonance development lags behind C N bond formation at the transition state. Interestingly, analysis of the results in terms of Marcus theory reveals that these S N Ar are associated with some extremely low intrinsic reactivity (log k o = −1.25).

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Section: Intrinsic Reactivity Of Triflonesmentioning

confidence: 51%

“…• C [26]. Interestingly, the log k o value measured for 1a (log k o = −1.25) in methanol reflects one of the highest intrinsic barriers ever observed for S N Ar reactions.…”

Section: Intrinsic Reactivity Of Triflonesmentioning

confidence: 94%

Substituent effects on the reactions of aromatic triflones with para‐X‐anilines in methanol: Low intrinsic reactivity and transition state imbalances

Guesmi

Boubaker

2011

Int J of Chemical Kinetics

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“…These processes are interpreted in terms of Scheme . It is known that the first step, the equilibration of the phenylnitromethane derivatives with methoxide, is rapid . In view of the 1 H NMR results and the known reactivity with other nucleophiles , the process that we observed was likely the formation of the 5‐adduct.…”

Section: Resultsmentioning

confidence: 59%

“…. The value of 0.03 can be compared with values of k 0 , 0.20 and 0.05 found previously for corresponding reactions of the nitroalkane anions with trinitrobenzene and nitrobenzofurazans, respectively. The values of the intrinsic rate coefficients are thought to reflect the amount of electronic‐structural reorganization and solvent reorganization accompanying a reaction; the more reorganization required, the lower the reactivity.…”

Section: Resultsmentioning

confidence: 74%

“…Previous reports have largely concentrated on determining the structures of the adducts formed, although kinetic data are available for the reactions of nitroalkane anions with TNB in methanol and with DNBF in water. In a previous study, kinetic and equilibrium measurements of the reactions of carbanions derived from nitroalkane and benzyltriflone anions with nitrobenzofurazan derivatives in methanol were also investigated…”

Section: Introductionmentioning

confidence: 99%

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Reactions of Substituted Phenylnitromethane Carbanions with Aromatic Nitro Compounds in Methanol: Carbanion Reactivity, Kinetic, and Equilibrium Studies

Asghar

2014

Int J of Chemical Kinetics

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The feasibility of carrying out nucleophilic addition from electron‐deficient heteroaromatics has been addressed through a detailed investigation of the interaction of a two 7‐substituted‐nitrobenzofurazan (R = OMe 2a; R = Cl 2b) with a series of substituted‐nitroaryl anions (X = 4‐NO2 1a; X = 3‐NO2 1b; X = 4‐CN 1c; X = 4‐Br 1d), all reactions first lead to the quantitative formation of the σ‐adducts 3a–d and 4a–d arising from covalent addition of the nucleophile to the C‐5 carbon. The rate and equilibrium constants for the formation of σ‐adducts 3a–d and 4a–d (k5, K5) together with the rate constants for their decomposition (k−5) have been determined in methanol at 25°C, allowing a determination of intrinsic rate constants, k0 = 0.03, the lower k0 value reflects the very strong salvation by methanol of the negative charge on the nitro group. The discovery of a linear correlation between the E and pKaMeOH parameters allows a calibration of the electrophilicity power of 2a and 2b, E = −11.67 and −10.29, respectively. Applying the general approach to nucleophilicity/electrophilicity recently developed by Mayr et al. through the relationship log k = s(E + N), a successful ranking of our nitroaryl anions 1a–d on the general nucleophilicity scale (N) has been carried out. The N values of 1a–d are found to cover a range from 15.78 to 16.69. The results are compared with previously reported data in water and DMSO.

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Nucleophilic Aromatic Substitution

Crampton

2015

Arene Chemistry

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Comparison of the intrinsic reactivities of carbon and oxygen nucleophiles at the 1,3,5-trinitro-substituted aromatic ring

Cited by 17 publications

References 1 publication

Substituent effects on the reactions of aromatic triflones with para‐X‐anilines in methanol: Low intrinsic reactivity and transition state imbalances

Substituent effects on the reactions of aromatic triflones with para‐X‐anilines in methanol: Low intrinsic reactivity and transition state imbalances

Reactions of Substituted Phenylnitromethane Carbanions with Aromatic Nitro Compounds in Methanol: Carbanion Reactivity, Kinetic, and Equilibrium Studies

Nucleophilic Aromatic Substitution

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