Kinetics and mechanism of the pyridinolysis of aryl dithiobenzoates in acetonitrile

Oh, Hyuck Keun; Lee, Jae Myon; Lee, Hai Whang; Lee, Ikchoon

doi:10.1002/kin.20000

Cited by 34 publications

(12 citation statements)

References 35 publications

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“…Such kinds of studies using physical properties such as melting points and dipole moments of benzoic acids were even reported from our laboratory . But to the authors' knowledge, the present article presents the first of its kind to observe a nonlinear Taft correlation, though there are several reports on nonlinear Hammett correlations in the literature .…”

Section: Introductionmentioning

confidence: 64%

Nonlinear Taft Polar Free Energy Relationship: Reactions of N‐Substituted Benzyl Amines with Benzyl Bromide in Methanol

Ravi

Sanjeev

Jagannadham

2013

Int J of Chemical Kinetics

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The rates of reactions of N‐substituted benzyl amines with benzyl bromide were measured using a conductivity technique in methanol medium. The reaction followed a total second‐order path. The end product of the reaction is identified as dibenzyl alkyl amine (C6H5CH2N(R)CH2C6H5). The rates increased with a decrease in the electron‐donating capacity or with an increase in the Taft σ* value of electron‐donating alkyl substituents (R) such as t‐butyl (σ* = −0.3), i‐propyl (σ* = −0.19), n‐butyl (σ* = −0.13), and ethyl (σ* = −0.1) on nitrogen of the amine until the Taft σ* value becomes zero for the methyl group (σ CH 3* = 0.00), and then the rates decreased with an increase in the electron‐withdrawing capacity or with an increase in the Taft σ* value of electron‐withdrawing substituents (R) such H and C6H5 (σnormalH* = 0.49 and σC60.16emH5*= 0.6). The locus of the Taft polar free energy relationship has a maximum near the point for N‐methyl benzyl amine, showing that there is a sharp change in the rate‐determining step. A mechanism involving formation of an SN2‐type transition state between the amine nucleophiles and the benzyl bromide and its subsequent decomposition is proposed. Activation parameters were calculated and are discussed.

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Section: Introductionmentioning

confidence: 64%

Nonlinear Taft Polar Free Energy Relationship: Reactions of N‐Substituted Benzyl Amines with Benzyl Bromide in Methanol

Ravi

Sanjeev

Jagannadham

2013

Int J of Chemical Kinetics

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“…A careful examination of the literature showed that Brønsted plots highlighting two straight lines with two different slopes are rarely reported in S N Ar reactions. However, nonlinear Brønsted‐type plots have been reported for many nucleophilic substitution reactions 12–18. Koh and coworkers, for example, have observed a curved Brönsted‐type plot with β nuc decreasing from 0.71 ± 0.03 to 0.21 ± 0.06 as the pyridine basicity increases for the reaction of methyl chloroformate with X‐pyridines in acetonitrile, at 25°C [13b].…”

Section: Resultsmentioning

confidence: 99%

Nonlinear Brønsted and Hammett Correlations Associated with Reactions of 4‐Chloro‐7‐nitrobenzofurazan with Anilines in Dimethyl Sulfoxide Solution

Jmaoui

Boubaker

Goumont

2013

Int J of Chemical Kinetics

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The kinetics and mechanism of nucleophilic aromatic substitution reactions of 4-chloro-7-nitrobenzofurazan 1 with 4-X-substituted anilines 2a-g (X = OH, OCH 3 , CH 3 , H, I, Cl, and CN) are investigated in a dimethyl sulfoxide (Me 2 SO) solution at 25 • C. The Hammett plot of log k 1 versus σ is nonlinear for all the anilines studied due to positive deviations of the electron-donating substituents. However, the corresponding Yukawa-Tsuno plot resulted in a good linear correlation with σ + r (σ + − σ ). The corresponding Brønsted-type plot is also nonlinear, i.e., the slope (β nuc ) changes from 1.60 to 0.56 as the basicity of anilines decreases. These results indicate a change in a mechanism from a polar S N Ar process for less basic nucleophiles (X = I, Cl, and CN) to a single electron transfer for more basic nucleophiles (X = OH, OCH 3 , and CH 3 ). The satisfactory log k 1 versus E o correlation obtained for the reactions of 1 with anilines 2a-d in the present system is consistent with the proposed mechanism. Interestingly, the β nuc = 1.60 value measured for 1 in Me 2 SO reflects one of the highest coefficients Brønsted ever observed for S N Ar reactions.

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“…Oh et al [39] investigated the aminolysis of aryl dithiobenzoates with substituted X-pyridines in acetonitrile at 60 °C. A curved Brønsted plot was obtained with a change in slope from a large value (β x = 0.7 -0.8) to a small value (β x = 0.2) at pK a = 5.20.…”

Section: Effect Of Aniline Basicity and Mechanismmentioning

confidence: 99%

Single electron transfer in S_NAr process: Reactions of 2,4,6-tris(trifluoromethanesulfonyl)anisole with anilines in dimethyl sulfoxide

Guesmi

Boubaker

Goumont

2013

Progress in Reaction Kinetics and Mechanism

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Second-order rate constants (k 1 ) have been measured spectrophotometrically for reactions of 2,4,6-tris(trifluoromethanesulfonyl)anisole 1 with 4-X-substituted anilines (X = OH, OCH 3 , CH 3 , H, I and Cl) 2a -f in dimethyl sulfoxide (DMSO) at 25 °C. The Hammett plot is nonlinear, i.e. the anilines having an electron-donating substituent exhibit positive deviations from the log k 1 versus correlation. The Hammett plot consists of two intersecting straight lines, i.e. ρ = -1.40 for electron-withdrawing substituents (X = I and Cl) while ρ = -3.26 for electron-donating substituents (X = OH, OCH 3 and CH 3 ). The Brønstedtype plot is also nonlinear with a change in slope from a small value (β nuc = 0.50) to a large value (β nuc = 1.29 at pK a = 4.58). This change could be interpreted in terms of a change in mechanism from a polar S N Ar process to a single electron transfer. On the other hand, the experimental data show that the rate constants (k 1 ) values exhibit good correlation with the oxidation potentials (E o ) of the aniline nucleophiles and are consistent with the suggested mechanism.

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Kinetics and mechanism of the pyridinolysis of aryl dithiobenzoates in acetonitrile

Cited by 34 publications

References 35 publications

Nonlinear Taft Polar Free Energy Relationship: Reactions of N‐Substituted Benzyl Amines with Benzyl Bromide in Methanol

Nonlinear Taft Polar Free Energy Relationship: Reactions of N‐Substituted Benzyl Amines with Benzyl Bromide in Methanol

Nonlinear Brønsted and Hammett Correlations Associated with Reactions of 4‐Chloro‐7‐nitrobenzofurazan with Anilines in Dimethyl Sulfoxide Solution

Single electron transfer in S_NAr process: Reactions of 2,4,6-tris(trifluoromethanesulfonyl)anisole with anilines in dimethyl sulfoxide

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Kinetics and mechanism of the pyridinolysis of aryl dithiobenzoates in acetonitrile

Cited by 34 publications

References 35 publications

Nonlinear Taft Polar Free Energy Relationship: Reactions of N‐Substituted Benzyl Amines with Benzyl Bromide in Methanol

Nonlinear Taft Polar Free Energy Relationship: Reactions of N‐Substituted Benzyl Amines with Benzyl Bromide in Methanol

Nonlinear Brønsted and Hammett Correlations Associated with Reactions of 4‐Chloro‐7‐nitrobenzofurazan with Anilines in Dimethyl Sulfoxide Solution

Single electron transfer in SNAr process: Reactions of 2,4,6-tris(trifluoromethanesulfonyl)anisole with anilines in dimethyl sulfoxide

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Single electron transfer in S_NAr process: Reactions of 2,4,6-tris(trifluoromethanesulfonyl)anisole with anilines in dimethyl sulfoxide