Some tentative explanations for the enthalpy–entropy compensation effect in chemical kinetics: from experimental errors to the Hinshelwood-like model

Perez‐Benito, Joaquin F.

doi:10.1007/s00706-012-0842-1

Cited by 34 publications

(32 citation statements)

References 34 publications

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“…This kind of correlation between Δ H and Δ S is termed the enthalpy and entropy compensation effect , because of the cancellation of the 2 terms Δ H and −TΔ S in the Gibbs relationship for the physicochemical process of interest

Δ G_{OA} = - R T ln K_{OA} = Δ H_{OA} - T Δ S_{OA}

where Δ G OA is Gibbs free energy for the octanol‐to‐air partitioning process. These effects have been observed for many chemical and biological reactions for groups of similar compounds and Henry's law constants for PCBs . However, others have cautioned that such phenomena may be a statistical artifact in the experimental data .…”

Section: Resultsmentioning

confidence: 97%

“…where DG OA is Gibbs free energy for the octanol-to-air partitioning process. These effects have been observed for many chemical and biological reactions for groups of similar compounds [28][29][30][31] and Henry's law constants for PCBs [27]. However, others have cautioned that such phenomena may be a statistical artifact in the experimental data [32].…”

Section: Temperature Dependencementioning

confidence: 99%

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Evaluation of the three‐phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (K_OW, K_OA, and K_AW) for volatile methylsiloxanes and trimethylsilanol

Kropscott

2014

Enviro Toxic and Chemistry

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Partitioning equilibria and their temperature dependence of chemicals between different environmental media are important in determining the fate, transport, and distribution of contaminants. Unfortunately, internally consistent air/water (KAW), 1-octanol/air (KOA), and 1-octanol/water (KOW) partition coefficients, as well as information on their temperature dependence, are scarce for organosilicon compounds because of the reactivity of these compounds in water and octanol and their extreme partition coefficients. A newly published 3-phase equilibrium method was evaluated for simultaneous determination of the temperature dependence of KAW, KOA, and KOW of 5 volatile methylsiloxanes (VMS) and trimethylsilanol (TMS) in a temperature range from 4 °C to 35 °C. The measured partition coefficients at the different temperatures for any given compound, and the enthalpy and entropy changes for the corresponding partition processes, were all internally consistent, suggesting that the 3-phase equilibrium method is suitable for this type of measurement. Compared with common environmental contaminants reported in the literature, VMS have enthalpy and entropy relationships similar to those of alkanes for air/water partitioning and similar to those of polyfluorinated compounds for octanol/air partitioning, but more like those for benzoates and phenolic compounds for octanol/water partitioning. The temperature dependence of the partition coefficients of TMS is different from those of VMS and is more like that of alcohols, phenols, and sulfonamides. Environ Toxicol Chem 2014;33:2702–2710. © 2014 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc.

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Δ G_{OA} = - R T ln K_{OA} = Δ H_{OA} - T Δ S_{OA}

Section: Resultsmentioning

confidence: 97%

Section: Temperature Dependencementioning

confidence: 99%

Evaluation of the three‐phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (K_OW, K_OA, and K_AW) for volatile methylsiloxanes and trimethylsilanol

Kropscott

2014

Enviro Toxic and Chemistry

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“…Therefore, the magnitudes of ( T iso − T exp ) δ∆ S ≠ can be a good approximation of the variations of the free energy of activation, δ∆ G ≠ exp , which is the characteristic of the effects of substituents on the S N Ar reactions. At the same time, the IKR (Equation ) is real kinetic enthalpy—entropy compensation effect due to T comp > T exp …”

Section: Resultsmentioning

confidence: 99%

Simple method for determining of the isokinetic temperature value for the S_NAr reactions in solution

Vlasov

2017

J of Physical Organic Chem

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The changes of the free energy of activation δΔG ≠ exp and the activation entropy δΔS ≠ in the framework of the isokinetic relationship δΔG ≠ exp versus (T iso − T exp ) δΔS ≠ were explored quantitatively to predict the isokinetic temperature T iso for the aromatic nucleophilic substitution reactions in solution.KEYWORDS activation parameters, isokinetic relationship, isokinetic temperature, reaction mechanism, S N Ar reactions, substituent effects, transition state | INTRODUCTIONSignificant effort in recent decades has been made in the determination of the isokinetic relationship (IKR) in the S N Ar reactions. [1][2][3][4][5][6][7][8][9][10] The existence of this extra-thermodynamic tool infers a possible change in the reaction mechanism at some IKRs, [1] or the reactions occur by identical mechanism at the existence of a single IKR. [11,12] Recently, it was shown the possibility to predict the isokinetic temperature T iso based on the variation in the internal enthalpy of activation, δΔH ≠ int , and also in the parameters δΔS ≠ and δΔG ≠ for the S N Ar reactions of the benzene derivatives at structural changes to the nucleophiles and substrates (Equation 1).[13]The compensation temperature, T comp , is the slope in the linear relationship between the changes of the enthalpy and entropy of activation, ΔH ≠ and ΔS ≠ , for the series of the similar reactions [14] according to Equation 2.It should be noticed that the external part, δΔH solution, [28] in which step k 1 is rate determining. [28,31] Therefore, the analysis of the changes in the free energy of activation, δΔG ≠ , and also the entropy of activation, δΔS ≠

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“…The observed isokinetic temperature (β) values most probably suggest that the reactions are controlled by entropy factors as suggested by earlier literature reports. At this point it is worth mentioning that Leffler's approach for the determination of isokinetic temperature (β) is criticized by some research groups [69,70], yet the theory is used by several other research groups [71][72][73][74].…”

Section: Enthalpy (δH # ) and Entropy Of Activation (δS # ) Relationsmentioning

confidence: 99%

Trichloroisocyanuric acid and NaNO2 mediated nitration of indoles under acid-free and Vilsmeier–Haack conditions: synthesis and kinetic study

et al. 2019

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This study deals with the synthetic and kinetic aspects of trichloroisocyanuric acid (TCCA) and NaNO 2 mediated nitration of indoles in aqueous acetonitrile media under acid-free and Vilsmeier-Haack conditions (using N,N′-dimethyl amides) conditions. Nitration of indoles revealed second order kinetics, with a first order dependence on [indole] and [nitrating agent] ([TCCA]/[NaNO 2 ], [(TCCA-DMF)]/[NaNO 2 ] or [(TCCA-DMA)]/[NaNO 2 ], in which [NaNO 2 ] far excess over other reagents). Reactions followed overall second order kinetics with first order in [reagent] and [indole] under the experimental conditions. Isokinetic temperature (β) values were obtained from Leffler's equation for different kinetic protocols (β = 303 K (TCCA-NaNO 2 ); 303 K (TCCA-DMF)/NaNO 2 ; and 244 K (TCCA-DMA)/NaNO 2 ). These values are the experimental temperature range (303-323 K) indicating that the entropy factors are probably more important in controlling the reaction.

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Some tentative explanations for the enthalpy–entropy compensation effect in chemical kinetics: from experimental errors to the Hinshelwood-like model

Cited by 34 publications

References 34 publications

Evaluation of the three‐phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (K_OW, K_OA, and K_AW) for volatile methylsiloxanes and trimethylsilanol

Evaluation of the three‐phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (K_OW, K_OA, and K_AW) for volatile methylsiloxanes and trimethylsilanol

Simple method for determining of the isokinetic temperature value for the S_NAr reactions in solution

Trichloroisocyanuric acid and NaNO2 mediated nitration of indoles under acid-free and Vilsmeier–Haack conditions: synthesis and kinetic study

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Some tentative explanations for the enthalpy–entropy compensation effect in chemical kinetics: from experimental errors to the Hinshelwood-like model

Cited by 34 publications

References 34 publications

Evaluation of the three‐phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (KOW, KOA, and KAW) for volatile methylsiloxanes and trimethylsilanol

Evaluation of the three‐phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (KOW, KOA, and KAW) for volatile methylsiloxanes and trimethylsilanol

Simple method for determining of the isokinetic temperature value for the SNAr reactions in solution

Trichloroisocyanuric acid and NaNO2 mediated nitration of indoles under acid-free and Vilsmeier–Haack conditions: synthesis and kinetic study

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Product

Resources

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Evaluation of the three‐phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (K_OW, K_OA, and K_AW) for volatile methylsiloxanes and trimethylsilanol

Evaluation of the three‐phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (K_OW, K_OA, and K_AW) for volatile methylsiloxanes and trimethylsilanol

Simple method for determining of the isokinetic temperature value for the S_NAr reactions in solution