The “Basicity Method” for Estimating Tautomer Ratio: A Radical Re‐Appraisal

Taylor, Peter J.

doi:10.1002/9783527658824.ch12

Cited by 5 publications

(9 citation statements)

References 56 publications

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“…In turn, these complexes have been reported to react with -OH groups and form several lactams and lactims with different colouration 34,35 . and the pH (and thus the presence of ME and MeOD) seems to influence the tautomer ratio between them [36][37] .…”

Section: Stability Of Ea With Me and Zad Under Different Conditionsmentioning

confidence: 99%

Role of Ethanolamine on the Stability of a Sol–Gel ZnO Ink

et al. 2017

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This work presents a detailed structural and chemical characterization of the system formed by zinc acetate dihydrate (ZAD) and ethanolamine (EA) with methoxyethanol (ME), in order to describe its stability. The origin of the mixture degradation during storage at room conditions is analyzed. Theoretical calculations of the frontier orbitals of the system ZAD plus EA under interaction with ME and CO 2 are used to deduce energy levels and stability of the different molecules appearing in the ZAD-EA-ME system. The models were tested as potential energy minimum and their photo-absorption spectra were simulated. The dimerization process leading from the simplest configuration to the most abundant one is also theoretically analyzed and used to describe the effect of the nuclearity raise on the mixture stability. Our results explain the experimental observations and provide a better understanding of the role played by EA in the formation of ZnO and, consequently, allow optimizing the technological processes to prepare these films.

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Section: Stability Of Ea With Me and Zad Under Different Conditionsmentioning

confidence: 99%

Role of Ethanolamine on the Stability of a Sol–Gel ZnO Ink

et al. 2017

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“…The corresponding values of ∆G are 0.3, 1.3 and 2.7 kcal/mol respectively, which indicates predominance of the keto tautomer as predicted by the calculations. The results for water are approximate (based on the pKa approximation 49,51,52 ) and indicate a ratio 1E/1K < 1/900, i.e. the equilibrium is practically switched towards the keto tautomer.…”

Section: Resultsmentioning

confidence: 87%

Favipiravir Tautomerism: A Short Theoretical Report

Antonov

2020

Preprint

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There is no experimental data about the tautomerism of Favipiravir (T-705). Therefore its tautomeric state was predicted by using density functional theory in gas phase and in solution (toluene, acetonitrile and water). The solvent effect was described by means of the Polarizable Continuum Model. The results have shown that the enol form is strongly dominating in both gas phase and solution. In order to validate the theoretical predictions, 2-hydroxy pyridine and 2-hydroxy pyrazine were also included in the set of studied compounds. The available experimental data for their tautomerism are in very good agreement with the theoretical predictions, which validate the conclusions made for T-705.

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“…It terms of the above requirement, (b) is the ''best fit'' option with (a) closely behind it, despite their use for log K T of an equation that uses a nonsignificant π* term. It happens that log K T was measured by the ''basicity method'' [42] to give a value that was later adjusted to 1.44 by the use of correction factors [43] that have proved accurate elsewhere [17]. This value is much closer to 1.60 than 0.93 and helps to suggest that Eq.…”

Section: Three-way Tautomerism In the Pyrazolone 25mentioning

confidence: 96%

“…Table 11.9. b The ''modified basicity method'' [17] gives log K T = 1.42 for this equilibrium [42,43].…”

Section: Three-way Tautomerism In the Pyrazolone 25mentioning

confidence: 99%

“…It covers three equilibria, two of which are inaccessible to the ''basicity method'' essentially because their ''common cations'' when approached from one or both directions are severely disfavored, a different protonation route being preferred [43]; see Section 12.6. In addition, the type of compound it represents, which may be summarized generically as 26 and displays a myriad of tautomeric complications, is notorious not only for the complexity of its behavior but also for its experimental intractability, especially where solubility is concerned.…”

Section: Three-way Tautomerism In the Pyrazolone 25mentioning

confidence: 99%

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The Scope and Limitations of LSER in the Study of Tautomer Ratio

Taylor

2013

Tautomerism

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A change in solvent commonly gives rise to major changes in the rates and equilibria of chemical reactions. While solvent effects have long been studied, their quantitative analysis is a relatively recent achievement. The crucial step in this development lies in the solvatochromic approach, above all associated with Taft and coworkers [1, 2], which is a multiple regression technique that relies on giving numerical values to the solvent properties concerned. In this methodology, spectroscopic shifts, mostly ultraviolet (UV) or nuclear magnetic resonance (NMR) but sometimes of other sorts, are used to generate values for each property by comparison with a standard nonpolar solvent, for example, cyclohexane, as described in the following sections. The thermodynamic status of these shifts is uncertain: they were originally supposed to be free-energy related but they are not free energies per se and some have been demonstrated [3] to represent blends of G with H. As used in linear solvation energy relationships (LSER), however (see discussion below), the values themselves are unexceptionable provided that they are proportional to the energy of the molecular property they purport to describe, and even their precise thermodynamic status is of muted importance if they are mutually orthogonal. Essentially, LSER is an empirical topic and here will be treated as such. The Taft-Kamlet LSER MethodologyThe overall LSER equation in its most comprehensive form [1] is set out as follows:where XYZ is the free energy of the process, rate, or equilibrium, in a given solvent, XYZ 0 is the value expected for the solvent cyclohexane, and the remaining terms list * This author is deceased.Tautomerism: Methods and Theories, First Edition. Edited by Liudmil Antonov.

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The “Basicity Method” for Estimating Tautomer Ratio: A Radical Re‐Appraisal

Cited by 5 publications

References 56 publications

Role of Ethanolamine on the Stability of a Sol–Gel ZnO Ink

Role of Ethanolamine on the Stability of a Sol–Gel ZnO Ink

Favipiravir Tautomerism: A Short Theoretical Report

The Scope and Limitations of LSER in the Study of Tautomer Ratio

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