Deviation of Dielectric Constant from Ideality for Certain Binary Solvent Systems

Amirjahed, A.K.; Blake, Martin I.

doi:10.1002/jps.2600640936

Cited by 6 publications

(5 citation statements)

References 1 publication

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“…Herein, in the absence of availability of the experimental values of the dielectric constant of the mixture, it was estimated using an empirical method. 18 Though the use of empirical estimates is not the best option, it allows the exploration of the concept of continuous change in the polarity of the solvent. Furthermore, these approaches have an overall average percentage deviation between the estimated experimental values at less than 2%.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Considering that the solvent’s polarity influences the K T , finding a way to calculate the polarity or the dielectric constant of a mixture (ε) is of interest. Herein, in the absence of availability of the experimental values of the dielectric constant of the mixture, it was estimated using an empirical method . Though the use of empirical estimates is not the best option, it allows the exploration of the concept of continuous change in the polarity of the solvent.…”

Section: Resultsmentioning

confidence: 99%

Section: Estimation Of the Dielectric Constant Of The Solvent Mixturementioning

confidence: 99%

“…In understanding the effects polarity has on the tautomerization equilibrium, the ability to calculate the dielectric constant of a mixture at various polarizable conditions can give a numerical range on how the equilibrium changes as the solvent’s polarity changes. Amirjahed and Blake derived an empirical expression that related the mole fractions, dielectric constants, and the volumes of the binary solvent mixture to estimate the overall dielectric constant of the mixture as follows. where ε is the net dielectric constant of the mixture, the subscript 1 represents the more polar solvent, subscript 2 represents the less polar solvent, and X is the mole fractions of the two solvents. The coefficients a , b , c , and d are further calculated by using the dielectric constant ( D ) and volume ( V ) of each of the solvents as follows. For the solvents dimethyl sulfoxide and chloroform, a dielectric constant of 46.7 and 4.8 D were used, respectively, and the effect of deuteration on the dielectric constants was not considered.…”

Section: Description Of the Experimentsmentioning

confidence: 99%

“…This work further takes advantage of the empirical tools available for the estimation of the dielectric constant of a solvent mixture, , and thus relates the change in the K T directly with solvent polarity using the Onsager–Kirkwood theory . This theory describes how the polarizability of a molecule is affected by the polarity of the solvent.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Keto–Enol Tautomerization of Acetylacetone in Mixed Solvents by NMR Spectroscopy. A Physical Chemistry Experiment on the Application of the Onsager-Kirkwood Model for Solvation Thermodynamics

Cortney

Krishnan

2020

J. Chem. Educ.

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Keto–enol tautomerism is a fundamental concept that examines the migration of a proton between two constitutional isomers, the keto and enol tautomer. Many experiments have been proposed to understand the concept behind Meyer’s Rule, which states that the keto tautomer is favored as the solvent polarity increases. However, all the experiments have only been performed in a single solvent. A new physical chemistry experiment is introduced to determine tautomerization equilibrium in binary solvent mixtures using nuclear magnetic resonance (NMR) spectroscopy, by systematically varying the molar ratio of the solvents. This approach allows the students to explore the variation of the polarity of the solvent system as a continuous variable. Furthermore, using an empirical method, the solvent polarity at any binary solvent condition can be converted to an effective dielectric constant of the sample. Because of this ability, the keto–enol tautomerization equilibrium constant can be directly related to the solvation Gibbs energy using the Onsager–Kirkwood theory. Detailed experimental procedures for the direct adaptation of the experiment using a high-resolution or desktop NMR spectrometer is provided in the Supporting Information.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Estimation Of the Dielectric Constant Of The Solvent Mixturementioning

confidence: 99%

Section: Description Of the Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Keto–Enol Tautomerization of Acetylacetone in Mixed Solvents by NMR Spectroscopy. A Physical Chemistry Experiment on the Application of the Onsager-Kirkwood Model for Solvation Thermodynamics

Cortney

Krishnan

2020

J. Chem. Educ.

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The predictive accuracy of secondary chemical shifts is more affected by protein secondary structure than solvent environment

2010

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Biomolecular NMR spectroscopy frequently employs estimates of protein secondary structure using secondary chemical shift (Deltadelta) values, measured as the difference between experimental and random coil chemical shifts (RCCS). Most published random coil data have been determined in aqueous conditions, reasonable for non-membrane proteins, but potentially less relevant for membrane proteins. Two new RCCS sets are presented here, determined in dimethyl sulfoxide (DMSO) and chloroform:methanol:water (4:4:1 by volume) at 298 K. A web-based program, CS-CHEMeleon, has been implemented to determine the accuracy of secondary structure assessment by calculating and comparing Deltadelta values for various RCCS datasets. Using CS-CHEMeleon, Deltadelta predicted versus experimentally determined secondary structures were compared for large datasets of membrane and non-membrane proteins as a function of RCCS dataset, Deltadelta threshold, nucleus, localized parameter averaging and secondary structure type. Optimized Deltadelta thresholds are presented both for published and for the DMSO and chloroform:methanol:water derived RCCS tables. Despite obvious RCCS variations between datasets, prediction of secondary structure was consistently similar. Strikingly, predictive accuracy seems to be most dependent upon the type of secondary structure, with helices being the most accurately predicted by Deltadelta values using five different RCCS tables. We suggest caution when using Deltadelta-based restraints in structure calculations as the underlying dataset may be biased. Comparative assessment of multiple RCCS datasets should be performed, and resulting Deltadelta-based restraints weighted appropriately relative to other experimental restraints.

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Dielectric constant of mixed solvents based on perturbation theory

Neumaier

Schilling

Bardow

et al. 2022

Fluid Phase Equilibria

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Deviation of Dielectric Constant from Ideality for Certain Binary Solvent Systems

Cited by 6 publications

References 1 publication

Keto–Enol Tautomerization of Acetylacetone in Mixed Solvents by NMR Spectroscopy. A Physical Chemistry Experiment on the Application of the Onsager-Kirkwood Model for Solvation Thermodynamics

Keto–Enol Tautomerization of Acetylacetone in Mixed Solvents by NMR Spectroscopy. A Physical Chemistry Experiment on the Application of the Onsager-Kirkwood Model for Solvation Thermodynamics

The predictive accuracy of secondary chemical shifts is more affected by protein secondary structure than solvent environment

Dielectric constant of mixed solvents based on perturbation theory

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