Rapid relaxation NMR measurements to predict rate coefficients in ionic liquid mixtures. An examination of reaction outcome changes in a homologous series of ionic liquids

Morris, Daniel C.; Prescott, Stuart W.; Harper, Jason B.

doi:10.1039/d0cp06066f

Cited by 7 publications

(15 citation statements)

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“…It is worth noting that other correlations have been attempted with rate constant data previously, including with NMR relaxation data and charge distribution in the ionic species . In the former case, the correlation was empirical and the physical origin underlying the correlation was not clear, but the correlation was useful nonetheless in predicting reaction outcome.…”

Section: Resultsmentioning

confidence: 99%

“…While it might be possible to evaluate potential ionic liquid solvents based on molecular level interactions in solution (including those based on structure of the solvent − ), this process is not quantitative. There have been attempts to provide quantitative analysis using measurements such as solvent parameters (including Kamlet–Taft parameters ,,,− and Gutmann donor numbers), NMR relaxation data, and analysis of charge distribution in the ionic species, along with machine learning methods on a large data set . While each of these has proved useful in some contexts, the information gathered is reaction specific, and the quality of the correlations varies.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Ionic Liquids on the Nucleofugality of Chloride

et al. 2021

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The nucleofugality of chloride has been measured in solvent mixtures containing ionic liquids for the first time, allowing reactivity in these solvents to be put in context with molecular solvents. Using well-described electrofuges, solvolysis rate constants were determined in mixtures containing different proportions of ethanol and the ionic liquid 1-butyl-3-methylimidazolium bis-(trifluoromethanesulfonyl)imide; the different solvent effects observed as the mixture changed could be explained using interactions of the ionic liquid with species along the reaction coordinate, determined using temperature dependent kinetic studies. The solvolysis data allowed determination of the nucleofugality of chloride in these mixtures, which varied with the proportion of salt in the reaction mixture, demonstrating quantitatively the importance of the amount of ionic liquid in the reaction mixture in determining reaction outcome. Nucleofugality data for chloride were determined in seven further ionic liquids, with the reactivity shown to vary over more than an order of magnitude. This outcome illustrates that the components of the ionic liquid are critical in determining reaction outcome. Overall, this work quantitatively extends the understanding of solvent effects in ionic liquids and demonstrates the potential for such information to be used to rationally select an ionic liquid to control reaction outcome.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Ionic Liquids on the Nucleofugality of Chloride

et al. 2021

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“…As introduced above, mixtures containing different propor‐ tions of one of the ionic liquids 4 in acetonitrile, with a constant concentration of pyridine 1 (approx. 0.5 M), were examined; the pyridine 1 concentration used matches that used in kinetics experiments [34] . The values of the χ IL were increased in increments of approx.…”

Section: Resultsmentioning

confidence: 99%

“…Importantly, in recent work considering the relationship between the rate coefficient for a well‐studied reaction that proceeds through a bimolecular substitution process (that between pyridine 1 and benzyl bromide 2 , Scheme 1) and transverse NMR relaxation time ( T 2 ), [33] a dependence on the origin of solvent effects was noted with the nature of the ionic liquid mixture [34] . In all cases in which the reaction was carried out in mixtures containing a high proportion of one of the homologous series 4 (Figure 1), the energetic origins of the changes in rate coefficient were the same and consistent with reported observations [26,35–38] – an increase in enthalpy of activation was outweighed by an increase in the entropy of activation.…”

Section: Introductionmentioning

confidence: 99%

Diffusion Measurements To Understand Dynamics and Structuring in Solutions Involving a Homologous Series of Ionic Liquids

Morris

Morris²,

Price

et al. 2023

ChemPhysChem

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The self-diffusion coefficients of each of the components in mixtures containing pyridine and each of the homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imides in acetonitrile were determined using NMR diffusometry (i. e., Pulsed Gradient Spin Echo). The nature of solvation was found to change significantly with the proportion of salt in the mixtures. Increased diffusion coefficients (when corrected for viscosity) for the molecular components were observed with increasing proportion of ionic liquid and with increasing alkyl chain length on the cation. Comparison of the molecular solvents suggests increased interactions in solution of the pyridine with other components of the mixture, consistent with the proposed interactions shown previously to drive changes in reaction kinetics. Discontinuities were seen in the diffusion data for each species in solution across different ionic liquids between the hexyl and octyl derivatives, suggesting a change in the structuring in solution as the alkyl chain on the cation changes and demonstrating the importance of such when considering homologous series.

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“…† The ionic liquid (IL) 1-ethyl-3-methyl-imidazolium bis(triuoromethanesulfonyl)imide ([EMIM][TFSI]) was synthesized according to a previous report. 35…”

Section: Methodsmentioning

confidence: 99%

Dynamic and mechanically robust and ultrafast healable ionogel for nerve fiber-inspired signal transmitter

Liu

Pei

et al. 2022

J. Mater. Chem. A

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Rapid relaxation NMR measurements to predict rate coefficients in ionic liquid mixtures. An examination of reaction outcome changes in a homologous series of ionic liquids

Abstract: A series of ionic liquids based on the 1-alkyl-3-methylimidazolium cations were examined as components of the solvent mixture for a bimolecular substitution process. The effects on both the rate coefficient...

Cited by 7 publications

References 62 publications

Effects of Ionic Liquids on the Nucleofugality of Chloride

Effects of Ionic Liquids on the Nucleofugality of Chloride

Diffusion Measurements To Understand Dynamics and Structuring in Solutions Involving a Homologous Series of Ionic Liquids

Dynamic and mechanically robust and ultrafast healable ionogel for nerve fiber-inspired signal transmitter

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