Determination of local effects for chloroaluminate ionic liquids on Diels–Alder reactions

Acevedo, Orlando

doi:10.1016/j.jmgm.2009.04.003

Cited by 22 publications

(23 citation statements)

References 55 publications

(48 reference statements)

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“…In many cases, the explicit treatment of (at least some) IL ions should be considered (i.e., microsolvation), and the calculations may rather focus on, e.g., a cluster approach for the investigation of reactions in ILs, as seen in Chapter 3. A prominent example for such calculations is reported on the Diels–Alder reaction between methyl acrylate and cyclopentadiene in 1‐ethyl‐3‐methylimidazolium chloroaluminate ionic liquids . By analyzing the lowest‐energy transition‐state structures of a set of clusters, it could be shown that the catalyzing effect of the imidazolium cation lies in its hydrogen bonding ability, which withdraws the electron density from the dienophile, making it, therefore, more prone to react with the diene.…”

Section: Spontanous Events and Reactionsmentioning

confidence: 99%

Multiresolution calculation of ionic liquids

Kirchner

Hollóczki

Lopes

et al. 2014

WIREs Comput Mol Sci

115

165

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Ionic liquids-which are special solvents composed entirely of ions-are difficult albeit interesting to study for several reasons. Owing to the many possible cation and anion combinations that form ionic liquids, common properties are hard to classify for them, which makes the theoretical investigation crucial for ionic liquids. The system size, the amount of possible isomers including cation-anion orientation and coordination, as well as the rotation of the side chain(s) prevent the use of high-level electronic structure methods, and density functional theory is the method of choice. Dispersion forces-although they are small compared to electrostatics-play a major role in ionic liquids; therefore, methods that describe such kind of interplay are preferred. Between the cation and the anion, there is a sizable charge transfer, which has important consequences for molecular dynamics simulations and force field development. Already based on the first generation of force fields important discoveries were made, namely that ionic liquids are nanostructured. Moreover, it was possible to predict that their distillation is possible. Throughout the construction of these force fields, transferability was taken into account which allowed them to describe homologous series. For studying reactions in ionic liquid (IL) media, continuum models were found to improve the results. Ab initio molecular dynamics (AIMD) and quantum mechanics (QM)/molecular mechanics (MM) approaches are well suited for spontaneous events. In case of very large systems, such as cellulose in ionic liquids, coarse-grained methods are providing insight and are applied more frequently. This makes ionic liquids real multiscalar systems.

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Section: Spontanous Events and Reactionsmentioning

confidence: 99%

Multiresolution calculation of ionic liquids

Kirchner

Hollóczki

Lopes

et al. 2014

WIREs Comput Mol Sci

115

165

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“…The main absorption mechanism is the π electron interaction between C33 and N11, and a weak hydrogen bond between CO 2 and [Apeim] + . 4 ] -) је јонска течност (IL) која везује CO 2 . Ово једињење је систематски проучавано на нивоу B3LYP/6-311++G  и mp2/6-311++G  .…”

Section: Discussionunclassified

“…The energy change (ΔE(IL)) between an IL and the isolated ions is commonly used to estimate the interaction energy between the ion-pair of an IL, which, in the present case, can be calculated from 4 ] -are mainly displayed as hydrogen bonds (HBs) and the energy of these HBs is far less than the value of ΔE(IL), so there must be other stronger interaction forces between the ion-pair besides these HBs, and it is necessary to perform further NBO and AIM investigations. Table I also shows that the relative energies of A IL-CO 2 and B IL-CO 2 are -21.01 and 31.76 kJ mol -1 , respectively, i.e., A IL capturing CO 2 is an exothermic reaction while B IL capturing CO 2 is an endothermic reaction.…”

Section: Energies Of the Stable Speciesmentioning

confidence: 99%

Investigations of 1-(4-propylamino)-3-ethyl imidazolium tetrafluoroborate ionic liquid capturing CO2

Yang

Zhao

Sun

2013

JSCS

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1-(4-propylamino)-3-ethyl imidazolium ([Paeim]+) Tetrafluoroborate([BF4]-) Ionic liquid (IL), capturing CO2, was explored systematically at B3LYP/6-311++G** and mp2/6-311++G** level. The stable geometries of ILs and capture products were optimized, the energies of these geometries were obtained and corrected by Zero-point-vibration-energy and basis set superposition error correction. The results show that the interactions between [Paeim]+and [BF4]-are mainly displayed as hydrogen bonds, but the interaction energies exceeds -328 kJ/mol. Further analysis found that the interactions are reinforced by charge dispersion and charge redistribution of ion-pair, and that electrostatic attraction contributes much to the interaction energies. This IL system capturing CO2belongs to the class of physical sorption with 1:1 molar absorption ratio, the absorption energy is nearly -18kJ/moland thus this IL may have low energy consumption when regenerated from IL-CO2

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“…While "ionic liquid effects" that enhance chemical reactivity can range from weak to significant, optimizing these solvent effects requires a better understanding of the contributing molecular factors [35][36][37]. Our group has provided fundamental insight through the use of on-the-fly mixed quantum mechanical and molecular mechanical (QM/MM) calculations coupled to free-energy perturbation theory and Monte Carlo sampling (FEP/MC) to simulate multiple organic reactions in ionic liquids [38], including the substitution [39], elimination [40,41], pericyclic [42,43] and rearrangement [44] reaction classes. Of particular interest here is the Diels-Alder reaction, which is known to be exceptionally sensitive to solvent effects in terms of both rates and product selectivity [45,46].…”

Section: Introductionmentioning

confidence: 99%

Accurate Diels-Alder Energies and Endo Selectivity in Ionic Liquids Using the OPLS-VSIL Force Field

Velez

Doherty

Acevedo

2020

IJMS

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Our recently developed optimized potentials for liquid simulations-virtual site ionic liquid (OPLS-VSIL) force field has been shown to provide accurate bulk phase properties and local ion-ion interactions for a wide variety of imidazolium-based ionic liquids. The force field features a virtual site that offloads negative charge to inside the plane of the ring with careful attention given to hydrogen bonding interactions. In this study, the Diels-Alder reaction between cyclopentadiene and methyl acrylate was computationally investigated in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6], as a basis for the validation of the OPLS-VSIL to properly reproduce a reaction medium environment. Mixed ab initio quantum mechanics and molecular mechanics (QM/MM) calculations coupled to free energy perturbation and Monte Carlo sampling (FEP/MC) that utilized M06-2X/6-31G(d) and OPLS-VSIL gave activation free energy barriers of 14.9 and 16.0 kcal/mol for the endo-cis and exo-cis Diels-Alder reaction pathways, respectively (exptl. ΔH‡ of 14.6 kcal/mol). The endo selectivity trend was correctly predicted with a calculated 73% endo preference. The rate and selectivity enhancements present in the endo conformation were found to arise from preferential hydrogen bonding with the exposed C4 ring hydrogen on the BMIM cation. Weaker electronic stabilization of the exo transition state was predicted. For comparison, our earlier ±0.8 charge-scaled OPLS-2009IL force field also yielded a ΔG‡ of 14.9 kcal/mol for the favorable endo reaction pathway but did not adequately capture the highly organized solvent interactions present between the cation and Diels-Alder transition state.

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Determination of local effects for chloroaluminate ionic liquids on Diels–Alder reactions

Cited by 22 publications

References 55 publications

Multiresolution calculation of ionic liquids

Multiresolution calculation of ionic liquids

Investigations of 1-(4-propylamino)-3-ethyl imidazolium tetrafluoroborate ionic liquid capturing CO2

Accurate Diels-Alder Energies and Endo Selectivity in Ionic Liquids Using the OPLS-VSIL Force Field

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