Dynamics of the Gas-Phase Reactions of Fluoride Ions with Chloromethane

and, Laurence A. Angel; Ervin, Kent M.

doi:10.1021/jp0042866

Cited by 71 publications

(99 citation statements)

References 59 publications

(124 reference statements)

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“…Besides the well-known Walden inversion mechanism, there is a front-side attack pathway, which goes over a high energy barrier and results in retention of configuration. This front-side attack mechanism is much less studied than the Walden inversion [10][11][12][13] . Due to the high barrier of the former, the S N 2 reactions are known to proceed via Walden inversion at low collision energies (E coll ) and the front-side attack pathway may open at higher E coll .…”

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confidence: 99%

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

2015

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Stereo-specific reaction mechanisms play a fundamental role in chemistry. The back-side attack inversion and front-side attack retention pathways of the bimolecular nucleophilic substitution (S N 2) reactions are the textbook examples for stereo-specific chemical processes. Here, we report an accurate global analytic potential energy surface (PES) for the F À þ CH 3 Cl S N 2 reaction, which describes both the back-side and front-side attack substitution pathways as well as the proton-abstraction channel. Moreover, reaction dynamics simulations on this surface reveal a novel double-inversion mechanism, in which an abstraction-induced inversion via a FH Á Á Á CH 2 Cl À transition state is followed by a second inversion via the usual [F Á Á Á CH 3 Á Á Á Cl] À saddle point, thereby opening a lower energy reaction path for retention than the front-side attack. Quasi-classical trajectory computations for the F À þ CH 3 Cl(n 1 ¼ 0, 1) reactions show that the front-side attack is a fast direct, whereas the double inversion is a slow indirect process.

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confidence: 99%

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

2015

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“…This result is also consistent with the prediction that the hyperconjugative interaction plays an important role in TS1-2 system, although steric repulsion does also exist. For example, our theoretical results ( Table 2) show that the largest stabilization energies E (2) of LP(O) ¡ *(C-Cl*) exist in TS1-3 system, while TS1-4 has the smallest E (2) in the interaction, compared with corresponding TS's electronic energies. As a comparison, TS1-Cl has more charge transferred from the ClO moiety to the CHCl 3 fragment than the TS1-3, by 0.048 a.u.…”

Section: Im1-clmentioning

confidence: 91%

“…1 Over the past decades, much work has been devoted to the study of nucleophilicity and leaving-group ability. [2][3][4][5][6][7] These studies investigated the effect of nucleophile and leaving group on the barrier to S N 2 reactions. Recently, Bickelhaupt et al, exploring the gas-phase reactions of the type in eq.…”

Section: Introductionmentioning

confidence: 99%

Gas-phase reaction of ClO⁻with CH_nCl_4-_n(n= 0, 1, 2, 3) and CX₃H (X = F, Cl and Br): Substituent effect from a comparative study

et al. 2014

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Substituent effects on reactivity are studied using the hybrid B3LYP and BHandHLYP methods of density functional theory with the aug-cc-pVDZ basis set. The chosen testing models includes two very representative reactions in chemical research, the bimolecular nucleophilic substitution (S N 2) reaction and the deprotonation reaction, in which the former is represented by ClO − + CH n Cl 4-n (n = 0, 1, 2, 3), and the latter is based on reactions of ClO − with CX 3 H (X = F, Cl, and Br). Our theoretical findings suggest that a heavier substituent X in substrate results in a higher activation energy, a slower S N 2 reaction, but a faster deprotonation reaction. Those are well confirmed by some presented results from bond orders, second-order perturbative energy E (2) , and activation strain model analysis. Moreover, we have further explored the reactivity difference derived from substituent effects in term of the relationships of reactive barrier with the charges transferred and the leavingbond distance in TSs, respectively, especially the TSs in S N 2 reactions. Again, the rate constants at 298-1000 K are also evaluated for the S N 2 reactions presented through the transition state theory.Key words: anion ClO − , substituent effect, density functional theory (DFT).Résumé : L'effet des substituants sur la réactivité a été étudié par l'intermédiaire des fonctionnelles hybrides B3LYP et BHandHLYP de la théorie de la fonctionnelle de la densité, en utilisant la base aug-cc-pVDZ. Le modèle d'étude choisi comprend deux réactions très représentatives en chimie, la substitution nucléophile bimoléculaire (S N 2) et la réaction de déprotonation, qui sont respectivement représentées par la réaction ClO − + CH n Cl 4-n (n = 0, 1, 2, 3) et par la réaction de l'anion ClO − avec CX 3 H (X = F, Cl, et Br). Nos résultats théoriques indiquent que, plus la masse du substituant X du substrat est élevée, plus l'énergie d'activation est élevée, et donc, plus la réaction S N 2 est lente, mais plus la réaction de déprotonation est rapide. Ces résultats ont été largement confirmés par des résultats publiés portant sur les indices de liaison, l'énergie de perturbation de second ordre E (2) , et les calculs de barrière énergétique d'activation. En outre, nous avons exploré les différences de réactivité découlant de l'effet des substituants en fonction de la relation entre la barrière énergétique et les charges transférées ou la longueur du lien partant dans les états de transition, respectivement, et particulièrement dans les états de transition des réactions S N 2. Les constantes de vitesse aux températures allant de 298 à 1000 K ont aussi été calculées pour les réactions S N 2 à l'étude, selon la théorie de l'état de transition. [Traduit par la Rédaction] Mots-clés : anion ClO − , effet des substituants, théories de la fonctionnelle de la densité.

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“…Among the methyl chloride series, the CH 3 ClῌF ῌ reaction shows a nonstatistical behavior such that the rate is independent of the reactant internal energy. 54) A direct mechanism without formation of a long-lived complex has been suggested from the observed deviation of reaction cross sections at high collision energies 62) and by ab initio direct dynamics calculations (collision energy not specified).…”

Section: Fundamental Aspects Of Gas Phase Ion Chemistry Studied Usingmentioning

confidence: 99%

Fundamental Aspects of Gas Phase Ion Chemistry Studied Using the Selected Ion Flow Tube Technique

Kato¹

2005

J. Mass Spectrom. Soc. Jpn.

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Gas phase ion chemistry using the selected ion flow tube (SIFT) technique is discussed with the focus on fundamental studies on ion structure, energetics, reactivity, and dynamics: Laser-induced fluorescence (LIF) kinetics/dynamics of N 2 ῍ (v) ions (vibrationally state-selected ion῎molecule reactions; energy transfer processes), mechanisms of prototypical organic ion reactions (S N 2 nucleophilic substitution and kinetic isotope e#ects; hydrogen/deuterium exchange; isotope e#ects in termolecular association), and ion῎molecule reactions with biological implications (S N 2 reactions at a nitrogen center; E CO 2 elimination reactions of alkyl hydroperoxides). Anion chemistry of small nitroalkanes is also presented. A powerful combination of SIFT and negative ion photoelectron spectroscopy is used to study thermochemistry and structure of energetic and exotic ions (alkyl peroxides; anionic derivatives of diazo and azole compounds, cyclooctatetraene, and cyclopentanone). Finally, some of the new directions in SIFT research are discussed, i.e., reactions of ions with polyatomic organic radicals, and chemical ionization mass spectrometry with new detection schemes.

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Dynamics of the Gas-Phase Reactions of Fluoride Ions with Chloromethane

Cited by 71 publications

References 59 publications

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Gas-phase reaction of ClO⁻with CH_nCl_4-_n(n= 0, 1, 2, 3) and CX₃H (X = F, Cl and Br): Substituent effect from a comparative study

Fundamental Aspects of Gas Phase Ion Chemistry Studied Using the Selected Ion Flow Tube Technique

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Dynamics of the Gas-Phase Reactions of Fluoride Ions with Chloromethane

Cited by 71 publications

References 59 publications

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Revealing a double-inversion mechanism for the F−+CH3Cl SN2 reaction

Gas-phase reaction of ClO−with CHnCl4-n(n= 0, 1, 2, 3) and CX3H (X = F, Cl and Br): Substituent effect from a comparative study

Fundamental Aspects of Gas Phase Ion Chemistry Studied Using the Selected Ion Flow Tube Technique

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Gas-phase reaction of ClO⁻with CH_nCl_4-_n(n= 0, 1, 2, 3) and CX₃H (X = F, Cl and Br): Substituent effect from a comparative study