Effect of higher order solvation and temperature on SN2 and E2 reactivity

Eyet, Nicole; Melko, Joshua J.; Ard, Shaun G.; Viggiano, Albert A.

doi:10.1016/j.ijms.2014.07.011

Cited by 18 publications

(52 citation statements)

References 32 publications

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“…Detailed studies of the F – (CH 3 OH) 0,1 + CH 3 CH 2 Br dynamics on the full dimensional M06/ECP/d PES employed a direct dynamics approach, for which the gradient required for the simulations is achieved directly from an electronic structure theory . To compare with experiments, the simulations were performed at an initial collision energy ( E coll ) of 0.04 eV, the average value for a 300 K collision, with the reactants’ vibrational and rotational energies sampled from their 300 K Boltzmann distributions. Quasiclassical sampling, , which includes zero-point energy (ZPE) of each vibrational mode, was used to determine initial coordinates and momenta for the trajectories.…”

Section: Methodsmentioning

confidence: 99%

How a Solvent Molecule Affects Competing Elimination and Substitution Dynamics. Insight into Mechanism Evolution with Increased Solvation

et al. 2018

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Competiting S2 substitution and E2 elimination reactions are of central importance in preparative organic synthesis. Here, we unravel how individual solvent molecules may affect underlying S2/E2 atomistic dynamics, which remains largely unclear with respective to their effects on reactivity. Results are presented for a prototype microsolvated case of fluoride anion reacting with ethyl bromide. Reaction dynamics simulations reproduce experimental findings at near thermal energies and show that the E2 mechanism dominates over S2 for solvent-free reaction. This is energetically quite unexpected and results from dynamical effects. Adding one solvating methanol molecule introduces strikingly distinct dynamical behaviors that largely promote the S2 reaction, a feature which attributes to a differential solute-solvent interaction at the central barrier that more strongly stabilizes the transition state for substitution. Upon further solvation, this enhanced stabilization of the S2 mechanism becomes more pronounced, concomitant with drastic suppression of the E2 route. This work highlights the interplay between energetics and dynamics in determining mechanistic selectivity and provides insight into the impact of solvent molecules on a general transition from elimination to substitution for chemical reactions proceeding from gas- to solution-phase environments.

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Section: Methodsmentioning

confidence: 99%

How a Solvent Molecule Affects Competing Elimination and Substitution Dynamics. Insight into Mechanism Evolution with Increased Solvation

et al. 2018

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“…All procedures were in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals (Institute of Laboratory Animal Resources, 1996). The alkaloids, including scholaricine (5, Sch), 19-epi-scholaricine (6, Epi), vallesamine (13,Val) and picrinine (27, Pic), were, respectively, suspended in 0.3% sodium carboxy-methyl cellulose and were administrated to rats (n = 4) by gavage at a dose of 50 mg/kg body weight. AAS was fed to rats (n = 4) at 150 mg/kg (high dose) and 10 mg/kg (clinical dose, equivalent to 120 mg/day for a 70-kg human), respectively.…”

Section: Animals and Drug Administrationmentioning

confidence: 99%

“…We consider the loss of H 2 O was attributed to the condensation reaction between 19-OH and 20-H. Since that trans elimination is superior to cis [12,13], Epi (R) eliminated the water molecule more easily than Sch (S).…”

Section: Scholaricine-type Alkaloidsmentioning

confidence: 99%

Characterization of chemical constituents and rats metabolites of an alkaloidal extract of Alstonia scholaris leaves by liquid chromatography coupled with mass spectrometry

Cao

Shen

Wang

et al. 2016

Journal of Chromatography B

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“…Studies under single-collision conditions, which allow focusing on the intrinsic dynamics while excluding solvation effects, are complicated by the fact that both reactions usually form the same product ion and can not be distinguished by standard mass spectrometry. Several elaborate methods have therefore been employed to distinguish between the two reactions in the gas phase 13 , 14 , 17 , 19 . Interestingly, S N 2 leads to the thermodynamically more stable product while E2 features the lower transition state barrier, i. e. E2 forms the kinetically preferred product.…”

mentioning

confidence: 99%

Atomistic dynamics of elimination and nucleophilic substitution disentangled for the F− + CH3CH2Cl reaction

et al. 2021

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Chemical reaction dynamics are studied to follow and understand the concerted motion of several atoms while they rearrange from reactants to products. With the number of atoms growing, the number of pathways, transition states, and product channels also increases and rapidly presents a challenge to experiment and theory. Here, we disentangle the competition between bimolecular nucleophilic substitution (S N 2) and base-induced elimination (E2) in the polyatomic reaction F - + CH 3 CH 2 Cl. We find quantitative agreement for the energy- and angle-differential reactive scattering cross sections between ion imaging experiments and quasi-classical trajectory simulations on a 21-dimensional potential energy hypersurface. The anti-E2 pathway is most important, but the S N 2 pathway becomes more relevant as the collision energy is increased. In both cases the reaction is dominated by direct dynamics. Our study presents atomic level dynamics of a major benchmark reaction in physical organic chemistry, thereby pushing the number of atoms for detailed reaction dynamics studies to a size that allows applications in many areas of complex chemical networks and environments.

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Effect of higher order solvation and temperature on SN2 and E2 reactivity

Cited by 18 publications

References 32 publications

How a Solvent Molecule Affects Competing Elimination and Substitution Dynamics. Insight into Mechanism Evolution with Increased Solvation

How a Solvent Molecule Affects Competing Elimination and Substitution Dynamics. Insight into Mechanism Evolution with Increased Solvation

Characterization of chemical constituents and rats metabolites of an alkaloidal extract of Alstonia scholaris leaves by liquid chromatography coupled with mass spectrometry

Atomistic dynamics of elimination and nucleophilic substitution disentangled for the F− + CH3CH2Cl reaction

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