Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

E2 Reaction: Kinetics and Mechanism

E2 Reaction: Kinetics and Mechanism

SN2 substitutions and E2 eliminations of alkyl halides proceed via a concerted pathway. While the nucleophile attacks the alpha carbon in SN2 reactions, it functions as a strong base and abstracts a beta hydrogen in the E2 mechanism. The rate-limiting transition state in E2 elimination reactions is characterized by partially broken carbon–hydrogen and carbon–halogen bonds and a partially formed pi bond between the alpha and beta carbons. The beta hydrogen and halide are eliminated...

E1 Reaction: Kinetics and Mechanism

E1 Reaction: Kinetics and Mechanism

Here, in contrast to the E2 reaction mechanism, we delve into the aspects of the E1 reaction mechanism, which has two steps: rate-limiting loss of the leaving group and abstraction of the beta hydrogen by a weak base. Typically, the experimental proof for the E1 mechanism is via kinetic studies or isotope studies. While the former demonstrates the first-order kinetics—the dependence of the reaction solely on substrate concentration—the latter proves the abstraction of hydrogen only...

SN2 Reaction: Transition State

S_N2 Reaction: Transition State

An SN2 reaction of an alkyl halide is a single-step process in which bond formation between the nucleophile and the substrate and bond breaking between the substrate and the halide occurs simultaneously through a transition state without forming an intermediate.
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...

SN1 Reaction: Mechanism

S_N1 Reaction: Mechanism

Kinetic studies of ionization of a tertiary halide in a protic solvent suggest that only the substrate participates in the rate-determining step (slow step). The nucleophile is involved only after the slowest step. The SN1 reaction takes place in a multiple-step mechanism.
Firstly, the haloalkane ionizes to generate a carbocation intermediate and a halide ion. This heterolytic cleavage is highly endothermic with large activation energy. The ionization of the substrate, facilitated by a...

SN2 Reaction: Mechanism

S_N2 Reaction: Mechanism

The kinetic studies of SN2 reactions suggest an essential feature of its mechanism: it is a single-step process without intermediates. Here, both the nucleophile and the substrate participate in the rate-determining step.
The presence of the more electronegative halogen in the substrate creates a polarized carbon-halide bond. The halide pulls the electron cloud generating an electrophilic center at the carbon atom. Thus, the carbon atom carries a partial positive charge while the halide has a...

Predicting Products: SN1 vs. SN2

Predicting Products: S_N1 vs. S_N2

Nucleophilic substitution reactions of alkyl halides can proceed via an SN1 or an SN2 mechanism. While in SN2 reactions, the nucleophile attacks the substrate simultaneously as the leaving group departs, in SN1 reactions, the substrate first dissociates to give the carbocation intermediate. Various factors such as the structure of the substrate, the strength of the nucleophile, and the nature of the solvent promote one mechanism over the other.
With increased substitution on the alkyl halide,...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Peri-Implant Tissue Stability Following Guided Bone Regeneration With Bioceramic: A Multicenter One-Year Cohort Study.

Clinical implant dentistry and related research·2026

Same author

Soil nutrient stability outperforms microbial abundance stability as an early-warning indicator in a Tibetan alpine meadow under seasonal asymmetric warming.

Journal of environmental management·2026

Same author

Correction: The Dynamics of Soil Organic Carbon in Alpine Grasslands Affected by Livestock Grazing Intensity.

Environmental management·2026

Same author

Effects of a 12-Year Nitrogen Addition Experiment on Protist Communities in a Boreal Forest, Heilongjiang Province, China.

Animals : an open access journal from MDPI·2026

Same author

Fresh aboveground net primary productivity of Tibetan grasslands: Responses of different plant functional groups to climate change and human activities and implications for ecosystem management.

PloS one·2026

Same author

The Dynamics of Soil Organic Carbon in Alpine Grasslands Affected by Livestock Grazing Intensity.

Environmental management·2026

Same journal

Precise Synthesis of Star-Shaped Redox-Responsive Segmented Polyurethanes with Controlled Arm Sequences for Drug Delivery.

Precision chemistry·2026

Same journal

Paradoxical Suppression of Exciton Diffusion by Long-Range Interactions: A Large-Scale Nonadiabatic Dynamics Study.

Precision chemistry·2026

Same journal

Chemically Recyclable Thermoplastic Elastomers: Preparation, Properties, and On-Demand Depolymerization.

Precision chemistry·2026

Same journal

Potent and Receptor-Selective Germination Inhibitor for <i>Striga hermonthica</i>.

Precision chemistry·2026

Same journal

Flavor-Enhancing Pentapeptide AGPNY from Tomato Proteins: Potential Dual-Targeting of Umami Receptors T1R1/T1R3 and GRM1 through Computational-Experimental Synergy.

Precision chemistry·2026

Same journal

Multivariate Synergy and Two-Dimensional Confinement: Research Progress and Opportunities of Two-Dimensional High-Entropy Alloys.

Precision chemistry·2026

See all related articles

Search research articles

Related Experiment Video

Updated: Sep 9, 2025

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Published on: March 24, 2018

E2/S_N2 Selectivity Driven by Reaction Dynamics. Insight into Halogen Bonding.

Siwei Zhao¹, Hongyi Wang¹, Gang Fu¹

¹MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150001, People's Republic of China.

Precision Chemistry

|August 29, 2025

Summary

This summary is machine-generated.

The leaving group significantly influences the dynamics of competing E2 elimination and SN2 substitution reactions. Halogen bonding alters interaction potentials, causing mechanistic shifts and unique dynamic features in chemical synthesis.

Keywords:

Atomistic Dynamics E2/SN2 Competition Halogen Bond Leaving Group Reaction Mechanisms

More Related Videos

The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique

The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique

Published on: November 28, 2016

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Published on: August 18, 2017

Related Experiment Videos

Last Updated: Sep 9, 2025

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Published on: March 24, 2018

The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique

The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique

Published on: November 28, 2016

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Published on: August 18, 2017

Area of Science:

Physical Chemistry
Chemical Dynamics
Organic Synthesis

Background:

The competition between E2 elimination and SN2 substitution is fundamental in organic synthesis.
The influence of leaving groups on reaction dynamics, beyond mere reactivity, is not well understood.

Purpose of the Study:

To investigate how the leaving group's nature affects the intrinsic dynamics of E2 elimination versus SN2 substitution.
To elucidate the mechanistic pathways and identify dynamic fingerprints of these competing reactions.

Main Methods:

Utilized chemical dynamics simulations to model the reaction of fluoride anion with ethyl chloride and ethyl iodide.
Compared simulation results with experimental scattering signatures to validate the models.
Analyzed interaction potentials and atomistic behaviors to understand the role of leaving groups.

Main Results:

Identified direct stripping/rebound mechanisms as characteristic of E2/SN2 reactions, consistent with experimental data.
Observed distinct dynamic features between chloride and iodide leaving groups, despite similar structures and energetics.
Discovered that halogen-bonding attraction critically modifies the interaction potential, inducing mechanistic shifts.

Conclusions:

Leaving groups exert significant dynamical effects on base-induced elimination and nucleophilic substitution reactions.
Understanding these dynamical effects provides crucial insights into reaction selectivity in complex chemical systems.