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相关概念视频

Nucleophilic Substitution Reactions02:34

Nucleophilic Substitution Reactions

Historical perspective
In 1896, the German chemist Paul Walden discovered that he could interconvert pure enantiomeric (+) and (-) malic acids through a series of reactions. This conversion suggested the involvement of optical inversion during the substitution reaction. Further, in 1930, Sir Christopher Ingold described for the first time two different forms of nucleophilic substitution reactions, which are known as SN1 (nucleophilic substitution unimolecular) and SN2 (nucleophilic substitution...
SN2 Reaction: Kinetics02:14

SN2 Reaction: Kinetics

Kinetic Studies and Significance
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a reaction.
Nucleophilic Aromatic Substitution: Elimination–Addition01:11

Nucleophilic Aromatic Substitution: Elimination–Addition

Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as high temperatures or strong bases. The mechanism of substitution under such conditions involves the highly unstable and reactive benzyne intermediate. Benzyne contains equivalent carbon centers at both ends of the triple bond, each of which is equally susceptible to nucleophilic attack. This 50–50 distribution of products is confirmed through isotopic...
Nucleophilic Aromatic Substitution: Addition–Elimination (SNAr)01:30

Nucleophilic Aromatic Substitution: Addition–Elimination (SNAr)

Nucleophilic substitution in aromatic compounds is feasible in substrates bearing strong electron-withdrawing substituents positioned ortho or para to the leaving group. The reaction proceeds via two steps: the addition of the nucleophile and the elimination of the leaving group.
The reaction begins with an attack of the nucleophile on the carbon that holds the leaving group. This results in the delocalization of the π electrons over the ring carbons. The resonance interaction between the...
SN1 Reaction: Stereochemistry02:15

SN1 Reaction: Stereochemistry

This lesson provides an in-depth discussion of the stereochemical outcomes in an SN1 reaction.
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...
Electrophilic Aromatic Substitution: Overview01:16

Electrophilic Aromatic Substitution: Overview

In an electrophilic aromatic substitution reaction, an electrophile substitutes for a hydrogen of an aromatic compound.

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相关实验视频

Updated: Jul 8, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
06:53

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−

Published on: July 27, 2018

图像核友取代动态的核友取代动态.

J Mikosch1, S Trippel, C Eichhorn

  • 1Physikalisches Institut, Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany.

Science (New York, N.Y.)
|January 12, 2008
PubMed
概括
此摘要是机器生成的。

这项研究揭示了离子 (Cl-) 如何通过核替代 (S(N) 2) 与甲基化物 (CH3I) 反应. 碰撞能量控制反应路径,从复杂介导转向直接散射,涉及独特的分子旋转动力学.

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Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo
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Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

Published on: September 26, 2016

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
10:54

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR

Published on: February 23, 2016

相关实验视频

Last Updated: Jul 8, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
06:53

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−

Published on: July 27, 2018

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo
08:01

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

Published on: September 26, 2016

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
10:54

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR

Published on: February 23, 2016

科学领域:

  • 化学动力学 化学动力学
  • 物理化学 物理化学
  • 分子反应机制分子反应机制

背景情况:

  • 阳离子-分子核替代 (S(N) 2) 反应由于复杂的潜在能量表面和量子状态合而表现出复杂的动态.
  • 了解这些动态对于预测化学反应性和设计新的合成途径至关重要.

研究的目的:

  • 阐明离子 (Cl-) 和化 (CH3I) 之间的S(N) 2反应的详细反应动态.
  • 研究碰撞能量对反应机制和产品散射的影响.

主要方法:

  • 利用交叉分子束成像来实验地探测Cl- + CH3I反应.
  • 进行了详细的化学动力学计算,以建模反应路径和能量转移.

主要成果:

  • 观察到,随着碰撞能量的增加,化离子 (I-) 的反应机制从复杂介导向直接反向散射的转变.
  • 确定了一种间接的"绕道"反应机制,涉及甲基组 (CH3) 的旋转.

结论:

  • 碰撞能量是决定Cl- + CH3I的S(N) 2反应机制的关键因素.
  • 这项研究揭示了分子旋转在控制反应路径和能量处置中的作用的新见解.