吸电子基又叫electron withdrawing group（EWG） 是一个通过改变电子密度影响化合物反应活性的重要因素。 可以简单以两种方式来 判断一个基团是EDG还是EWG。

2024年7月12日 · 另外，根据与芳环作用的电子效应和共轭效应，又可以分为EDG（electron donating group）即供电子基团和EWG（electron withdrawing group）即拉电子或吸电子基团。 一般情况下，含有EDG的芳环，在邻对位发生亲电反应；而含有EWG的芳环，在间位发生亲电反应。

An electron donating group (EDG) or electron releasing group (ERG, Z in structural formulas) is an atom or functional group that donates some of its electron density into a conjugated π system via resonance (mesomerism) or inductive effects (or induction)—called +M or +I effects, respectively—thus making the π system more nucleophilic.

An electron-withdrawing group (EWG) is a group or atom that has the ability to draw electron density toward itself and away from other adjacent atoms. [1] This electron density transfer is often achieved by resonance or inductive effects.

2024年3月18日 · 供电子基又叫electron donating group（EDG）-表现电负性； 吸电子基又叫electron withdrawing group（EWG）-表现正电性；是一个通过改变电子密度影响化合物反应活性的重要因素。 富电子环在环中包含电子贡献官能…

EDG can be recognised by lone pairs on the atom adjacent to the π system, eg: -OCH 3; except-R, -Ar or -vinyl (hyperconjugation, π electrons) EWG = electron withdrawing group; EWG can be recognised either by the atom adjacent to the π system having several bonds to more electronegative atoms, or,

2023年4月5日 · What is the difference between EDG and EWG? The main difference between EDG and EWG is their effect on the electron density of a molecule. EDGs increase electron density in the molecule, while EWGs decrease electron density.

供电子基团（EDG）是指具有给予电子的能力，可以通过共轭作用或原子的电负性向分子提供电子密度的基团。 它们通常由硫、氮、磷、碳等元素组成，可以增加分子的电子密度，使分子表现出较强的亲核性。 常见的供电子基团包括氨基、羟基、甲基等。 根据吸电子基团与供电子基团的不同特性，我们可以根据需求选择合适的基团进行修饰。 如果想增加分子的亲电性，可以引入吸电子基团，如羰基、酮基等。 相反，如果需要增加分子的亲核性，可以引入供电子基团，如氨基、 …

The reactivity of aromatic pi bonds in S E Ar reactions is very sensitive to the presence of electron-donating groups (EDG) and electron-withdrawing groups (EWG) on the aromatic ring. This is due to the carbocation nature of the intermediate, which is stabilized by electron-donating groups and destabilized by electron-withdrawing groups.

What is the Difference Between EDG and EWG? EDG stands for electron donating groups while EWG stands for electron withdrawing groups. Both these are “electrophilic aromatic directing groups”. As a key difference between EDG and EWG, we can say that the EDG can increase the electron density of a conjugated pi system whereas the EWG decreases ...