| Electron-withdrawing Substituent |
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Information AboutElectron-withdrawing Substituent |
| CATEGORIES ABOUT POLAR EFFECT | |
| physical organic chemistry | |
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The Polar effect or '''electronic effect''' in Chemistry is the effect exerted by a Substituent on modifying Electrostatic Force s operating on a nearby Reaction center. The main contributors to the polar effect are the Inductive Effect , Mesomeric Effect and the through-space electronic Field Effect . An electron withdrawing group or '''EWG''' draws electrons away from a reaction center. When this center is an electron rich Carbanion or an Alkoxide anion the presence of the substituent has a stabilizing effect. Examples of electron withdrawing groups are:
An electron releasing group or '''ERG''' (otherwise called electron donating groups or EDG) releases electrons into a reaction center and as such stabilizes electron deficient Carbocation s. Examples of electron releasing groups are: The total substituent effect is the combination of the polar effect and the combined Steric Effect s. In Electrophilic Aromatic Substitution and Nucleophilic Aromatic Substitution substituents are divided into Activating Group s and Deactivating Group s where the direction of activation or deactivation is also taken into account. EXTERNAL LINKS |
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