Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Activating group
Introduction
In organic chemistry, a functional group is called an activating group (or electron donating group) if a benzene molecule to which it is attached more readily participates in electrophilic substitution reactions. Benzene itself will normally undergo substitutions by electrophiles, but additional substituents can alter the reaction rate or products by electronically or sterically affecting the interaction of the two reactants.
Functional groups are typically divided into three levels of activating ability. Deactivating groups are assigned to similar groupings.
Strongly Activating Groups
Strongly Activating Groups
- –OH -O–
R = alkyl
Strongly activating substituents favor electrophilic substitution about the ortho and para positions.
This is illustrated by drawing the resonance structure’s of aniline: [2]
Moderately Activating Groups
Moderately Activating Groups
- -NHCOCH3 -NHCOR
- -OCH3 -OR
Weakly Activating Groups
Weakly Activating Groups
- -CH3 -C2H5 -R
- -C6H5
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]