![]() OH is more activating according to the ortho/para/meta directing chart. Note: Keep in mind that electrophile is an electron deficient species, so generally the one which is most reactive towards an electrophilic attack will be electron rich. the most reactive with electrophiles in electrophilic aromatic substitution. Therefore, the correct order of reactivity towards electrophilic substitution is Phenol > benzene > chlorobenzene > benzoic acid. General order of reactivity towards electrophilic substitution reaction: Aniline > Phenol > Anisole > Acetanilide > Toluene > Chlorobenzene > Fluorobenzene > Benzoic acid > Benzaldehyde > Nitrobenzene. Strongly deactivating substituents: Benzene sulphonic acid, Nitrobenzene, Cyanobenzene. ![]() Moderately deactivating substituents: Benzaldehyde, Acetophenone, Methyl benzoate Weakly deactivating substituents: Fluorobenzene, Chlorobenzene, Bromobenzene, Iodo benzene. Weakly activating substituents: Alkylbenzene, vinylbenzene, diphenyl Electrophilic aromatic substitution reactions are the very important class of reactions that allow the introduction of substituents onto arenes. For now, let’s see how the activation and ortho, para regioselectivity works by the inductive and resonance effects. Moderately activating substituents are: Acetanilide The following table summarizes the activating and deactivating groups and their directing effect in electrophilic aromatic substitution reactions: You can check this post for more details about the activating and deactivating groups. strongly activating substituents are: Aniline, Phenol, and Anisole The reactivity of phenol is comparatively more because the methyl group present on the methoxy substituent makes the oxygen less donating in nature thus reducing the activation of the ring. Whereas, the deactivating group directs the reaction to the meta position.Įlectrophilic substitution reaction rate increases if benzene is attached to the electron withdrawing group but rate decreases if the benzene is attached to the electron donating group. The activating group directs the reaction to the ortho or para position. Electrophilic aromatic substitution reactions create a new substituent at the ortho or para position. When Friedel-crafts is performed on methoxybenzene (anisole), the following compounds are formed. Generally an activating group is simply any substituent that increases the reactivity of the organic compound while a deactivating group tends to decrease the reactivity of the organic compound. The para position For example, electrophilic aromatic substitution reactions include Friedel-crafts reactions. Hint: You should know that in an electrophilic aromatic substitution reaction, the existing substituent groups on the aromatic ring have the ability to influence the overall reaction rate.įirst let us understand what are activating and deactivating groups.
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