Directing effects in electrophilic aromatic substitution (ortho-para vs meta) (Activating and weakly deactivating ortho-para directors steer next E+ to ortho/para)
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Activating and weakly deactivating ortho-para directors steer next E+ to ortho/para; strong deactivators (meta directors) steer to meta.
What each symbol means
| Symbol | What it stands for |
|---|---|
| Inductive | Withdrawal/donation of σ electrons |
| Resonance | Donation/withdrawal from π system — dominates for many substituents |
When to use this
Electrophilic aromatic substitution on monosubstituted benzenes. Halogens are deactivating but ortho-para directing (lone pair resonance donation).