Page 176 - Pharm.Org.Chem-I 02-06-05-101

Category Type Example of Substituents
Ortho–Para Directors Strongly Activating —NH₂, —NHR, —NR₂, —OH,
Meta Directors —O⁻
Moderately Activating
—NHCOR, —OCOR, —OR

Weakly Activating —R (alkyl), —C₆H₅ (phenyl)
Weakly Deactivating
Moderately Deactivating —F, —Cl, —Br, —I
—C≡N, —SO₃H, —COOH, —
Strongly Deactivating COOR, —CHO, —COR
—NO₂, —NR₃⁺, —CF₃, —
CCl₃

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In summary, all the activating substituents and the weakly deactivating halogens
are ortho–para directors .
whereas all substituents more deactivating than the halogens are meta directors.

In other words, all substituents that donate electrons either by resonance or by
hyperconjugation are ortho–para directors,
whereas all substituents that cannot donate electrons are meta directors.

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