Halogen Effects in Aromatic Substitution

Halogens affect aromatic substitution by changing both the reactivity and the position of incoming electrophiles. As ring substituents, they are more electronegative than carbon. This lets them pull electrons away from the ring through the inductive effect, which deactivates the aromatic ring toward electrophilic substitutio...

Halogens are ortho–para directors. However, they deactivate the aromatic ring towards electrophilic substitutions.

This unusual behavior results from the interplay of their electron-withdrawing inductive effect and electron-donating resonance effect.

Halogens are more electronegative than carbon. When present as s...