Explain how an –OH group attached to a carbon in the benzene ring activates benzene towards electrophilic substitution.
Solution
Resonance donation: the oxygen lone pair delocalises into the ring, the canonical structures placing negative charge on the ortho and para carbons.
The ring, now electron-rich, attracts electrophiles far more strongly than benzene — phenol brominates even with bromine water, nitrates with dilute HNO — and substitution lands at the o/p positions.
The ring, now electron-rich, attracts electrophiles far more strongly than benzene — phenol brominates even with bromine water, nitrates with dilute HNO — and substitution lands at the o/p positions.
CBSE Class 12 Board · 2005 · All India · Subjective