Bromination of phenol Mechanism: Steps and Conditions

Conditions

Bromine water, room temperature, no catalyst. Gives 2,4,6-tribromophenol, a white precipitate.

Red curly arrows show where each pair of electrons moves.

Step 1Electrons flow from the oxygen lone pair through the ring to attack Br₂ at the 4-position; bromide leaves.

Step 2Bromide removes the proton from the sp³ carbon and the ring becomes aromatic again.

Benzene keeps its stable aromatic ring by substituting rather than adding. An electrophile attacks, then a proton is lost to restore aromaticity.

Practise this mechanismDraw the curly arrows yourself and Bondline checks each one. Or add it to your notes and watch it in 3D.