Electrophilic substitution in phenols
Alcohols, Phenols and Ethers · Chemistry
Study notes
Why does phenol give tribromination with Br₂ water but anisole needs Br₂/FeBr₃? Step 1: –OH (+M) strongly activates the ring — even weak Br₂ (water) attacks. Step 2: All o/p positions react → 2,4,6-tribromophenol (white ppt). Step 3: Anisole's –OCH₃ is less activating (+M weaker, no H-bonding); needs Lewis acid. Step 4: Activation level decides reagent strength — phenol is hyper-reactive!