JEE MainChemistryAlcohols Phenols and Ethers
Phenol reacts with Br ₂ in CS ₂ at 273 K to give a major product P. P reacts with aqueous NaOH followed by CH ₃ I to give Q. Q is heated with concentrated HI to give an aromatic product R and an aliphatic product S. Identify the structures of P, Q, and R.
Options
- AP is 2,4,6-tribromophenol; Q is 2,4,6-tribromoanisole; R is 2,4,6-tribromophenol
- BP is 4-bromophenol; Q is 4-bromoanisole; R is 4-bromophenol
- CP is 4-bromophenol; Q is 4-bromoanisole; R is 1-bromo-4-iodobenzene
- DP is 4-bromophenol; Q is 4-bromoanisole; R is 4-iodophenol
Correct answer
B. P is 4-bromophenol; Q is 4-bromoanisole; R is 4-bromophenol
Step-by-step solution
Phenol reacts with Br ₂ in a non-polar solvent ( CS ₂ ) at low temperature to undergo monohalogenation. The major product P is 4-bromophenol. 4-bromophenol reacts with aqueous NaOH to form sodium 4-bromophenoxide, which then undergoes Williamson ether synthesis with CH ₃ I to form 4-bromoanisole (Q). When 4-bromoanisole is heated with concentrated HI , the ether linkage is cleaved. Since the aryl-oxygen bond has partial double bond character due to resonance and is stronger, the cleavage occurs at the alkyl-oxygen