Question

When 4-pentene-1-ol is treated with aqueous bromide, a cyclic bromosubstituted ether is formed rather than expected bromohydrine. Select the explanation that best account for the result.

• A. The ether is the result of a hydride shift in the initially formed carbocation.
• B. The ether is formed in the intramolecular nucleophilic attack on the initially formed bromonium ion.
• C. The reaction is initiated by the deprotonation of the ${}^{}-OH$ group.
• D. The initially formed bromonium ion undergoes an alkene shift to form new $C-O$ bond.

Answer 1

The correct option is B The ether is formed in the intramolecular nucleophilic attack on the initially formed bromonium ion.

The bromine atom attacks carbon carbon double bond to form cyclic bromonium ion. The oxygen atom of hydroxyl group attacks cyclic bromonium ion to form cyclic ether.