Question

why cleavage of phenyl alkyl ether with hbr

Answer 1

Cleavage of phenyl alkyl ether with HBr always produces phenol and alkyl bromide because of the presence of double bond character between the carbon and oxygen in structure (II), (III) and (IV) as shown below. The oxygen attached to the benzene ring cannot be easily removed, so the product formed in the above said reaction is phenol and not bromobenzene.