Describe why phenol reacts more readily with bromine than benzene does.

(labelled diagrams of both benzene and phenol would be used to show the overlapping p orbitals above and below the plane of the molecule, with phenol showing the partial delocalisation of the oxygen lone pairs into the pi bond ring structure)Benzene is bonded covalently by a delocalised ring system of pi bonds. Each carbon is bonded to 3 other atoms (2 carbons and a hydrogen atom) by sigma bonds, leaving 1 electron delocalised in a p orbital. These p orbitals overlap sideways above and below the plane of the molecule and spread over all 6 carbons in the ring, forming a pi bond structure with low electron density (as the 6 delocalised electrons are spread over 6 carbons). This low electron density means that benzene cannot induce a dipole or attract electrophiles as easily as phenol.Phenol contains an oxygen atom which contributes a lone pair that partially delocalises into the pi bond structure, increasing its electron density. This means that its electrons can repel electrons in the Br-Br bond in bromine to induce a dipole, and can attract the positive charge on the electrophile more readily.