Why is phenol more reactive than benzene?

Phenol (which is a benzene ring with one substituted carbon with a hydroxyl or alcohol group) does not require a halogen carrier to be halogenated whereas benzene itself cannot react with a halogen alone. 

What's the reason for this difference in reactvity between benzene and phenol? Let's take the bromination of phenol and benzene as examples and have a look at the electronic structure of both reactants. 

The electonic structure of benzene consists of delocalised pi-electrons above and below the ring of 6 carbon atoms with the electron density is shared throughout the ring.

Phenol has an OH group bonded to one of the carbons and this oxygen has two lone pairs in p-orbitals. Now these electrons can overlap with the electrons in the benzene ring and if we look at the molecule as a whole, the oxygen shares these electrons with the rest of the system and so, increases the electron density. This means that there is enough electron density in phenol to induce a dipole in a Br2 molecule, making it an electrophile that can then be attacked by the nucleophilic phenol. 

Benzene on the otherhand does not have sufficient electron density to induce this dipole so a strong enough electrophile must be produced using a halogen carrier like FeBrif benzene is to react at all. 

TN
Answered by Thomas N. Chemistry tutor

37203 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

The ratio between the molar mass of an alkene(A) and an alkyne(B) with the same number of carbon atoms is 1.05. Find the molecular formulas of the two hydrocarbons then write the reaction for how we can obtain the alkene A from the alkyne B.


State and explain the effect of the following on the rate of a reaction: a) increasing temp b) increasing pressure c) increasing concentration of ONE reactant d) adding a catalyst. In each case state what will happen to the rate constant, k.


Construct expressions for pH, Kw and Gibbs Free energy


What is Le Châtelier's principle?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences