Why is benzene more stable than the theoretical model cyclohexa-1,3,5-triene?

In cyclohexa-1,3,5-triene the molecule has 3 single bonds and 3 double bonds where all the electrons are localised. As a result the energy needed to hydrogenate cyclohexa-1,3,5-triene is (3x -120kJ/mol) = -360kJ/mol.However, benzene is a planar, aromatic molecule so all of the pz orbitals overlap. The overlap of the pz orbitals form a ring of resonance and allows all 6 pz electrons to be delocalised across the ring. The delocalisation of the pi electrons contributes to the stabalisation energy of benzene. This extra energy from resonance means benzene has a lower hydrogenation energy of -208kJ/mol and is more stable than predicted.

AP
Answered by Afia P. Chemistry tutor

22609 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

How would you expect the H-NMR spectrum of ethanol to differ from the H-NMR spectrum of ethane?


Why do ionisation energies typically increase upon going across a period yet decrease upon going down a group?


How does radiocarbon dating work?


What are the shape of p orbitals?


We're here to help

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

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning