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

21958 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

What is the difference between E-Z isomers and optical isomers?


What is the ideal gas equation?


Explain why the first ionisation energy of sulfur is different from that of phosphorus.


What is the difference between Sn1 and Sn2 reactions?


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