Bonding (aromatic chemistry)

The nature of the bonding in a benzene ring, limited to planar structure and bond length intermediate between single and double.

Delocalisation of p electrons makes benzene more stable than the theoretical molecule cyclohexa-1,3,5-triene.

Students should be able to:

• use thermochemical evidence from enthalpies of hydrogenation to account for this extra stability

• explain why electrophilic substitution reactions occur in preference to addition reactions (energetic preference to maintain benzene electron delocalisation ring).