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