Benzene vs Kekule

Bonding

• three covalent bonds - C—H and two C—C

• spare electrons in p orbital overlap

• delocalised electrons

Shape

• planar molecule

• 6 ring carbon 120° bond angle

• C—C bonds same length

Hydrogenation

• expected enthalpy of hydrogenation of benzene 360kJmol^-1

• real enthalpy is 152kJmol^-1 lower

• benzene is much more stable

cyclohexa-1,3,diene - lower enthalpy than