Benzene consists of a ring of 6 carbon atoms bonded to each other by sigma bonds from the overlap of s orbitals.p orbitals above and below the ring overlap to form a delocalised pi system with rings of electron density above and below the ring - this means all the bonds are the same length and have the same reactivity, compared with the Kekule structure where the single and double bonds have different lengths and the double bonds are more reactive.Benzene is less reactive with electrophiles than cyclohexene because the delocalised pi system has a lower electron density than the localised pi bond in the C=C double bond. This also means benzene cannot polarise bonds to generate nucleophiles, so reactions may need to take place in the presence of a halogen carrier.