Why is cyclohexa-1,3,5-triene no longer accepted for the structure of benzene where the molecular formula is C6H6? Which is more stable and why?

This question requires understanding of the structure of benzene and forces the student to be able to describe why cyclohexa-1,3,5-triene is unable to be used to describe the structure of benzene. As benzene has the molecular formula C6H6, you would assume its structure would be cyclohexa-1,3,5-triene as carbon forms 4 bonds. Cyclohexa-1,3,5-triene consists of alternating carbon-carbon double bonds which would be drawn in the lesson. However, the structure of benzene shows that all the bonds have the same length, and so cyclohexa-1,3,5-triene can't be used to describe this structure as it has both double and single bonds which vary in length. In benzene, each carbon is bonded to one hydrogen and two carbons which is odd as carbon forms 4 bonds, so the spare electron in the orbitals become delocalised, forming a ring of delocalised electrons above and below the planar structure which provides the extra stability for benzene, giving it -208kJmol-1 for the enthalpy of hydrogenation. In the exam, the enthalpy for cyclohex-1-ene is given which is -120kJmol-1, so to calculate the change of enthalpy for cyclohexa-1,3,5-triene you would multiply this value by 3 to represent the 3 carbon-carbon double bonds. The change in enthalpy between the two compounds is 152kJmol-1. Benzene is more stable as it is less exothermic than cyclohexa-1,3,5-triene so more energy is taken in compared to cyclohexa-1,3,5-triene.