Sec 1 Structure Physical Properties Unusual Stability -Hydrogenation of just one double bond in benzene is endothermic! Benzene is 150 kJ/mol (36 kcal/mol)more stable than might be expected for,“cyclohexatriene” --(-359 predicted) 151kJ (-240 predicted) resonance energy energy 8kJ resonance energy -240 kJ/mol -232 kJ/mol -208 kJ/mol -120 kJ/mol energy Sec 1 Structure & Physical Properties ❖Unusual Stability ◼Hydrogenation of just one double bond in benzene is endothermic! ◼Benzene is 150 kJ/mol (36 kcal/mol) more stable than might be expected for “cyclohexatriene