Resonance Energy of an Arene Hydrocarbon from Heat of Combustion Measurements

A simple experimental method for determination of the resonance energy by measuring the energies of combustion for two isomeric compounds, aromatic 1- tert -butyl-3,5-dimethylbenzene and nonaromatic trans, trans, cis -1,5,9-cyclododecatriene is proposed. Both compounds not only have the same molecular formula, but also contain the same number of sp 2 and sp 3 carbon atoms. After converting the obtained values into the gas phase heats of combustion and subtracting one value from another, the resulting mean resonance energy of 184 kJ/mol was obtained. The proposed method can be offered as an experiment for an undergraduate physical chemistry lab curriculum.