How may Kekule-type resonance structures canbe drawn for cyclooctatetraene, `C_(8)H_(8)`?

Options

A. Two
B. Three
C. Zero
D. One

Answer

1

Explanation

Since these are equivalnet energy resonance forms likethose for benzene we predict it to be aromatic The `Delta_(h)H^(ɵ)` for hydrogenating cyclooctatetraene to cylclooctene is about 4 times the value for the addition of `H_(2)` to cyclooctene indicating that there is little or no `pi` electron delocalization (resonance). Otherwise,`Delta_(h)H^(ɵ)` for cyclooctatetraene would be lower, indicatinglowerenergy and greater stability. this implies that the ability to write equivalent contributing resonance structures is not always reliable for predicting the aromaticity of conjugated carbocyclic polyenes. Molecular orbital theory, including Huckel's rule, is the best method for predicting aromaticity.