Acid-catalyzed aromatizations of arene oxides and arene hydrates: are arene oxides homoaromatic?

The measurement of the rates of acid-catalyzed dehydration of water adducts (hydrates) of benzene, naphthalene, anthracene and phenanthrene reveals that the mechanism of dehydration is different from that of simple alcohols which have a rate-determining deprotonation of the carbocation. This indicates the lower stability of an alkene than an arene product. The relative stabilities of carbocation intermediates and hydrate reactants are also revealed by their reactivity. Homoaromatic stabilization of the arene oxides is the cause for the reactivity.