The kinetics of the acid-catalyzed ring opening of naphthalene 1, 2-oxide (5) in highly aqueous media to give naphthols has been measured by heat-flow microcalorimetry. The reaction enthalpy of this aromatization reaction was measured as Δ H=-51.3±1.7 kcal mol-1. The unexpectedly low reactivity of naphthalene oxide is suggested to be due to an unusually large thermodynamic stability. A crude estimate of the stabilization effect,~ 1 kcal mol-1 ( ...