New observations on the metalation of naphthalene and β-ethylnaphthalene by potassium

A stable dinegative ion can be formed when naphthalene is metalated by an excess of potassium in tetrahydrofuran at 25°C; this previously unreported species obtained only at naphthalene concentrations lower than 3 x 10-2 m l-1. In the case of β-ethylnaphthalene, the initial dianion is isomerized into a dihydronaphthalene monoanion carrying an extra-cyclic anion as a result of an intramolecular hydrogen transfer; this dianionic species can be formed at concentrations higher than 3 x 10-2 m l-1. © 1980.