Radical-anion intermediates. Part IV. Radical anions of some 9-substituted fluorenes

Abstract

A large number of 9-substituted fluorenes react with alkali metals at –70 °C to give radical anions. At higher temperatures these radical anions are unstable and decay to give the corresponding anions. When either lithium or potassium was the counterion the radical anion decay was found to be first order in all but one system. When sodium was the counterion the decay was complicated by an equilibrium between metallic sodium and the hydrocarbon on one hand and the radical anion on the other. However it was possible in two such systems to determine ΔH° and ΔS° for this equilibrium. A small number of the 9-substituted fluorenes studied reacted at –70 °C to give both e.s.r. and u.v./visible absorption spectra identical to that of the fluorene radical-anion.