Metal Chloride Reductions with Aromatic Radical Anions. The Magnesium Chloride Catalysed Cleavage of Tetrahydrofuran by Sodium Naphthalene Radical Anion

Abstract

Activated metals for organic synthesis are often prepared by reduction of metal salts using alkali metal aromatic radical anions. The reduction of magnesium chloride has been examined by NMR. Whereas the expected reduction to the metal occurred with lithium or potassium naphthalene radical anion, under certain conditions, with sodium naphthalene radical anion, no metallic magnesium was precipitated and dark red solutions were obtained. It was also found that solutions of sodium naphthalene radical anion in tetrahydrofuran, in the presence of a catalytic amount of magnesium chloride, quickly became diamagnetic. A mechanism involving bimetallic species is postulated to explain the results.