Sodium naphthalene is an organic salt with the chemical formula . In the research laboratory, it is used as a reductant in the synthesis of organic, organometallic, and inorganic chemistry. It is usually generated in situ. When isolated, it invariably crystallizes as a solvate with ligands bound to .[1]
The alkali metal naphthalene salts are prepared by stirring the metal with naphthalene in an ethereal solvent, usually as tetrahydrofuran or dimethoxyethane. The resulting salt is dark green.[2] The anion is a radical, giving a strong EPR signal near g = 2.0. Its deep green color arises from absorptions centered at 463 and 735 nm.
Several solvates of sodium naphthalenide have been characterized by X-ray crystallography. The effects are subtle, the outer pair of CH−CH bonds contract by 3 pm and the other nine C−C bonds elongate by 2–3 pm. The net effect is that reduction weakens the bonding.[3] [4]
With a reduction potential near −2.5 V vs NHE, the naphthalene radical anion is a strong reducing agent.[1] It is capable of defluorinating PTFE and is commonly used for chemically etching PTFE to allow adhesion.
The anion is strongly basic, and a typical degradation pathway involves reaction with water and related protic sources such as alcohols. These reactions afford dihydronaphthalene:
Alkali metal salts of the naphthalene radical anion are used to prepare complexes of naphthalene.[5]
See main article: radical anion.