salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quanti ...
with the chemical formula Na+. In the research laboratory, it is used as a reductant in the synthesis of organic, organometallic
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and ...
, and inorganic chemistry. It is usually generated in situ. When isolated, it invariably crystallizes as a solvate with ligands bound to Na+.
Preparation and properties
The alkali metal naphthalene salts are prepared by stirring the metal with naphthalene
Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromat ...
in an ether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again b ...
eal solvent, usually as tetrahydrofuran
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...
or dimethoxyethane
Dimethoxyethane, also known as glyme, monoglyme, dimethyl glycol, ethylene glycol dimethyl ether, dimethyl cellosolve, and DME, is a colorless, aprotic, and liquid ether that is used as a solvent, especially in batteries. Dimethoxyethane is misc ...
. The resulting salt is dark green. 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
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angle ...
. 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.
Reactions
;Redox With a reduction potential near −2.5 V vs NHE, the naphthalene radical anion is a strong reducing agent. ;Protonation 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: :2 NaC10H8 + 2 H2O → C10H10 + C10H8 + 2 NaOH ;As a ligand Alkali metal salts of the naphthalene radical anion are used to prepare complexes of naphthalene.Related reagents
References
{{sodium compounds One-electron reducing agents Organosodium compounds Free radicals Naphthalenes