naphthalenide

Naphthalenide refers to the radical anion of naphthalene produced by the one-electron reduction of naphthalene. In practice it is encountered as a salt of the naphthalenide anion, most commonly potassium naphthalenide, represented as K+[C10H8]−. The species serves as a strong, single-electron reducing agent in organic synthesis and as a source of aryl anions for further transformations.

Preparation typically involves dissolving naphthalene in liquid ammonia (or in an ether solvent such as THF) under inert conditions and adding an alkali metal, such as potassium or sodium. The process generates a deep blue to green solution corresponding to the naphthalenide salt. Preparation and use are usually conducted under strictly anhydrous, air-free conditions due to the reagent’s extreme reactivity.

Properties and reactivity: Naphthalenide is a highly reactive, one-electron donor. It reduces substrates via single-electron transfer, forming transient radical or anion intermediates that can subsequently undergo further reactions. The naphthalenide system is typically most effective at low temperatures and in aprotic solvents. It is sensitive to air and moisture, and the corresponding reducing solution must be handled under inert atmosphere.

Applications: In organic synthesis, naphthalenide and its salts are used to effect reductive transformations that are difficult with milder reagents, including reductions of various halides and other electrophiles, and to generate aryl nucleophiles for subsequent trapping or coupling steps. The chemistry overlaps with solvated-electron methods and other arene-based reductants; it is often employed in laboratory-scale, specialized reductive protocols.

Safety and handling: Naphthalenide salts are extremely reactive and should be prepared and used under strictly anhydrous, inert conditions. They can react violently with water or oxygen-containing substances and must be handled with appropriate protective equipment and in well-ventilated, controlled environments.