sodamide

Sodamide, also called sodium amide, is an inorganic compound with the formula NaNH2. It is a white to grayish crystalline solid that is highly reactive toward water and air. In organic synthesis it serves as one of the strongest common bases and is typically used in liquid ammonia as a solvent, where it exists as the amide ion (NH2−) paired with Na+.

Preparation and structure: It is prepared by direct combination of sodium metal with ammonia: 2 Na + 2 NH3 → 2 NaNH2 + H2. In ammonia solution, NaNH2 dissociates to provide NH2−, a very strong base. The solid and solutions are moisture sensitive, hydrolyzing readily to give sodium hydroxide and ammonia.

Reactivity and uses: The primary utility of sodamide is its extreme basicity. It deprotonates weak C–H bonds, especially terminal alkynes (R–C≡CH) to form acetylide anions (R–C≡C− Na+), which serve as nucleophiles for subsequent alkylation or coupling reactions. It also promotes double dehydrohalogenation of vicinal dihalides to give alkynes. In ammonia, sodamide bases can generate carbanions that enable various carbon–carbon bond-forming transformations.

Safety and handling: NaNH2 is highly caustic and reacts vigorously with water and air. It is stored under strictly dry, inert conditions in sealed containers under inert gas or in an atmosphere of dry ammonia, and handled under a fume hood with appropriate protective equipment. Contact with moisture or CO2 can release ammonia gas and heat, and can cause severe chemical burns.