Na2C2

Na2C2, commonly called disodium acetylide, is an inorganic compound consisting of sodium cations and the ethynide (C2)2− anion. It belongs to the family of alkali metal acetylides and is typically described as a moisture- and air-sensitive ionic solid.

In the solid, the C2 2− units are paired with Na+ ions, forming an ionic lattice. The compound is highly reactive and is typically stored and handled under inert atmosphere. It acts as a strong base and a source of acetylide ions for further chemical transformations.

Preparation of disodium acetylide is usually accomplished by direct reaction of sodium metal with acetylene gas in an inert solvent such as liquid ammonia, under appropriate temperature control. Other routes involve formation or reduction of acetylide-containing precursors followed by purification.

Reactivity: Na2C2 reacts vigorously with water to give sodium hydroxide and acetylene: Na2C2 + 2 H2O → 2 NaOH + HC≡CH. It also reacts with acids to liberate acetylene gas. As a reducing agent, it can participate in various organic and inorganic transformations, typically under strictly anhydrous conditions.

Applications and safety: As a source of acetylide ions, Na2C2 is used in synthesis to generate alkynyl compounds and propargyl derivatives, often via hydrolysis or reaction with carbonyl compounds followed by workup. Handling requires dry, inert conditions due to its reactivity with moisture and air; contact with water or moisture can release acetylene gas and pose fire or explosion hazards. Related acetylides include Li2C2 and K2C2.

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