Monosodium acetylide

Monosodium acetylide is an organosodium compound with the formula NaC\tCH. It is a sodium salt of acetylene, consisting of sodium cations Na+ and hydrogen acetylide anions −C\tCH. It is a derived from acetylene by deprotonation using a sodium base, typically sodium amide.
 * HC\tCH + NaNH2 → NaC\tCH + NH3

This compound, a white solid, has been characterized by neutron diffraction, which revealed an Na-C bond and a C\tC bond of 127 pm, which is longer than the C\tC bond length in acetylene itself (120.4 pm). As a reagent, monosodium acetylide has been largely displaced by monolithium acetylide, which can be prepared more easily.

Monosodium acetylide hydrolizes in contact with water, producing sodium hydroxide and acetylene.
 * NaC\tCH + H2O → HC\tCH + NaOH