Acetylene (${\mathrm{C}}_2{\mathrm{H}}_2$)

Acetylene, or ethyne, is the alkyne $\mathrm{HC}\equiv \mathrm{CH}$. Its carbon centers have approximately linear geometry, and the carbon-carbon triple bond contains one sigma and two pi bonding interactions.

Its terminal carbon-hydrogen bonds are more acidic than ordinary alkane carbon-hydrogen bonds. Deprotonation gives an acetylide nucleophile, connecting the molecule's bonding to carbon-carbon bond formation.