Organic Synthesis

A terminal alkyne can be turned into an acetylide anion when reacted with sodamide in NH₃. Acetylide anions are strong bases and strong nucleophiles. Therefore, they are able to displace halides and other leaving groups in substitution reactions. Because it's a strong anion, methyl and primary halides are most efficient for a this substitution reaction. The product formed is a substituted alkyne.

Secondary or tertiary halides will convert to an alkene via an E2 mechanism reforming the terminal alkyne.