Alkyl halides treated with acetylide anions will undergo SN2 reactions to give alkynes.
Acetylide addition (RC≡C‾) Explained:
Acetylide anions are the conjugate base of acetylenes (alkynes), and this is a commercial way to obtained alkynes. This process is only efficient with primary alkyl halides, possibly secondary which can undergo E2 mechanism because of steric hindrance of the leaving group.