Reaction Type: Elimination (E2)
- The two p bonds of an alkyne can be formed using two consecutive elimination reactions.
- The leaving groups are usually halides (esp. Br or Cl)
- Reagent : usually NaNH2 (a strong base, pKa = 35)
- Either geminal (e.g. 1,1-) or vicinal (e.g. 1,2-) dihalides can be used.
- Since 1,2-dihalides can be prepared by addition of X2 to an alkene, an alkene can be converted into an alkyne in two steps.
- These reactions are typically E2 reactions and occur via an alkenyl halide.
- The strong base is needed in order to cause elimination of the alkenyl halide.