Deprotonating alkynes

Alkynes, with a sp orbital used in the C-H bond, are relatively acidic hydrocarbons. They can be deprotonated by organometallics, with the carbanion acting as a base.

This can also be done with other strong bases, such as sodium amide:

Like alkynyl lithiums, the sodium acetylide be used a nucleophillic carbanion. An example is the one-step conversion from estrone (a female sex hormone) to ethynyl estradiol (an ingredient in many contraceptive pills).