CH1012
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ALKYNES
• Alkynes generally display very similar reactivity to alkenes with bromination, hydration & hydrohalogenation occurring.
A notable exception: terminal RCCH alkynes
• The H of terminal alkynes is weakly acidic pKa » 25 compared with alkenes pKa » 44.
• Treatment with a strong base gives an acetylide anion a very useful nucleophile in organic synthesis.
• The strong base here is sodium amide &
when R = H the product is sodium acetylide.
   S.I. sodium ethynide