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What is formed when CH3MgX reacts with CH3C≡CH?

1. CH3–CH=CH2
2. CH3C≡C–CH3
3. CH3–C(H)=C(H)–CH3
4. CH4

Correct answer: CH4

Solution

Propyne has an acidic terminal C-H, so CH3MgX acts as a base: CH3C#CH + CH3MgX -> CH3C#C-MgX + CH4. The evolved product is methane, not 2-butyne.

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