alkyne hydration

Question

Hydration of 2-butyne (Hg2+, H2SO4) gives major product:

RankGuru · Accepted Answer

1. **Reaction Setup**: Alkynes add water in the presence of acid and $Hg^{2+}$ catalyst (Kucherov Reaction).
2. **Enol Intermediate**: Water adds across the triple bond to form a vinyl alcohol (enol): $CH_3-C(OH)=CH-CH_3$.
3. **Tautomerism**: Enols are highly unstable and undergo Keto-Enol tautomerization rapidly. The hydrogen from Oxygen moves to the $\alpha$-carbon, and the $C-O$ single bond becomes a $C=O$ double bond.
4. **Final Product**: Tautomerization of the but-2-en-2-ol enol yields **Butan-2-one (Ethyl methyl ketone)**.
5. **Note**: Hydration of Ethyne gives Ethanal, but hydration of all higher alkynes gives ketones.

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alkyne hydration

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