Question #d16ba

1 Answer
Ernest Z.
Oct 24, 2014

Yes, I can think of two methods for preparing ketones from alkynes.

Acid-Catalyzed Hydration

The Markovnikov addition of water to an alkyne, catalyzed by sulfuric acid and Hg²⁺, forms an enol. The enol is unstable and tautomerizes to form a ketone.

chemwiki.ucdavis.edu

Hydroboration-Oxidation of Symmetrical Alkynes

This is a three-step reaction sequence.

1. Addition of boron hydride forms a trialkenylborane.

3RC≡CR + BH₃ → (RCH=CR)₃B

2. Oxidation with basic H₂O₂ forms an enol

(RCH=CR)₃B → 3RCH= CR(OH)

3. The enol tautomerizes to the more stable ketone

RCH= CR(OH) → RCH₂COR

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