Question:
Propyne on reaction with water in presence of \(40\%\) sulphuric acid and \(1\%\) mercuric sulphate forms
Propyne on reaction with water in presence of \(40\%\) sulphuric acid and \(1\%\) mercuric sulphate forms
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Alkynes hydrate by Kucherov reaction to ketones, following Markovnikov.
Updated On: Oct 1, 2026
- Propan-1-ol
- Propan-2-ol
- Propanone
- Propanal
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
Addition of water to an alkyne in dilute \(\text{H}_2\text{SO}_4\) with \(\text{HgSO}_4\) (Kucherov reaction) first gives an enol. The enol is unstable and rearranges to a carbonyl compound.
Step 2: Key Formula or Approach:
Water adds by Markovnikov rule: the \(-\text{OH}\) goes to the more substituted triple bond carbon.
Step 3: Detailed Explanation:
\(\text{CH}_3-\text{C}\equiv\text{CH} + \text{H}_2\text{O} \to \text{CH}_3-\text{C(OH)}=\text{CH}_2\) (enol).
The enol tautomerises to \(\text{CH}_3-\text{CO}-\text{CH}_3\), propanone (acetone).
Only ethyne gives an aldehyde (acetaldehyde). The alcohols in A and B are not obtained since the enol rearranges to a carbonyl.
Final Answer:
Propyne gives propanone, option (C). \[ \boxed{\text{Propanone}} \]
Addition of water to an alkyne in dilute \(\text{H}_2\text{SO}_4\) with \(\text{HgSO}_4\) (Kucherov reaction) first gives an enol. The enol is unstable and rearranges to a carbonyl compound.
Step 2: Key Formula or Approach:
Water adds by Markovnikov rule: the \(-\text{OH}\) goes to the more substituted triple bond carbon.
Step 3: Detailed Explanation:
\(\text{CH}_3-\text{C}\equiv\text{CH} + \text{H}_2\text{O} \to \text{CH}_3-\text{C(OH)}=\text{CH}_2\) (enol).
The enol tautomerises to \(\text{CH}_3-\text{CO}-\text{CH}_3\), propanone (acetone).
Only ethyne gives an aldehyde (acetaldehyde). The alcohols in A and B are not obtained since the enol rearranges to a carbonyl.
Final Answer:
Propyne gives propanone, option (C). \[ \boxed{\text{Propanone}} \]
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