Question

Identify the Carbonyl compound which will not be formed when hydration of Alkynes is carried out with dil. \( H_2SO_4/Hg^{2+} \) at 333 K. Acetone, Butanal, Ethanal, Butanone.

• A. Acetone
• B. Butanone
• C. Butanal
• D. Ethanal

Hint:

Hydration of alkynes in presence of \( Hg^{2+}/H_2SO_4 \) gives ketones via enol-keto tautomerismAldehydes are not formed in this reaction.

Answer 1

The Correct Option is C

Step 1: Understand hydration of alkynes.
In presence of dil. \( H_2SO_4/Hg^{2+} \), alkynes undergo Markovnikov addition of water.
The product initially formed is an enol, which tautomerizes to a ketone.

Step 2: Key rule of reaction.
Terminal alkynes give methyl ketones.
Internal alkynes give ketones.
Aldehydes are generally not formed in this reaction.

Step 3: Analyze given compounds.
Acetone and Butanone are ketones and can be formed by hydration of alkynes.
Ethanal can be formed from acetylene under specific hydration conditions.
Butanal is an aldehyde and cannot be formed by this method.

Step 4: Conclusion.
Thus, the compound that will not be formed is Butanal.
\[ \boxed{\text{Butanal}} \]