Which alkyne will produce aldehyde by hydration in presence of HgSO4 and H2SO4?

Hex-2-yne

Ethyne

But-2-yne

Propyne

Solution

Correct option is B

The correct answer is (B) Ethyne

Explanation:

Ethyne (acetylene) undergoes hydration in the presence of mercury(II) sulfate (HgSO₄) and sulfuric acid (H₂SO₄) to produce acetaldehyde (CH₃CHO). This reaction involves a Markovnikov addition, where the water adds to the alkyne, resulting in the formation of an aldehyde.

Information Booster:

The reaction is known as hydroboration-oxidation of alkynes.
In the presence of HgSO₄ and H₂SO₄, Ethyne undergoes Markovnikov's rule for the addition of water.
The product formed is acetaldehyde, a simple aldehyde.
This reaction is commonly used in industrial processes for producing aldehydes.
Ethyne (acetylene) is a simple alkyne that readily reacts with water under acidic conditions.

The reaction occurs through an intermediate enol, which tautomerizes to form the aldehyde.

Additional Information:

Hex-2-yne: Under the same conditions, it produces a ketone rather than an aldehyde.
But-2-yne: Similarly, this alkyne produces a ketone and does not yield an aldehyde.
Propyne: Like other alkynes, it also produces a ketone rather than an aldehyde under these conditions.