When acetylene is passed through dil. `H_(2)SO_(4)` in the presence of `HgSO_(4)`, the compound formed is

Options

A. Acetic acid
B. Ketone
C. Ether
D. Acetaldehyde

Answer

To determine the compound formed when acetylene (C₂H₂) is passed through dilute H₂SO₄ in the presence of HgSO₄, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are:
- Acetylene (C₂H₂)
- Dilute sulfuric acid (H₂SO₄)
- Mercury(II) sulfate (HgSO₄)

### Step 2: Understand the Reaction Mechanism
This reaction is known as the oxymercuration-demercuration reaction. In this process, the acetylene undergoes hydration in the presence of HgSO₄, which facilitates the addition of water (H₂O) across the triple bond of acetylene.

### Step 3: Addition of Water
When acetylene reacts with dilute H₂SO₄ and HgSO₄, water is added across the triple bond. The reaction can be represented as follows:
\[ \text{C}_2\text{H}_2 + \text{H}_2\text{SO}_4 \xrightarrow{\text{HgSO}_4} \text{CH}_2\text{=CH-OH} \]
This intermediate product is known as vinyl alcohol (or enol).

### Step 4: Rearrangement to Form Aldehyde
The vinyl alcohol (CH₂=CH-OH) is unstable and undergoes tautomerization to form acetaldehyde (CH₃CHO). The rearrangement involves the migration of the hydrogen atom and the conversion of the double bond:
\[ \text{CH}_2\text{=CH-OH} \rightarrow \text{CH}_3\text{CHO} \]
This results in the formation of acetaldehyde.

### Step 5: Conclusion
Thus, the compound formed when acetylene is passed through dilute H₂SO₄ in the presence of HgSO₄ is acetaldehyde (CH₃CHO).

### Final Answer:
The compound formed is **acetaldehyde (CH₃CHO)**.

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