Predict the product 'B' in the sequence of reaction `HC equiv CH overset (30% H_(2) SO_(4))underset(Hg SO_(4)) to A overset (NaOH) to B`

Options

A. `CH_3COONa`
B. `CH_3COOH`
C. `CH_3CHO`
D. `CH_3CH(OH)CH_2CHO`

Answer

To predict the product 'B' in the sequence of reactions given, we will break down the process step by step.

### Step 1: Identify the starting material
The starting material is ethyne (HC≡CH), which is an alkyne.

### Step 2: Reaction with H2SO4 and HgSO4
When ethyne reacts with 30% H2SO4 in the presence of HgSO4, it undergoes hydration. This reaction leads to the formation of an aldehyde. The product formed is acetaldehyde (CH3CHO).

**Chemical Reaction:**
\[ \text{HC≡CH} + H_2SO_4 \xrightarrow{HgSO_4} \text{CH}_3\text{CHO} \]

### Step 3: Identify the product 'A'
The product 'A' from the first step is acetaldehyde (CH3CHO).

### Step 4: Reaction with NaOH
The next step involves the reaction of acetaldehyde with NaOH. Acetaldehyde contains alpha hydrogens, which allows it to undergo aldol condensation in the presence of a base like NaOH.

### Step 5: Aldol Condensation
In aldol condensation, two molecules of acetaldehyde react to form a β-hydroxy aldehyde. The aldol product formed from two molecules of acetaldehyde is 3-hydroxybutanal (CH3CH(OH)CH2CHO).

**Chemical Reaction:**
\[ 2 \text{CH}_3\text{CHO} \xrightarrow{NaOH} \text{CH}_3\text{CH(OH)CH}_2\text{CHO} \]

### Step 6: Final Product 'B'
The final product 'B' after aldol condensation is 3-hydroxybutanal (also known as 3-hydroxybutyric aldehyde).

### Summary of the Reaction Sequence
1. Ethyne (HC≡CH) reacts with H2SO4 and HgSO4 to form acetaldehyde (CH3CHO).
2. Acetaldehyde reacts with NaOH to undergo aldol condensation, yielding 3-hydroxybutanal (CH3CH(OH)CH2CHO).

Thus, the product 'B' is 3-hydroxybutanal.

### Final Answer
The answer is 3-hydroxybutanal.

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