HO-`CH_(2)-CH_(2)`-CH =O `underset(underset((4)Delta)underset((3)H_(2)O^(oplus))((2)H^(oplus)))overset((1)KCN)(rarr)`(A), Product (A) is ,

Options

A.
B.
C.
D.

Answer

To solve the given question, we need to analyze the reaction step by step. The starting material is HO-CH₂-CH₂-CH=O, which is an aldehyde with a hydroxyl group. The reaction involves KCN (potassium cyanide) and H₂O (water) in the presence of H⁺ ions.

### Step-by-Step Solution:

1. **Identify the Starting Material**:
The starting compound is HO-CH₂-CH₂-CH=O. This is a 3-hydroxypropionaldehyde.

2. **Nucleophilic Attack by KCN**:
The cyanide ion (CN⁻) from KCN acts as a nucleophile and attacks the carbonyl carbon of the aldehyde (C=O) group. This results in the formation of a tetrahedral intermediate.

**Hint**: Remember that nucleophiles attack electrophilic centers, such as carbonyl carbons.

3. **Protonation of the Intermediate**:
In the presence of H⁺ ions, one of the hydroxyl groups can be protonated, leading to the formation of an oxonium ion. This intermediate can then undergo hydrolysis.

**Hint**: Protonation increases the electrophilicity of the carbonyl carbon, making it more reactive.

4. **Hydrolysis**:
Water (H₂O) attacks the carbonyl carbon of the oxonium ion, leading to the formation of a new hydroxyl group and the conversion of the carbonyl to a hydroxyl.

**Hint**: Hydrolysis is a reaction where water is used to break bonds, often resulting in the formation of hydroxyl groups.

5. **Formation of a 5-Membered Ring**:
The lone pair on the oxygen can attack the carbonyl carbon, forming a 5-membered cyclic intermediate. This step is crucial as it stabilizes the structure.

**Hint**: Cyclic structures often form in reactions involving nucleophiles and electrophiles due to the stability of ring formations.

6. **Deprotonation**:
The nitrogen in the intermediate can accept a proton, leading to the formation of an amine group. This step is essential for the final product.

**Hint**: Deprotonation is a common step in organic reactions that helps stabilize charged intermediates.

7. **Formation of the Final Product**:
The leaving group (NH₃) departs, and we are left with a double bond between carbon and oxygen (C=O) along with a hydroxyl group (OH) on the adjacent carbon.

**Hint**: The leaving group is often a good nucleophile or a stable molecule that can depart without destabilizing the product.

8. **Final Structure**:
The final product A is a compound with a carbonyl group (C=O) and a hydroxyl group (OH) adjacent to it, which corresponds to the structure of a 5-membered ring compound.

### Conclusion:
The product A formed from the reaction is a 5-membered cyclic compound with a hydroxyl group and a carbonyl group.

### Final Product:
The final product A is **5-hydroxy-2-oxopentanenitrile**.