Acetophenone when reacted with a base, `C_(2)H_(5)ONa,` yields a stable compound which has the structure :

Options

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D.

Explanation

To solve the problem of what stable compound acetophenone yields when reacted with the base C2H5ONa, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are:
- Acetophenone (C6H5C(O)CH3)
- Sodium ethoxide (C2H5ONa), which dissociates into C2H5O⁻ and Na⁺.

### Step 2: Structure of Acetophenone
Acetophenone has the following structure:
- A phenyl group (C6H5) attached to a carbonyl group (C=O) and a methyl group (CH3).

### Step 3: Mechanism of Reaction
1. **Deprotonation**: The base (C2H5O⁻) will deprotonate the alpha hydrogen of acetophenone, forming an enolate ion. The enolate ion is more nucleophilic and can attack the carbonyl carbon of another acetophenone molecule.

2. **Nucleophilic Attack**: The enolate ion attacks the carbonyl carbon of another molecule of acetophenone, leading to the formation of a β-hydroxy ketone (an aldol product).

### Step 4: Formation of Aldol Product
- The aldol product formed will have the structure:
- C6H5C(OH)(CH3)C(O)CH2C6H5
- This product contains a hydroxyl group (-OH) and a ketone group (C=O).

### Step 5: Dehydration
- The aldol product can undergo dehydration (loss of water) to form an α,β-unsaturated ketone. This step typically involves the removal of a water molecule, resulting in a double bond between the alpha and beta carbons.

### Step 6: Final Structure
- The final stable compound after dehydration will have the following structure:
- C6H5C=CHC(O)CH3
- This compound is known as an α,β-unsaturated ketone.

### Conclusion
The stable compound formed from the reaction of acetophenone with sodium ethoxide is an α,β-unsaturated ketone. The structure can be summarized as follows:
- **Final Structure**: C6H5C=CHC(O)CH3