In the following of acetamide derivative the reactivity of `NH_(3)` is greatest towards .

Options

A. acetic anhydride
B. ethyl acetate
C. acetyl chloride
D. acetic acid

Answer

To determine the reactivity of ammonia (NH₃) towards different acetamide derivatives, we need to analyze how the structure of each derivative affects the positive charge density on the carbon atom that is bonded to the carbonyl group (C=O). The more positive charge density on the carbon, the more reactive it will be towards nucleophilic attack by ammonia.

### Step-by-Step Solution:

1. **Identify the Derivatives**: We have four options to consider:
- A) Acidic anhydride (e.g., CH₃CO-O-COCH₃)
- B) Ethyl acetate (e.g., CH₃COOCH₂CH₃)
- C) Acetyl chloride (e.g., CH₃COCl)
- D) Acetic acid (e.g., CH₃COOH)

2. **Understand the Nucleophilic Attack**: Ammonia acts as a nucleophile due to the presence of a lone pair of electrons on the nitrogen atom. It will attack the carbon atom of the carbonyl group (C=O) that has the highest positive charge density.

3. **Analyze Each Option**:
- **Option A (Acidic Anhydride)**: The carbonyl carbon is somewhat stabilized by resonance with the adjacent carbonyl group, which can decrease its positive charge density.
- **Option B (Ethyl Acetate)**: Similar to the anhydride, the carbonyl carbon is stabilized by the ether oxygen, which can also decrease its positive charge density.
- **Option C (Acetyl Chloride)**: The chlorine atom is highly electronegative and exerts a strong -I (inductive) effect, pulling electron density away from the carbonyl carbon. This increases the positive charge density on the carbon, making it more reactive towards nucleophiles.
- **Option D (Acetic Acid)**: The hydroxyl group (-OH) can also stabilize the carbonyl carbon through resonance, which decreases its positive charge density.

4. **Determine the Most Reactive Derivative**: Among the options, acetyl chloride (Option C) has the highest positive charge density on the carbonyl carbon due to the strong -I effect of chlorine. This makes it the most reactive towards nucleophilic attack by ammonia.

5. **Conclusion**: The reactivity of ammonia (NH₃) is greatest towards acetyl chloride (C).

### Final Answer:
The reactivity of NH₃ is greatest towards **acetyl chloride (C)**.