Which of the following is most reactive towards nucleophilic substritution reaction?

Options

A. Ethyl acetate
B. Acetic anhydride
C. Acetamide
D. Acetyl chloride

Answer

To determine which compound is most reactive towards nucleophilic substitution reactions, we need to analyze the structures of the given compounds and their ability to stabilize the transition state during the nucleophilic attack. The compounds in question are:

1. Ethyl Acetate (CH3C(=O)OCH2CH3)
2. Acetic Anhydride (CH3C(=O)O(C=O)CH3)
3. Acetamide (CH3C(=O)NH2)
4. Acetyl Chloride (CH3C(=O)Cl)

### Step-by-Step Solution:

**Step 1: Identify the Electrophilic Center**
- In all the compounds, the carbonyl carbon (C=O) is the electrophilic center where nucleophilic substitution will occur. This carbon is electron-deficient due to the electronegativity of the oxygen atom.

**Step 2: Analyze Electron-Withdrawing and Electron-Donating Effects**
- The reactivity of the carbonyl carbon towards nucleophiles depends on its electron deficiency. Electron-withdrawing groups increase the electron deficiency of the carbonyl carbon, making it more reactive towards nucleophiles.

**Step 3: Examine Each Compound**
1. **Ethyl Acetate**: The -O- group donates electron density to the carbonyl carbon, reducing its electron deficiency. Thus, it is less reactive.

2. **Acetic Anhydride**: Contains two carbonyl groups, but both carbonyls have oxygen atoms that can donate electron density. This reduces the overall electron deficiency of the carbonyl carbons, making it less reactive.

3. **Acetamide**: The nitrogen atom in the amide has a lone pair that can donate electron density to the carbonyl carbon, which also decreases its electron deficiency. Therefore, it is less reactive.

4. **Acetyl Chloride**: The chlorine atom is highly electronegative and exerts a -I (inductive) effect, pulling electron density away from the carbonyl carbon. This increases the electron deficiency of the carbonyl carbon, making it more reactive towards nucleophiles. Additionally, chlorine is a good leaving group.

**Step 4: Conclusion**
- Among the four compounds, **Acetyl Chloride** is the most reactive towards nucleophilic substitution reactions due to the electron-withdrawing effect of chlorine and its ability to act as a good leaving group.

### Final Answer:
**Acetyl Chloride (CH3C(=O)Cl) is the most reactive towards nucleophilic substitution reactions.**