Which of the following group(s) activate the benzene ring towards electrophilic substitution reaction.

Options

A. `-Cl`
B.
C. `-O-overset(O)overset("||")(C)-CH_(3)`
D. `-C equiv overset(..)N`

Answer

To determine which groups activate the benzene ring towards electrophilic substitution reactions, we need to analyze the nature of the substituents attached to the benzene ring. Here’s a step-by-step solution:

### Step 1: Understand the Activation and Deactivation of the Benzene Ring
- **Activation**: Groups that donate electron density to the benzene ring increase its reactivity towards electrophiles. These groups are known as activating groups.
- **Deactivation**: Groups that withdraw electron density from the benzene ring decrease its reactivity towards electrophiles. These groups are known as deactivating groups.

### Step 2: Identify Electron Donating and Withdrawing Groups
- **Electron Donating Groups**: These groups typically have lone pairs of electrons that can be delocalized into the benzene ring. Examples include -OH, -NH2, -OCH3, etc.
- **Electron Withdrawing Groups**: These groups pull electron density away from the benzene ring. Examples include -NO2, -CN, -COOH, -Cl, etc.

### Step 3: Analyze Each Option
1. **Chlorine (Cl)**:
- Chlorine has a high electronegativity and exhibits a -I (inductive) effect, which withdraws electrons. Thus, it deactivates the ring despite having lone pairs that can participate in resonance.
- **Conclusion**: Deactivates the ring.

2. **Nitrogen (N)**:
- If nitrogen is part of an amine group (-NH2) or similar, it can donate its lone pair to the ring, increasing electron density and activating the ring.
- **Conclusion**: Activates the ring.

3. **OCO-CS3 (Acetoxy group)**:
- The oxygen has lone pairs that can participate in resonance with the benzene ring, increasing electron density. Although the carbonyl group can withdraw electrons, the overall effect is still activation due to resonance.
- **Conclusion**: Activates the ring.

4. **Cyanide (CN)**:
- The cyanide group is a strong electron-withdrawing group due to its -I and -M effects, which significantly reduce the electron density on the benzene ring.
- **Conclusion**: Deactivates the ring.

### Final Conclusion
Based on the analysis:
- **Activating Groups**: Nitrogen (N) and OCO-CS3 (Acetoxy group).
- **Deactivating Groups**: Chlorine (Cl) and Cyanide (CN).

### Answer:
The groups that activate the benzene ring towards electrophilic substitution reactions are:
- Option 2 (Nitrogen)
- Option 3 (OCO-CS3)

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