Choose the false statement

Options

A. `-NH_(2)` strongly activating while `-NHCOCH_(3)` is weak activating
B. `-NO_(2)` is strong deactivating group
C. `-NHCOCH_(3)` and `-NO_(2)` are m-directing groups
D. `-NH_(3)` and `-NO_(2)` are m-directing groups.

Answer

To solve the question of identifying the false statement regarding amines and their effects on benzene rings, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement 1: NH2 is a strong activating group while NHCOCH3 is a weak activating group.**
- The amino group (NH2) has a lone pair of electrons that can participate in resonance with the benzene ring. This increases the electron density on the ring, making it more reactive towards electrophilic substitution reactions. Therefore, NH2 is indeed a strong activating group.
- The group NHCOCH3 (acetanilide) has a carbonyl (C=O) that withdraws electron density due to its electronegativity. Although NHCOCH3 can still donate some electron density through resonance, it is less effective than NH2. Thus, it is classified as a weak activating group.
- **Conclusion:** This statement is **true**.

2. **Statement 2: NO2 is a strong deactivating group.**
- The nitro group (NO2) is known to be a strong electron-withdrawing group due to its -I (inductive) and -M (mesomeric) effects. It decreases the electron density of the benzene ring, making it less reactive towards electrophiles.
- **Conclusion:** This statement is **true**.

3. **Statement 3: NHCOCH3 and NO2 are meta-directing.**
- The nitro group (NO2) is indeed a meta-directing group because it withdraws electron density from the ortho and para positions, making them less reactive compared to the meta position.
- However, NHCOCH3 is not a deactivating group; it is a weak activating group and directs electrophilic substitution to the ortho and para positions due to its ability to donate electron density through resonance.
- **Conclusion:** This statement is **false**.

4. **Statement 4: NH3 and NO2 are meta-directing.**
- The nitro group (NO2) is confirmed to be meta-directing as previously discussed.
- NH3 (ammonia) can be considered as a weakly activating group, but when it forms a quaternary ammonium ion (due to the formation of four bonds), it can act as an electron-withdrawing group, leading to meta-directing behavior.
- **Conclusion:** This statement is **true**.

### Final Conclusion:
The false statement among the options provided is **Statement 3: NHCOCH3 and NO2 are meta-directing.**

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