Among the following compounds the one that is most reactive towards electrophilic nitration is

Options

A. Toluene
B. Benzene
C. Benzoic acid
D. Nitrobenzene

Explanation

To determine which compound is most reactive towards electrophilic nitration among toluene, benzene, benzoic acid, and nitrobenzene, we need to analyze the effects of substituents on the benzene ring and how they influence electron density.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- Toluene: Benzene ring with a methyl (CH₃) group.
- Benzene: A simple benzene ring with no substituents.
- Benzoic Acid: Benzene ring with a carboxylic acid (–COOH) group.
- Nitrobenzene: Benzene ring with a nitro (–NO₂) group.

2. **Understand Electrophilic Nitration**:
- Electrophilic nitration involves the attack of an electrophile (NO₂⁺) on the benzene ring.
- The reactivity of the benzene ring towards electrophiles depends on the electron density of the ring. Higher electron density increases reactivity.

3. **Analyze the Effects of Substituents**:
- **Toluene (CH₃ group)**: The methyl group is an electron-donating group (+I effect). It increases the electron density of the benzene ring, making it more reactive towards electrophiles.
- **Benzene**: No substituents mean it has a standard level of electron density.
- **Benzoic Acid (–COOH group)**: The carboxylic acid group is an electron-withdrawing group (–I effect). It decreases the electron density of the benzene ring, making it less reactive towards electrophiles.
- **Nitrobenzene (–NO₂ group)**: The nitro group is also an electron-withdrawing group (–I effect). It significantly decreases the electron density of the benzene ring, making it the least reactive towards electrophiles.

4. **Compare Reactivity**:
- Toluene has the highest electron density due to the +I effect of the methyl group.
- Benzene has moderate reactivity.
- Benzoic acid and nitrobenzene have decreased reactivity due to their electron-withdrawing effects.

5. **Conclusion**:
- Among the given compounds, **toluene** is the most reactive towards electrophilic nitration due to the electron-donating effect of the methyl group.

### Final Answer:
**Toluene is the most reactive towards electrophilic nitration.**