The most reactive among the following towards sulphonation is

Options

A. toluene
B. chlorobenzene
C. nitrobenzene
D. m - Xylene

Answer

To determine the most reactive compound towards sulfonation among the given options (A: Toluene, B: Chlorobenzene, C: Nitrobenzene, D: Meta Xylene), we need to analyze the electronic effects of substituents on the benzene ring and how they influence nucleophilicity.

### Step-by-Step Solution:

1. **Understanding Sulfonation**:
- Sulfonation involves the electrophilic substitution of a sulfonyl group (SO3) onto an aromatic compound. The electrophile (SO3) will be attacked by a nucleophile, which in this case is the aromatic ring.

2. **Identify the Compounds**:
- A: Toluene (C6H5CH3)
- B: Chlorobenzene (C6H5Cl)
- C: Nitrobenzene (C6H5NO2)
- D: Meta Xylene (C6H4(CH3)2)

3. **Analyze Each Compound**:
- **Toluene (A)**: The methyl group (CH3) is an electron-donating group (+I effect), which increases the electron density on the benzene ring, making it more nucleophilic and reactive towards electrophiles.

- **Chlorobenzene (B)**: The chlorine atom has a +M effect (resonance donation) but also a -I effect (inductive withdrawal). The net effect is a decrease in electron density on the ring, making it less reactive than toluene.

- **Nitrobenzene (C)**: The nitro group (NO2) is a strong electron-withdrawing group (-M effect), which significantly decreases the electron density on the ring, making it the least reactive towards sulfonation.

- **Meta Xylene (D)**: This compound has two methyl groups. Methyl groups are +I donors, which increases the electron density on the ring. The presence of two methyl groups enhances the nucleophilicity even more compared to toluene.

4. **Compare Reactivity**:
- Toluene has increased nucleophilicity due to one methyl group.
- Chlorobenzene has decreased nucleophilicity due to the combined effects of chlorine.
- Nitrobenzene has the lowest nucleophilicity due to the strong electron-withdrawing effect of the nitro group.
- Meta Xylene, with two methyl groups, has the highest nucleophilicity due to the combined +I effects.

5. **Conclusion**:
- Among the given compounds, **Meta Xylene (D)** is the most reactive towards sulfonation due to the presence of two electron-donating methyl groups, which significantly increase the electron density on the aromatic ring.

### Final Answer:
**D: Meta Xylene** is the most reactive towards sulfonation.