Which is maximum reactive towords acid catalysed dehydration :

Options

A.
B.
C.
D.

Answer

To determine which compound is the most reactive towards acid-catalyzed dehydration, we will analyze the stability of the carbocations formed during the reaction for each option. The more stable the carbocation, the more reactive the compound will be.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have four different compounds to analyze for their reactivity towards acid-catalyzed dehydration.

2. **Mechanism of Acid-Catalyzed Dehydration**: In acid-catalyzed dehydration, the hydroxyl group (OH) is protonated by H⁺, leading to the formation of water (H₂O) which leaves, resulting in the formation of a carbocation.

3. **Analyze Each Compound**:
- **Compound 1**: After protonation of the OH group, a carbocation is formed on the adjacent carbon. The stability of this carbocation will depend on its structure.
- **Compound 2**: This compound has a cyclic structure. Upon protonation, the carbocation formed is on a sp² carbon which is less stable due to the ring strain and the electronegativity of the sp carbon.
- **Compound 3**: This compound has a benzene ring attached to the carbon with the OH group. The carbocation formed can be stabilized by resonance with the benzene ring, making it more stable than the previous compounds.
- **Compound 4**: This compound allows for resonance stabilization of the carbocation formed after dehydration. The positive charge can be delocalized over multiple atoms, leading to a very stable carbocation.

4. **Compare the Stability of Carbocations**:
- **Compound 1**: Moderate stability.
- **Compound 2**: Least stable due to ring strain.
- **Compound 3**: More stable due to resonance with the benzene ring.
- **Compound 4**: Most stable due to extensive resonance stabilization.

5. **Conclusion**: The compound that forms the most stable carbocation after dehydration is Compound 4. Therefore, it is the most reactive towards acid-catalyzed dehydration.

### Final Answer: Compound 4 is the most reactive towards acid-catalyzed dehydration.