Maximum dehydration takes place in that of

Options

A.
B.
C.
D.

Answer

To determine where maximum dehydration takes place among the given options, we need to analyze the structures and the stability of the resulting carbocations after the removal of water (dehydration).

### Step-by-Step Solution:

1. **Understanding Dehydration**: Dehydration is the process of removing water (H₂O) from a compound. In organic chemistry, this often involves the formation of a double bond (alkene) from an alcohol.

2. **Analyzing Each Option**:
- **Option 1**: Cyclohexanone with an OH group.
- The carbonyl group (C=O) does not allow for the removal of an acidic hydrogen easily. The hydrogen attached to the sp³ hybridized carbon is not acidic enough to facilitate dehydration effectively.

- **Option 2**: Another compound with a carbonyl group and an OH group.
- The presence of alpha hydrogens (hydrogens on the carbon adjacent to the carbonyl) makes them acidic. When the OH group is protonated, it can lead to the formation of a stable carbocation upon dehydration. The resulting structure can undergo further stabilization through resonance (conjugation), making it more favorable for dehydration.

- **Option 3**: A structure with a carbonyl and an OH group.
- Similar to option 1, the removal of OH leads to a carbocation, but the hydrogen involved is not alpha, and thus does not provide the necessary stability or acidity for effective dehydration.

- **Option 4**: A structure with a cyclohexane-like structure and an OH group.
- The carbocation formed here is not stabilized effectively due to the lack of conjugation and the position of the hydrogen being non-acidic.

3. **Conclusion**: After analyzing all options, option 2 is the most favorable for maximum dehydration due to the presence of acidic alpha hydrogens and the ability to stabilize the resulting carbocation through resonance.

### Final Answer:
**Option 2 is the correct answer for maximum dehydration.**