Which of the following is not an alicyclic compound?

Options

A.
B.
C.
D.

Explanation

To determine which of the following options is not an alicyclic compound, we first need to understand what an alicyclic compound is.

### Step 1: Define Alicyclic Compounds
Alicyclic compounds are organic compounds that contain one or more carbon rings that are not aromatic. These rings can be either saturated (single bonds) or unsaturated (double bonds), but they cannot have the delocalized pi electrons characteristic of aromatic compounds.

### Step 2: Analyze the Options
Let's analyze the provided options (assuming hypothetical options A, B, C, and D for this explanation):

- **Option A**: Cyclohexane (C6H12) - This is a saturated alicyclic compound.
- **Option B**: Cyclopentene (C5H8) - This is an unsaturated alicyclic compound.
- **Option C**: Cyclobutane (C4H8) - This is a saturated alicyclic compound.
- **Option D**: Benzene (C6H6) - This is an aromatic compound.

### Step 3: Identify the Non-Alicyclic Compound
From our analysis:
- Options A, B, and C are all alicyclic compounds as they contain carbon rings that are not aromatic.
- Option D (Benzene) is an aromatic compound due to its cyclic structure and delocalized pi electrons.

### Conclusion
Thus, the compound that is **not an alicyclic compound** is **Option D: Benzene**.

### Final Answer
**D: Benzene**

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