Question

Among the following, the molecule which shows aromatic character is:

• A. \text{Benzene (C}_6\text{H}_6\text{)}
• B. \text{Cyclohexene}
• C. \text{Cycloheptatriene}
• D. \text{Cyclooctatetraene}

Hint:

When identifying aromatic compounds, always check the number of \(\pi\)-electrons in the conjugated system. The compound must satisfy Huckel’s rule to be aromatic.

Answer 1

The Correct Option is A

Aromatic compounds are characterized by a conjugated system of \(\pi\)-electrons that follows Huckel’s rule: the number of \(\pi\)-electrons should be \(4n + 2\), where \(n\) is a non-negative integer.
Among the given options:
- Benzene (\(C_6H_6\)) has 6 \(\pi\)-electrons, which satisfies Huckel’s rule (\(n = 1\), giving \(4n + 2 = 6\)). Hence, benzene is aromatic.
- Cyclohexene has a non-conjugated \(\pi\)-system and is not aromatic.
- Cycloheptatriene is antiaromatic due to its 6 \(\pi\)-electrons (it has a \(4n\) structure).
- Cyclooctatetraene is also antiaromatic due to its 8 \(\pi\)-electrons (following \(4n\)).
Thus, the molecule that shows aromatic character is benzene.
\[ C_6H_6 : 6 \pi \text{electrons} \rightarrow \text{Aromatic} \]