Which one is not aromatic compound ?

Options

A.
B.
C.
D.

Answer

To determine which compound is not aromatic, we need to follow a systematic approach based on the criteria for aromaticity. Aromatic compounds must satisfy the following conditions:

1. **Cyclic Structure**: The compound must be cyclic.
2. **Planarity**: The compound must be planar to allow for overlap of p-orbitals.
3. **Conjugation**: The compound must have a continuous overlap of p-orbitals (conjugation).
4. **Hückel's Rule**: The compound must have \(4n + 2\) π electrons, where \(n\) is a non-negative integer.

### Step-by-Step Solution:

1. **Identify the Compounds**: List the compounds provided in the question. For the sake of this solution, let's assume we have four compounds to analyze.

2. **Check for Cyclic Structure**: Determine if each compound is cyclic. If any compound is not cyclic, it cannot be aromatic.

3. **Check for Planarity**: For each cyclic compound, check if it is planar. If it is not planar, it cannot be aromatic.

4. **Check for Conjugation**: Analyze the structure of each compound to see if there is a continuous overlap of p-orbitals. This is typically seen in compounds with alternating single and double bonds.

5. **Count the π Electrons**: For each compound that is cyclic, planar, and has conjugation, count the number of π electrons.

6. **Apply Hückel's Rule**: Use Hückel's rule to determine if the number of π electrons fits the formula \(4n + 2\). If it does, the compound is aromatic. If it has \(4n\) π electrons, it is anti-aromatic. If it does not fit either condition, it is non-aromatic.

7. **Identify the Non-Aromatic Compound**: After analyzing all compounds, identify which one does not meet the criteria for aromaticity.

### Conclusion:
Based on the analysis, if we find a compound that does not satisfy Hückel's rule or does not have the required π electrons, that compound is the answer to the question of which one is not aromatic.