Which of the following is a non-aromatic compound ?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds is non-aromatic, we will apply Huckel's rule of aromaticity. The key points to consider are:

1. The compound must be cyclic.
2. The compound must be planar.
3. The compound must have a conjugated system (alternating single and double bonds).
4. The compound must have an odd number of π (pi) electrons.

Now, let's analyze each option step by step:

### Step 1: Analyze Option A
- **Cyclic**: Yes, it is a cyclic compound.
- **Planar**: No, it is non-planar.
- **Conjugated**: Not applicable since it is non-planar.
- **Conclusion**: Since it does not meet the planar requirement, **Option A is non-aromatic**.

### Step 2: Analyze Option B
- **Cyclic**: Yes, it is a cyclic compound.
- **Planar**: Yes, it is planar.
- **Conjugated**: No, there is no conjugation in the ring.
- **Conclusion**: Since it does not have a conjugated system, **Option B is also non-aromatic**.

### Step 3: Analyze Option C
- **Cyclic**: Yes, it is a cyclic compound.
- **Planar**: Yes, it is planar.
- **Conjugated**: Yes, it has alternating double bonds.
- **Pi Electrons**: It has an even number of π electrons (4).
- **Conclusion**: Since it has an even number of π electrons, **Option C is anti-aromatic**.

### Step 4: Analyze Option D
- **Cyclic**: Yes, it is a cyclic compound.
- **Planar**: Yes, it is planar.
- **Conjugated**: Yes, it has a conjugated system.
- **Pi Electrons**: It has an odd number of π electrons (3).
- **Conclusion**: Since it meets all the criteria for aromaticity, **Option D is aromatic**.

### Final Conclusion
The non-aromatic compounds among the options are **Option A and Option B**.

---