The compound which is not resonance stabilised

Options

A. `CH_(2)=CH-Cl`
B.
C. `CH_(2)=CH-CH_(2)Cl`
D.

Answer

To determine which compound is not resonance stabilized, we will analyze each option step by step.

### Step 1: Analyze the first compound
- The first compound has a structure with a double bond between carbon atoms and a chlorine atom attached.
- Chlorine has lone pairs of electrons that can participate in resonance.
- The lone pair on chlorine can donate electrons to the double bond, creating a resonance structure where the double bond shifts and charges are distributed.
- **Conclusion**: This compound is resonance stabilized.

**Hint**: Look for lone pairs on atoms that can participate in resonance by donating electrons.

### Step 2: Analyze the second compound
- The second compound has an oxygen atom with a negative charge and double bonds.
- The negative charge on oxygen can shift to form resonance structures.
- The negative charge can be delocalized through the double bonds, allowing for multiple resonance forms.
- **Conclusion**: This compound is also resonance stabilized.

**Hint**: Check for negative charges or lone pairs that can shift to create resonance structures.

### Step 3: Analyze the third compound
- The third compound has a structure with a double bond and a chlorine atom attached to a carbon chain.
- Although there are lone pairs on chlorine, the structure lacks a proper conjugated system.
- The presence of the carbon chain disrupts the ability to delocalize electrons effectively, leading to a loss of conjugation.
- **Conclusion**: This compound does not undergo resonance stabilization.

**Hint**: Identify if there is a continuous system of overlapping p-orbitals; if not, resonance may not occur.

### Step 4: Analyze the fourth compound
- The fourth compound has a nitrogen atom with a lone pair.
- The lone pair on nitrogen can participate in resonance by donating electrons to adjacent double bonds.
- This allows for the formation of resonance structures.
- **Conclusion**: This compound is resonance stabilized.

**Hint**: Look for atoms with lone pairs adjacent to double bonds that can participate in resonance.

### Final Conclusion
After analyzing all the compounds, we find that the third compound is the only one that is not resonance stabilized.

**Answer**: The compound which is not resonance stabilized is the third compound.