Which of the following has the greatest angle strain ?

Options

A. methyl cyclobutane
B. methyl cyclopentne
C. methyl cyclohexane
D. methyl cyclopropane

Answer

To determine which of the given compounds has the greatest angle strain, we need to analyze the structures of the cyclic compounds mentioned: methyl cyclobutane, methyl cyclopentane, and methyl cyclohexane.

### Step-by-Step Solution:

1. **Understand Angle Strain**: Angle strain occurs in cyclic compounds when the bond angles deviate from the ideal tetrahedral angle of 109.5° for sp³ hybridized carbon atoms. The more the bond angles deviate from this ideal angle, the greater the angle strain.

2. **Identify the Structures**:
- **Methyl Cyclobutane**: This compound has a four-membered ring. The ideal bond angle in a tetrahedral structure is 109.5°, but in a cyclobutane, the bond angles are approximately 90°, leading to significant angle strain.
- **Methyl Cyclopentane**: This compound has a five-membered ring. The bond angles in cyclopentane are closer to the ideal tetrahedral angle, around 108°, which means it has less angle strain compared to cyclobutane.
- **Methyl Cyclohexane**: This compound has a six-membered ring. Cyclohexane can adopt a chair conformation that allows for bond angles very close to 109.5°, resulting in minimal angle strain.

3. **Compare Angle Strain**:
- Methyl cyclobutane has the highest angle strain due to its four-membered ring with bond angles significantly less than 109.5°.
- Methyl cyclopentane has moderate angle strain, as its bond angles are closer to the ideal angle.
- Methyl cyclohexane has the least angle strain due to its ability to adopt a conformation that minimizes strain.

4. **Conclusion**: Among the compounds listed, **methyl cyclobutane** has the greatest angle strain due to its smaller ring size and the significant deviation of its bond angles from the ideal tetrahedral angle.

### Final Answer:
**Methyl cyclobutane has the greatest angle strain.**