Which of the following has maximum angle strain ?

Options

A. Propane
B. Cyclopropane
C. n - butane
D. Cyclobutane

Answer

To determine which of the given compounds has the maximum angle strain, we will analyze the structures of the compounds mentioned: propane, cyclopropane, and cyclobutane.

### Step-by-Step Solution:

1. **Identify the Structures**:
- **Propane**: Propane is an open-chain alkane with the formula C3H8 (CH3-CH2-CH3). It has a linear structure with no angle strain because the carbon atoms can freely rotate around their bonds.
- **Cyclopropane**: Cyclopropane is a cyclic compound with three carbon atoms arranged in a triangle. The bond angles in cyclopropane are approximately 60 degrees.
- **Cyclobutane**: Cyclobutane is another cyclic compound with four carbon atoms arranged in a square-like structure. The bond angles in cyclobutane are approximately 90 degrees.

2. **Determine the Ideal Bond Angles**:
- For sp3 hybridized carbon atoms, the ideal bond angle is 109.5 degrees. This is the angle that carbon atoms prefer to adopt to minimize strain.

3. **Calculate Angle Strain**:
- **Propane**: Since propane is an open-chain alkane, it does not have angle strain. The carbon atoms can rotate freely, allowing them to adopt angles close to 109.5 degrees.
- **Cyclopropane**: The bond angles are 60 degrees, which is significantly less than the ideal angle of 109.5 degrees. The angle strain can be calculated as:
\[ \text{Angle Strain} = 109.5^\circ - 60^\circ = 49.5^\circ \]
- **Cyclobutane**: The bond angles are 90 degrees, which is also less than the ideal angle. The angle strain can be calculated as:
\[ \text{Angle Strain} = 109.5^\circ - 90^\circ = 19.5^\circ \]

4. **Compare Angle Strain**:
- Cyclopropane has an angle strain of 49.5 degrees.
- Cyclobutane has an angle strain of 19.5 degrees.
- Propane has no angle strain.

5. **Conclusion**:
- Among the compounds analyzed, cyclopropane has the maximum angle strain due to its significantly smaller bond angles compared to the ideal sp3 hybridized angle.

### Final Answer:
**Cyclopropane has the maximum angle strain.**