Which of the following group has the maximum hyperconjugation effect ?

Options

A. CH3-
B. CH3CH2-
C. (CH3)2CH-
D. (CH3)3C-

Answer

To determine which group has the maximum hyperconjugation effect, we need to analyze the options provided in the question. Hyperconjugation is the interaction between the electrons in a σ-bond (usually C-H or C-C) and an adjacent empty or partially filled p-orbital or π-bond. This effect stabilizes the molecule.

### Step-by-Step Solution:

1. **Understand Hyperconjugation**:
Hyperconjugation occurs when the σ-bonds (C-H or C-C) of an alkyl group interact with an adjacent π-bond or an empty p-orbital. The more alkyl groups attached to a carbon atom, the greater the hyperconjugation effect due to the increased number of C-H bonds that can participate in this interaction.

2. **Identify the Groups**:
The groups mentioned in the question are:
- CH3 (methyl group)
- CH2 (methylene group)
- CH3-CH (isopropyl group)
- CH3-CH(CH3)2 (tertiary butyl group)

3. **Count the C-H Bonds**:
- **Methyl Group (CH3)**: 3 C-H bonds
- **Methylene Group (CH2)**: 2 C-H bonds
- **Isopropyl Group (CH3-CH)**: 6 C-H bonds (3 from CH3 and 3 from CH adjacent to the carbon)
- **Tertiary Butyl Group (CH3-CH(CH3)2)**: 9 C-H bonds (3 from each of the three CH3 groups)

4. **Evaluate the Hyperconjugation**:
The more C-H bonds that can participate in hyperconjugation, the greater the stabilization effect. Thus:
- Methyl (3 C-H bonds)
- Methylene (2 C-H bonds)
- Isopropyl (6 C-H bonds)
- Tertiary Butyl (9 C-H bonds)

5. **Conclusion**:
The tertiary butyl group (CH3-CH(CH3)2) has the maximum number of C-H bonds (9), leading to the maximum hyperconjugation effect.

### Final Answer:
The group with the maximum hyperconjugation effect is the **tertiary butyl group (CH3-CH(CH3)2)**.

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