Hyperconjugation is defined as No bond resonance. The concept of hyperconjugation arose from the discovery of electron releasing pattern for alkyl groups. It involves `sigma` electrons of C-H bond. Greater the number of C-H bond (`alpha`-hydrogen atom w.r.t. double bond) more will be hyperconjugative structures, more will be stability Heat of hydrogenation of alkene are affected by hyperconjugative effects.
Which of the following has highest heat of hydrogenation?

Options

A. (a)
B. (b)
C. (c)
D. (d)

Answer

To determine which alkene has the highest heat of hydrogenation, we need to analyze the number of hyperconjugative structures available for each alkene based on the number of alpha-hydrogens (C-H bonds) present. The more hyperconjugative structures an alkene has, the more stable it is, and consequently, the higher the heat of hydrogenation.

### Step-by-Step Solution:

1. **Understanding Hyperconjugation**:
- Hyperconjugation involves the interaction of σ electrons of C-H bonds with an adjacent π bond. The more C-H bonds (alpha-hydrogens) adjacent to the double bond, the more hyperconjugative structures can be formed.

2. **Identify the Alkene Structures**:
- Let's denote the alkenes as A, B, C, and D. We will analyze each alkene to count the number of C-H bonds that are alpha to the double bond.

3. **Count Alpha-Hydrogens in Each Alkene**:
- **Alkene A**:
- It has 5 C-H bonds (2 on one side of the double bond and 3 on the other side).
- Therefore, it can form 5 hyperconjugative structures.

- **Alkene B**:
- It has 4 C-H bonds (2 alpha-hydrogens on one side and 2 on the other side).
- Therefore, it can form 4 hyperconjugative structures.

- **Alkene C**:
- It has 6 C-H bonds (2 alpha-hydrogens on each side of the double bond).
- Therefore, it can form 6 hyperconjugative structures.

- **Alkene D**:
- It has 4 C-H bonds (2 alpha-hydrogens on each side of the double bond).
- Therefore, it can form 4 hyperconjugative structures.

4. **Comparing the Number of Hyperconjugative Structures**:
- Alkene A: 5 hyperconjugative structures
- Alkene B: 4 hyperconjugative structures
- Alkene C: 6 hyperconjugative structures
- Alkene D: 4 hyperconjugative structures

5. **Conclusion**:
- Alkene C has the highest number of hyperconjugative structures (6), which indicates it is the most stable alkene among the given options. Therefore, it will have the highest heat of hydrogenation.

### Final Answer:
**Alkene C has the highest heat of hydrogenation.**

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