Stability of iso-butylene can be best explained by

Options

A. inductive effect
B. Mesomeric effect
C. hyperconjugative effect
D. steric effect.

Explanation

To determine the stability of isobutylene, we need to analyze the contributing factors that affect its stability. Here’s a step-by-step breakdown of the reasoning:

### Step 1: Understand the Structure of Isobutylene
Isobutylene, also known as 2-methylpropene, has the following structure:
- It consists of four carbon atoms with a double bond between the first and second carbon atoms.
- The structure can be represented as:
\[ \text{CH}_2=C(\text{CH}_3)\text{CH}_3 \]

### Step 2: Identify the Possible Effects on Stability
The stability of isobutylene can be influenced by several electronic effects:
1. **Inductive Effect**
2. **Mesomeric Effect (Resonance)**
3. **Hyperconjugative Effect**
4. **Steric Effect**

### Step 3: Analyze Each Effect
- **Mesomeric Effect:**
- This effect involves resonance stabilization, which occurs when there are lone pairs or multiple bonds adjacent to the double bond. In the case of isobutylene, there is only one double bond and no adjacent lone pairs or additional double bonds to facilitate resonance. Therefore, the mesomeric effect is not significant here.

- **Inductive Effect:**
- The inductive effect involves the shifting of electrons through sigma bonds due to electronegativity differences. In isobutylene, the methyl groups (−CH₃) are electron-donating, which can destabilize the double bond by increasing electron density. However, this effect does not significantly enhance stability.

- **Hyperconjugative Effect:**
- Hyperconjugation involves the interaction of the σ-bonds (C-H) with the π-bond (C=C) of the double bond. In isobutylene, there are six alpha hydrogens (hydrogens attached to the carbons adjacent to the double bond) that can participate in hyperconjugation. This interaction stabilizes the double bond significantly.

- **Steric Effect:**
- The steric effect refers to the repulsion between atoms that are in close proximity. While the methyl groups can introduce some steric hindrance, this effect is relatively minor compared to the stabilizing effect of hyperconjugation.

### Step 4: Conclusion
After analyzing the effects, we find that the **hyperconjugative effect** is the most significant contributor to the stability of isobutylene. The presence of multiple alpha hydrogens allows for extensive hyperconjugation, which stabilizes the molecule.

### Final Answer
The stability of isobutylene can be best explained by the **hyperconjugative effect**.