Which among the following alkenes will be most stable :

Options

A. Ethene
B. 2-Methyl but -2 - ene
C. 2,3-Dimethyl-2-butene
D. 2-butene

Answer

To determine which alkene is the most stable among the given options, we can follow these steps:

### Step 1: Identify the Structures of the Alkenes
We have four alkenes to analyze:
1. **Ethene (C2H4)**: CH2=CH2
2. **2-Methylbut-2-ene**: CH3-C(CH3)=CH-CH3
3. **2,3-Dimethylbut-2-ene**: CH3-C(CH3)=C(CH3)-CH3
4. **2-Butene**: CH3-CH=CH-CH3

### Step 2: Understand Alkene Stability
Alkene stability is influenced by the number of alkyl groups attached to the carbon atoms of the double bond. More alkyl substituents generally lead to greater stability. This is due to hyperconjugation and the inductive effect, which stabilize the double bond.

### Step 3: Analyze Each Alkene
- **Ethene**: No alkyl groups attached (least stable).
- **2-Methylbut-2-ene**: Has two alkyl groups attached (more stable than ethene).
- **2,3-Dimethylbut-2-ene**: Has four alkyl groups attached (most stable).
- **2-Butene**: Has two alkyl groups attached (more stable than ethene, but less than 2,3-dimethylbut-2-ene).

### Step 4: Determine the Stability Order
Based on the number of alkyl groups:
1. **2,3-Dimethylbut-2-ene** (most stable)
2. **2-Methylbut-2-ene** (more stable than ethene)
3. **2-Butene** (more stable than ethene)
4. **Ethene** (least stable)

### Conclusion
The most stable alkene among the given options is **2,3-Dimethylbut-2-ene**.

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