which alkene does not follow Anti-Markownikoff's addition rule

Options

A. 2 - butene
B. 1 - butene
C. 2 - pentene
D. 2 - hexene

Answer

To determine which alkene does not follow the Anti-Markovnikov addition rule, we first need to understand the concepts of Markovnikov and Anti-Markovnikov addition.

### Step-by-Step Solution:

1. **Understand the Rules**:
- **Markovnikov's Rule**: When HX (where X is a halogen) is added to an unsymmetrical alkene, the hydrogen atom attaches to the carbon with more hydrogen atoms, while the halogen attaches to the carbon with fewer hydrogen atoms.
- **Anti-Markovnikov's Rule**: In contrast, when the addition occurs via a radical mechanism, the halogen attaches to the carbon with more hydrogen atoms, and the hydrogen attaches to the carbon with fewer hydrogen atoms.

2. **Identify the Alkenes**:
We are given four alkenes. Let's identify them:
- But-2-ene
- But-1-ene
- Pent-2-ene
- Hex-2-ene

3. **Determine Symmetry**:
- **But-2-ene**: This is symmetrical (the same groups on both sides of the double bond).
- **But-1-ene**: This is unsymmetrical (different groups on each side of the double bond).
- **Pent-2-ene**: This is unsymmetrical (different groups on each side of the double bond).
- **Hex-2-ene**: This is also unsymmetrical (different groups on each side of the double bond).

4. **Conclusion**:
Since Anti-Markovnikov's addition rule applies to unsymmetrical alkenes, and But-2-ene is symmetrical, it does not follow the Anti-Markovnikov addition rule. Thus, the correct answer is **But-2-ene**.

### Final Answer:
**But-2-ene does not follow Anti-Markovnikov's addition rule.**