Which of the following haloalkanes is most reactive?

Options

A. 1-Chloropropane
B. 1-bromopropane
C. 2-chloropropane
D. 2-bromopropane

Explanation

To determine which haloalkane is the most reactive among the given options, we need to analyze the stability of the carbocations formed during the reaction and the leaving group ability of the halogens involved.

### Step-by-Step Solution:

1. **Identify the Haloalkanes**: The given haloalkanes are:
- Chloropropane (1-chloropropane)
- Bromopropane (1-bromopropane)
- 2-Chloropropane
- 2-Bromopropane

2. **Understand Carbocation Formation**: When a haloalkane reacts, the halogen atom (Cl or Br) leaves, forming a carbocation. The stability of the carbocation is crucial for the reactivity of the haloalkane.
- Primary carbocation: Formed from 1-chloropropane and 1-bromopropane.
- Secondary carbocation: Formed from 2-chloropropane and 2-bromopropane.

3. **Stability of Carbocations**:
- Secondary carbocations are more stable than primary carbocations due to hyperconjugation and inductive effects.
- Therefore, both 2-chloropropane and 2-bromopropane will be more reactive than 1-chloropropane and 1-bromopropane.

4. **Evaluate the Leaving Groups**:
- The leaving group ability is also important. Bromine (Br) is a better leaving group than chlorine (Cl) because it is less electronegative and can stabilize the negative charge better when it leaves.
- Thus, 2-bromopropane will be more reactive than 2-chloropropane.

5. **Conclusion**:
- Among the options, 2-bromopropane is the most reactive haloalkane because it forms a stable secondary carbocation and has bromine as a better leaving group compared to chlorine.

### Final Answer:
**2-Bromopropane is the most reactive haloalkane among the given options.**

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