Which one of the following compounds will give in the presence of peroxide a product different from that obtainded in the absence peroxide ?

Options

A. 1-butene HCI
B. 1-butene HBr
C. 2-butene HCI
D. 2-butene HBr

Answer

To determine which compound will give a different product in the presence of peroxide compared to the absence of peroxide, we need to analyze the reactions of the given compounds with HCl and HBr.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- 1-butene + HCl
- 1-butene + HBr
- 2-butene + HCl
- 2-butene + HBr

2. **Analyze 1-butene with HCl**:
- **Without Peroxide**: The double bond in 1-butene (CH2=CH-CH2-CH3) will react with HCl. The product will be:
\[ CH3-CH2-CHCl-CH3 \quad (\text{2-chlorobutane}) \]
- **With Peroxide**: In the presence of peroxide, the reaction follows the anti-Markovnikov rule, leading to:
\[ CH2Cl-CH2-CH2-CH3 \quad (\text{1-chlorobutane}) \]
- **Conclusion**: The products are different.

3. **Analyze 1-butene with HBr**:
- **Without Peroxide**: The product will be:
\[ CH3-CH2-CHBr-CH3 \quad (\text{2-bromobutane}) \]
- **With Peroxide**: The reaction will yield:
\[ CH2Br-CH2-CH2-CH3 \quad (\text{1-bromobutane}) \]
- **Conclusion**: The products are different.

4. **Analyze 2-butene with HCl**:
- **Without Peroxide**: The product will be:
\[ CH3-CHCl-CH2-CH3 \quad (\text{2-chlorobutane}) \]
- **With Peroxide**: The product will be the same:
\[ CH3-CHCl-CH2-CH3 \quad (\text{2-chlorobutane}) \]
- **Conclusion**: The products are the same.

5. **Analyze 2-butene with HBr**:
- **Without Peroxide**: The product will be:
\[ CH3-CHBr-CH2-CH3 \quad (\text{2-bromobutane}) \]
- **With Peroxide**: The product will again be:
\[ CH3-CHBr-CH2-CH3 \quad (\text{2-bromobutane}) \]
- **Conclusion**: The products are the same.

### Final Answer:
The compounds that give different products in the presence of peroxide compared to the absence of peroxide are:
- **1-butene + HCl**
- **1-butene + HBr**

Thus, the answer is **1-butene with HCl and HBr**.