The product formed when but-1-ene is subjected to HBr in the presence of peroxide is

Options

A. 1-bromobutane
B. 2-bromobutane
C. 1, 1-dibromobutane
D. 1, 2-dibromobutane.

Answer

To solve the problem of what product is formed when but-1-ene is subjected to HBr in the presence of peroxide, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactant is but-1-ene (C4H8), which has the structure CH2=CH-CH2-CH3.

2. **Understand the Reaction Conditions**:
- The reaction involves HBr (hydrobromic acid) and is performed in the presence of peroxides.

3. **Recall the Mechanism**:
- The presence of peroxides leads to a free radical mechanism that follows the anti-Markovnikov rule. This means that the bromine (Br) will add to the carbon atom that has more hydrogen atoms, rather than the one with more alkyl substituents.

4. **Apply the Anti-Markovnikov Rule**:
- In but-1-ene, the double bond is between the first and second carbon atoms (C1 and C2).
- According to the anti-Markovnikov rule, the bromine will attach to the carbon with more hydrogen atoms (C1), and the hydrogen will attach to the carbon with fewer hydrogen atoms (C2).

5. **Draw the Product**:
- The product will have Br attached to C1 and H attached to C2. Therefore, the structure of the product will be:
- C1: CH2Br
- C2: CH
- C3: CH2
- C4: CH3
- The complete structure of the product is CH2Br-CH2-CH2-CH3.

6. **Name the Product**:
- The product formed is 1-bromobutane.

### Final Answer:
The product formed when but-1-ene is subjected to HBr in the presence of peroxide is **1-bromobutane**.