`CH_(2) = CH - NO_(2) + HBr to P, ` The major product P is

Options

A. `underset(Br)underset(|)(CH_(2)) -CH_(2)-NO_(2)`
B. 'CH_(3)-underset(Br)underset(|)(CH)-NO_(2)`
C. `CH_(2) =underset(Br)underset(|)(C )-NO_(2)`
D. `CH_(2) =CH -Br`

Answer

To determine the major product \( P \) from the reaction of \( CH_2=CH-NO_2 \) with \( HBr \), we can follow these steps:

### Step 1: Identify the Reactants
The reactant is an alkene \( CH_2=CH-NO_2 \) (where \( NO_2 \) is a nitro group attached to the vinyl carbon). The reaction involves the addition of \( HBr \).

### Step 2: Understand the Mechanism of the Reaction
The addition of \( HBr \) to the alkene occurs via an electrophilic addition mechanism. The \( H^+ \) from \( HBr \) will attack the double bond, leading to the formation of a carbocation intermediate.

### Step 3: Formation of Carbocation
When \( H^+ \) attacks the alkene, it can add to either of the carbon atoms involved in the double bond:
1. **Carbocation A**: If \( H^+ \) adds to the terminal carbon (\( CH_2 \)), the carbocation will be formed at the adjacent carbon (\( CH \)).
2. **Carbocation B**: If \( H^+ \) adds to the carbon attached to the \( NO_2 \) group, the carbocation will be formed at the terminal carbon.

### Step 4: Analyze the Stability of Carbocations
- **Carbocation A**: This carbocation is adjacent to the electron-withdrawing \( NO_2 \) group, which destabilizes it.
- **Carbocation B**: This carbocation is further away from the \( NO_2 \) group, making it less destabilized compared to Carbocation A.

### Step 5: Attack of Bromide Ion
After the formation of the carbocation, the bromide ion \( Br^- \) will attack the more stable carbocation:
1. If Carbocation A is formed, the product will be \( CH_2-CH(NO_2)-Br \).
2. If Carbocation B is formed, the product will be \( CH_2Br-CH(NO_2) \).

### Step 6: Determine the Major Product
Since Carbocation B is more stable due to being less affected by the \( NO_2 \) group, the major product \( P \) will be the one derived from Carbocation B:
- The major product \( P \) is \( CH_2Br-CH(NO_2) \).

### Conclusion
The major product \( P \) from the reaction of \( CH_2=CH-NO_2 \) with \( HBr \) is \( CH_2Br-CH(NO_2) \).

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