`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 \( P \) formed from the reaction of \( CH_2=CH-NO_2 \) with \( HBr \), we can follow these steps:

### Step 1: Identify the Reactants
The reactant is a nitro-substituted alkene, specifically \( CH_2=CH-NO_2 \). The double bond is between the two carbon atoms, and there is a nitro group (\( NO_2 \)) attached to one of the carbon atoms.

**Hint:** Recognize the structure of the alkene and the substituents attached to it.

### Step 2: Understand the Nature of the Nitro Group
The nitro group (\( NO_2 \)) is an electron-withdrawing group due to its -I (inductive) and -M (mesomeric) effects. This means it will pull electron density away from the double bond, making the carbon atom adjacent to it more positive.

**Hint:** Consider how electron-withdrawing groups affect the electron density in the molecule.

### Step 3: Electrophilic Addition of HBr
When \( HBr \) is added to the alkene, it dissociates into \( H^+ \) and \( Br^- \). The double bond acts as a nucleophile and will attack the \( H^+ \) ion. The more positive carbon (the one adjacent to the \( NO_2 \) group) will preferentially bond with \( H^+ \) due to the electron-withdrawing effect of the \( NO_2 \) group.

**Hint:** Identify which carbon will be protonated based on the stability of the resulting carbocation.

### Step 4: Formation of the Carbocation
After the addition of \( H^+ \), a carbocation is formed on the carbon that is less substituted (the one that is not attached to the \( NO_2 \)). The other carbon will then carry a positive charge.

**Hint:** Visualize the transition state and the stability of the carbocation formed.

### Step 5: Nucleophilic Attack by Bromide Ion
The bromide ion (\( Br^- \)) will then attack the positively charged carbon atom. This results in the formation of the product.

**Hint:** Remember that the nucleophile attacks the positively charged carbon.

### Step 6: Write the Major Product
The final product \( P \) will be \( CH_2Br-CH_2-NO_2 \). This product is formed by the addition of \( H \) to the carbon adjacent to the \( NO_2 \) group and \( Br \) to the other carbon.

**Hint:** Ensure to correctly place the substituents in the final product structure.

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

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