Question

The major product of the following reaction is : 
(Image shows Benzene reacting with 2-nitropropene in presence of H$_2$SO$_4$) 

• A. A
• B. B
• C. C
• D. D

Hint:

In electrophilic addition to alkenes, the proton from the acid catalyst adds to the double-bonded carbon that results in the formation of the more stable carbocation. Remember to consider the electronic effects of substituents like -NO₂ which can destabilize an adjacent positive charge.

Answer 1

The Correct Option is D

Step 1: Nature of the reaction The reaction takes place in the presence of concentrated $H_2SO_4$, a strong acid. Under these conditions, alkenes undergo electrophilic activation via protonation, and benzene reacts through electrophilic aromatic substitution (Friedel–Crafts type alkylation). Step 2: Protonation of 2-nitropropene 2-Nitropropene has the structure: \[ CH_3-C(NO_2)=CH_2 \] On treatment with $H^+$, protonation occurs at the terminal carbon of the double bond, leading to formation of a more stable secondary carbocation: \[ CH_3-\overset{+}{C}(NO_2)-CH_3 \;\longrightarrow\; CH_3-CH^{+}-CH_2NO_2 \] This carbocation is preferred because:
It is secondary (more stable than primary)
Protonation avoids placing the positive charge directly adjacent to the strongly electron-withdrawing $NO_2$ group
Step 3: Electrophilic attack on benzene The generated carbocation acts as the electrophile and attacks the $\pi$-electron cloud of benzene, forming a sigma complex: \[ C_6H_6 + CH_3-CH^{+}-CH_2NO_2 \;\longrightarrow\; C_6H_5-CH(CH_3)-CH_2NO_2 \] Step 4: Deprotonation and restoration of aromaticity Loss of a proton from the sigma complex restores aromaticity, yielding the final product. Step 5: Identify the product The major product formed is: \[ \boxed{C_6H_5-CH(CH_3)-CH_2NO_2} \] This compound is named: \[ 2-phenyl-1-nitropropane \] Conclusion The structure corresponding to 2-phenyl-1-nitropropane matches option (D).