Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):
Assertion (A): SN$_2$ reaction of C$_6$H$_5$CH$_2$Br occurs more readily than the SN$_2$ reaction of CH$_3$CH$_2$Br.
Reason (R): The partially bonded unhybridized p-orbital that develops in the trigonal bipyramidal transition state is stabilized by conjugation with the phenyl ring.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. (A) is not correct but (R) is correct
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• D. (A) is correct but (R) is not correct

Answer 1

Answer: (C)

Both (A) and (R) are correct and (R) is the correct explanation of (A)

Answer 2

Explanation:

1. Assertion (A): Correct. - In $C_6H_5CH_2Br$, the $CH_2-Br$ bond is connected to a benzyl group. The phenyl ring allows for stabilization of the transition state via resonance, facilitating the $S_N2$ reaction. This makes the reaction proceed more readily compared to $CH_3CH_2Br$, where no such stabilization exists.

2. Reason (R): Correct. - The unhybridized $p$-orbital formed during the trigonal bipyramidal transition state interacts with the conjugated system of the phenyl ring, providing extra stabilization.

3. Conclusion: Both (A) and (R) are correct, and (R) is the correct explanation for (A).

Final Answer is option (3).