NEETChemistryHaloalkanes and Haloarenes
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Bromobenzene does not yield -bromophenylacetic acid when subjected to the reaction sequence of KCN, followed by acidic hydrolysis, and then Br ₂ /Red P. Reason (R): Aryl halides are highly unreactive towards nucleophilic substitution reactions under normal conditions. In the light of the above stat
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A).
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A).
- C(A) is correct but (R) is not correct.
- D(A) is not correct but (R) is correct.
Correct answer
A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
Step-by-step solution
The Assertion is correct. The proposed reaction sequence begins with the treatment of bromobenzene with KCN. However, this first step fails because the C-Br bond in bromobenzene acquires partial double bond character due to resonance, making it highly resistant to nucleophilic substitution by the cyanide ion under normal conditions. Since the first step (formation of benzonitrile) does not occur, the subsequent steps cannot proceed to form -bromophenylacetic acid. The Reason is also correct and provides the exact e