50.3k views
0 votes
Assertion: p-O₂N - C₆H₅COCH₃ is prepared by Friedel Crafts acylation of nitrobenzene.

Reason: Nitrobenzene easily undergoes electrophilic substitution reaction.

a. Both A and R are true and R is the correct explanation of A
b. Both A and R are true but R is not correct explanation of A
c. A is true but R is false
d. A and R are false

1 Answer

3 votes

Final answer:

The synthesis of p-nitroacetophenone via Friedel-Crafts acylation of nitrobenzene is indeed possible, but the presence of a nitro group typically directs the acylation to the meta position, making the assertion and reasoning in the question false.

Step-by-step explanation:

The student's question relates to the preparation of p-nitroacetophenone via the Friedel-Crafts acylation of nitrobenzene. To address the assertion, p-nitroacetophenone (p-O₂N-C₆H₄COCH₃) can indeed be synthesized by a Friedel-Crafts acylation reaction. This involves the introduction of an acyl group onto the benzene ring of nitrobenzene in the presence of a Lewis acid catalyst, typically aluminum chloride (AlCl₃). However, nitro groups are strongly deactivating towards electrophilic aromatic substitution reactions, including Friedel-Crafts acylation, and direct this reaction to the meta position rather than the ortho or para positions.

Contrary to the assertion, it is more challenging to obtain para-substituted product directly from nitration, due to the electron-withdrawing nature of the nitro group. As such, if the assertion implies that the direct acylation leads to the para product, it would not align with the typical reactivity of nitro-substituted benzene rings in Friedel-Crafts reactions. Therefore, the student's choice, stating that both the assertion and the reasoning are false, appears to be correct in this context.

User Sabyasachi
by
8.8k points