Identify the product A and predict the type of reaction:o-Bromoanisole + NaNH2 → A

Q: What is NEET?

NEET is a competitive examination conducted in India. This question is from the 2017 NEET Chemistry paper.

Q: How can I prepare for NEET Chemistry?

To prepare for NEET Chemistry, practice previous year questions (PYQs), understand concepts thoroughly, and solve mock tests regularly. This 2017 question covers Haloalkanes and Haloarenes topic.

Q: What is the difficulty level of this question?

This NEET 2017 Chemistry question has a hard difficulty level and is marked as an important question.

Q: Where can I find more NEET previous year questions?

You can find more NEET previous year questions on AspirantMitraa. Browse by subject, topic, year, and difficulty level to practice effectively.

Question

Identify the product A and predict the type of reaction:o-Bromoanisole + NaNH2 → A

Accepted Answer

Correct Answer: B — m-Anisidine and elimination-addition (benzyne) reactionStep-by-step Solution:o-Bromoanisole reacts with the strong base NaNH2 (sodamide) via the benzyne (elimination-addition) mechanism.Step 1 (Elimination): NaNH2 acts as a strong base and abstracts a proton adjacent to the C–Br bond, causing simultaneous loss of Br− to form a reactive benzyne (aryne) intermediate — specifically 3-methoxybenzyne (with a formal triple bond between C1 and C2 positions).Step 2 (Addition): The NH2− nucleophile adds to the benzyne intermediate. Due to the inductive effect of the –OCH3 group, the partial negative charge on C1 (bearing OCH3) is destabilized, so NH2− preferentially attacks C1. This places –NH2 at C1 and –OCH3 at C1 (same carbon) ... or alternatively, the attack occurs at C2 (meta to OCH3), giving m-anisidine as the predominant product.This reaction is classified as an elimination-addition (benzyne) mechanism, also called cine substitution when the entering group ends up on a carbon different from where the leaving group was.Why other options are incorrect:Option A: The product is m-anisidine (not ortho) because of the regioselectivity of nucleophilic addition to the benzyne intermediate driven by the electronic effects of –OCH3.Option C: Direct substitution implies SNAr (addition-elimination mechanism), which requires strongly electron-withdrawing groups (like –NO2) to activate the ring. –OCH3 is electron-donating, so SNAr does not occur here.Key Concept: Benzyne (aryne) mechanism: occurs when aryl halides react with very strong bases (NaNH2, n-BuLi) in the absence of activating EWG. Proceeds via elimination (forming aryne) then addition (nucleophile attacks the triple bond). The product may have the substituent on a carbon adjacent to the original halide position (cine substitution).

Identify the product A and predict the type of reaction:o-Bromoanisole + NaNH2 → A

Master NEET with Our Test Series

More Questions from Haloalkanes and Haloarenes

Frequently Asked Questions

Identify the product A and predict the type of reaction:o-Bromoanisole + NaNH2 → A

Master NEET with Our Test Series

More Questions from Haloalkanes and Haloarenes

Frequently Asked Questions