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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumApplication

JEE Main 31 August 2021, Shift 2, Chemistry Q43

Question 43 of 90 in this shift, Chemistry question 13 of 30, Section A.

For the following sequence of reactions, the correct products are : [benzene ring drawn with alternating double bonds] 1. Br2/Fe/Δ\Delta 2. Mg/dry ether 3. CH3OH\mathrm{CH_3OH} -> Products

The figure, in words

Benzene ring (alternating double bonds) with reagent list 1. Br2/Fe/Δ, 2. Mg/dry ether, 3. CH3OH over an arrow to 'Products'; options are drawn benzene derivatives plus a Mg-containing co-product.
  1. (1)[figure: benzene ring bearing H, + Mg bearing OCH3 and Br]Official answer
  2. (2)[figure: benzene ring bearing OCH3, + HMgBr]
  3. (3)[figure: benzene ring bearing CH3, + Mg bearing OH and Br]
  4. (4)[figure: benzene ring bearing Br, + Mg bearing H and OCH3]

Official answer

Option 1

NTA final key.

Chapter
Haloalkanes and Haloarenes
Topic
Alkanes and Free Radicals
Idea tested
Alkane Synthesis via Grignard Protonation

Same idea in other shifts

Asked 3× in all
  1. 26 Jul 2022, Shift 2 · Q89A 100 mL solution of CH3CH2MgBr\mathrm{CH_3CH_2MgBr} on treatment with methanol produces 2.24 mL of a gas at STP. The weight of gas produced is…EasyNumerical value
  2. 27 Aug 2021, Shift 1 · Q43In the following sequence of reactions the P is : [ring structure with Cl drawn] + Mg →etherdry\xrightarrow[\text{ether}]{\text{dry}} [ A ]…EasyDiagram basedHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.