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Saturday, 31 October

JEE Main 2023 · ChemistryMultiple choiceDiagram basedHardMulti-step

JEE Main 6 April 2023, Shift 2, Chemistry Q75

Question 75 of 90 in this shift, Chemistry question 15 of 30, Section A.

In the following reaction, 'B' is

The figure, in words

Reactant: 3,4-dimethylcyclohexene (two methyls on the ring, C=C in ring) bearing at the alkene carbon the chain CH2CH2CH(OH)C(CH3)3 (secondary alcohol next to a tert-butyl group); reagent H3O+\mathrm{H_3O^+} giving 'B' (major).
  1. (1)[figure: spiro compound, a cyclohexane ring bearing two methyl groups spiro-fused to a tetrahydrofuran ring that carries a tert-butyl group at the carbon next to O]
  2. (2)[figure: bicyclic ether, cyclohexene ring (C=C at the ring fusion) fused to a six-membered ring containing O, with a tert-butyl group on the carbon next to O; no methyl groups]
  3. (3)[figure: bicyclic, cyclohexane ring with two methyl groups and a C=C at the ring fusion, fused to a cyclopentane ring bearing a tert-butyl group]
  4. (4)[figure: bicyclic decalin-type, ring with two methyl groups and a C=C at the ring fusion, fused to a cyclohexane ring bearing a gem-dimethyl group and a methyl group]Official answer

Official answer

Option 4

NTA final key.

Chapter
Alcohols, Phenols and Ethers
Topic
Alkenes and Alkynes
Idea tested
Carbocation Rearrangements

Same idea in other shifts

Asked 5× in all
  1. 24 Feb 2021, Shift 1 · Q41What is the major product formed by HI on reaction with [figure] ?MediumDiagram basedHas a figure
  2. 24 Feb 2021, Shift 1 · Q44What is the final product (major) ‘A’ in the given reaction ? [figure] →HCl\xrightarrow{\mathrm{HCl}} ‘A’ (major product)MediumDiagram basedHas a figure
  3. 17 Mar 2021, Shift 1 · Q43[reaction drawn: see figure_note] Product “A” in the above chemical reaction is :MediumDiagram basedHas a figure
  4. 2 Sep 2020, Shift 1 · Q41The major product in the following reaction is : 1-methyl-1-vinylcyclopentane (H3C\mathrm{H_3C} and CH=CH2\mathrm{CH=CH_2} on the same ring…HardDiagram 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.