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Saturday, 31 October

JEE Main 2023 · ChemistryMultiple choiceDiagram basedHardMulti-step

JEE Main 6 April 2023, Shift 2, Chemistry Q77

Question 77 of 90 in this shift, Chemistry question 17 of 30, Section A.

Find out the major product from the following reaction.

The figure, in words

Reactant: 3-methylcyclohex-2-en-1-one (C=O at top, ring C=C, methyl on the alkene carbon). Reagents: 1) MeMgBr/CuI 2) nPrI.
  1. (1)[figure: cyclohexene ring with OH and Me on the same sp3 carbon (HO, Me) and a methyl on the alkene carbon two atoms away: 1,3-dimethylcyclohex-2-en-1-ol]
  2. (2)[figure: cyclohexanone with a propyl group on the carbon alpha to C=O and gem-dimethyl (Me, Me) on the carbon at ring position 5, i.e. 5,5-dimethyl-2-propylcyclohexanone]
  3. (3)[figure: cyclohexanone with a propyl group on the alpha carbon and gem-dimethyl (Me, Me) on the adjacent carbon, i.e. 3,3-dimethyl-2-propylcyclohexanone]Official answer
  4. (4)[figure: cyclohexane ring (no C=O); one ring carbon bears a propyl group and a methyl group, and the neighbouring ring carbon bears two methyl groups (Me, Me)]

Official answer

Option 3

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Nucleophilic Addition
Idea tested
Grignard Addition to Alpha,Beta-Unsaturated Carbonyls

Same idea in other shifts

Asked 2× in all
  1. 25 Jul 2021, Shift 1 · Q43[figure: but-3-en-2-one, CH2=CH-C(=O)-CH3, treated with (i) C2H5MgBr\mathrm{C_2H_5MgBr}, dry ether (ii) H2O\mathrm{H_2O}, HCl giving P (Major…HardSingle correctHas 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.