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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedHardMulti-step

JEE Main 27 August 2021, Shift 2, Chemistry Q44

Question 44 of 90 in this shift, Chemistry question 14 of 30, Section A.

Which one of the following is the major product of the given reaction ? [reaction drawn: a fused bicyclic compound - a benzene ring (drawn with an inner circle) bearing NC, fused to a six-membered ring that has CH3\mathrm{CH_3} on the top ring carbon, then a C=O carbon, then a carbon bearing CH3\mathrm{CH_3} (bottom right), then a CH2\mathrm{CH_2} - with reagents (i) 2CH3MgBr\mathrm{2CH_3MgBr} (ii) H3O+\mathrm{H_3O^{+}} (iii) H2SO4\mathrm{H_2SO_4}, heat, giving Major Product]

The figure, in words

Stem and options are fused benzene + six-membered ring line drawings with NC or C(=O)CH3 on the benzene ring and CH3 groups on the other ring.
  1. (1)[structure: benzene ring with NC, fused ring with CH3\mathrm{CH_3} on the top ring carbon which is double-bonded to the next ring carbon bearing CH3\mathrm{CH_3}; then a carbon bearing CH3\mathrm{CH_3} and a CH2\mathrm{CH_2} closing the ring]
  2. (2)[structure: benzene ring with a C(=O)CH3\mathrm{C(=O)CH_3} substituent, fused ring with a top ring carbon bearing CH3\mathrm{CH_3} (single bonds), then a C=C double bond between the next two ring carbons, each bearing CH3\mathrm{CH_3}, then a CH2\mathrm{CH_2}]
  3. (3)[structure: benzene ring with NC, fused ring with a top ring carbon bearing CH3\mathrm{CH_3} (single bonds), then a C=C double bond between the next two ring carbons, each bearing CH3\mathrm{CH_3}, then a CH2\mathrm{CH_2}]
  4. (4)[structure: benzene ring with a C(=O)CH3\mathrm{C(=O)CH_3} substituent, fused ring with CH3\mathrm{CH_3} on the top ring carbon which is double-bonded to the next ring carbon bearing CH3\mathrm{CH_3}; then a carbon bearing CH3\mathrm{CH_3} and a CH2\mathrm{CH_2} closing the ring]Official answer

Official answer

Option 4

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Nucleophilic Addition
Idea tested
Grignard Reagent Addition

Same idea in other shifts

Asked 7× in all
  1. 12 Apr 2023, Shift 1 · Q76In the following reaction [figure: CH3-C(=O)-CH2-CH(CH3)-Br, (i) Mg (ii) H2O\mathrm{H_2O} -> 'A' (Major Product)] A isHardSingle correctHas a figure
  2. 25 Jun 2022, Shift 2 · Q76In the given reaction 2A2\mathrm{A} →(iii) H2O / H+(i) 2 Mg, THF; (ii) Methyl benzoate\xrightarrow[\text{(iii) } \mathrm{H_2O\ /\ H^+}]{\text{(i) 2 Mg, THF; (ii) Methyl benzoate}} [drawn…MediumDiagram basedHas a figure
  3. 26 Jun 2022, Shift 1 · Q75[figure: drawn structure with the label MgBr at its upper end and the label MgBr at its lower end, the two joined by a bracket-shaped…HardOtherHas a figure
  4. 4 Aug 2021, Shift 2 · Q44The major products A and B in the following reaction sequence are [reaction scheme: see figure_note] (Ph = - C6H5\mathrm{C_6H_5})MediumDiagram basedHas a figure
  5. 25 Jul 2021, Shift 2 · Q50A reaction of benzonitrile with one equivalent CH3MgBr\mathrm{CH_3MgBr} followed by hydrolysis produces a yellow liquid "P". The compound "P"…MediumSingle correct
  6. 9 Jan 2020, Shift 1 · Q45Identify (A) in the following reaction sequence : (A) Gives Positive iodoform test…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.