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Saturday, 31 October

JEE Main 2023 · ChemistryMultiple choiceSingle correctMediumApplication

JEE Main 12 April 2023, Shift 1, Chemistry Q77

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

[figure: Me−C(=O)\mathrm{Me-C(=O)}-(zig-zag chain)-C(=O)−CH3\mathrm{C(=O)-CH_3} --OEt−\mathrm{OEt^-}, Δ\Delta--> 'A' major Product] A in the above reaction is:

The figure, in words

Reactant: diketone Me-C(=O)-(zig-zag carbon chain)-C(=O)-CH3, with OEt-, heat giving 'A' (major product).
  1. (1)[figure: Me−C(=O)\mathrm{Me-C(=O)}-(zig-zag chain)-C(Me)=CH−C(=O)\mathrm{C(Me)=CH-C(=O)}-(zig-zag chain)-C(=O)−CH3\mathrm{C(=O)-CH_3}]
  2. (2)[figure: Me−C(=O)\mathrm{Me-C(=O)}-(zig-zag chain)-C(Me)=C\mathrm{C(Me)=C} where the alkene carbon bears C(=O)−CH3\mathrm{C(=O)-CH_3} and a further chain ending in C(=O)−CH3\mathrm{C(=O)-CH_3}]
  3. (3)[figure: cyclopentene ring with Me on one alkene carbon and C(=O)−CH3\mathrm{C(=O)-CH_3} on the other alkene carbon]Official answer
  4. (4)[figure: seven-membered ring, cycloheptenone with C=O and a Me-substituted alkene carbon (C=C adjacent to C=O)]

Official answer

Option 3

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Aldol and Cannizzaro
Idea tested
Intramolecular Aldol

Same idea in other shifts

Asked 5× in all
  1. 8 Apr 2025, Shift 2 · Q68When [structure: CH3C(=O)CH2CH2CH2CH2CHO\mathrm{CH_3C(=O)CH_2CH_2CH_2CH_2CHO}, a skeletal zigzag chain with a methyl ketone at one end and an aldehyde (C=O…MediumSingle correctHas a figure
  2. 30 Jun 2022, Shift 1 · Q76Which among the following will be the major product of the given reaction ? [structure: skeletal chain: a terminal bond to a C=O carbon (O…MediumDiagram basedHas a figure
  3. 26 Feb 2021, Shift 2 · Q44Identify A in the given chemical reaction. [structure drawn: benzene ring with two adjacent CH2CH2CHO\mathrm{CH_2CH_2CHO} substituents]…MediumDiagram basedHas a figure
  4. 9 Jan 2020, Shift 2 · Q44In the following reaction A is : A…MediumSingle 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.