Learn

Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumApplication

JEE Main 31 August 2021, Shift 2, Chemistry Q45

Question 45 of 90 in this shift, Chemistry question 15 of 30, Section A.

The structures of A and B formed in the following reaction are : [Ph = −C6H5-\mathrm{C_6H_5}] [benzene ring (with inner circle) + a five-membered cyclic anhydride drawn as a ring containing O with two C=O groups] -> (AlCl3_3(2 eq)) A -> (Zn/Hg, HCl) B

The figure, in words

Benzene ring plus a cyclic five-membered anhydride (ring O with two C=O) with AlCl3 (2 eq) over arrow to A, then Zn/Hg over HCl to B. Options are line-drawn structures of A and B.
  1. (1)A = Ph-C(=O)-CH2-CH2-C(=O)-OH (line drawing: Ph attached to C=O, then two CH2, then COOH), B = Ph-CH2-CH2-CH2-C(=O)-OH (line drawing)Official answer
  2. (2)A = Ph-C(=O)-CH2-CH2-C(=O)-OH (line drawing), B = Ph-CH2-CH2-CH2-CH2-OH (line drawing, chain ending in OH)
  3. (3)A = Ph-C(=O)-CH2-CH3 (line drawing), B = Ph-CH(OH)-CH2-CH3 (line drawing)
  4. (4)A = Ph-C(=O)-CH2-CH3 (line drawing), B = Ph-CH2-CH2-CH3 (line drawing)

Official answer

Option 1

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Aromatic Hydrocarbons
Idea tested
Friedel-Crafts Acylation and Acylium Ion

Same idea in other shifts

Asked 4× in all
  1. 4 Apr 2024, Shift 1 · Q89The number of the correct reaction(s) among the following is ________. (A) [benzene + benzoyl chloride (C6H5COCl\mathrm{C_6H_5COCl}),…MediumNumerical valueHas a figure
  2. 5 Apr 2024, Shift 2 · Q75Identify A and B in the given chemical reaction sequence : Benzene + succinic anhydride (cyclic five-membered anhydride)…MediumDiagram basedHas a figure
  3. 31 Jan 2024, Shift 2 · Q77Identify major product 'P' formed in the following reaction. [reaction: benzene + benzoyl chloride (C6_6H5_5COCl) --(Anhydrous…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.