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Friday, 9 October

JEE Main 2020 · ChemistryMultiple choiceDiagram basedHardMulti-step

JEE Main 2 September 2020, Shift 1, Chemistry Q43

Question 43 of 75 in this shift, Chemistry question 18 of 25.

The major aromatic product C in the following reaction sequence will be : 2-methyl-2H-chromene (benzene ring fused to a pyran ring with O, a CH(CH3) next to O and a CH=CH in the ring) →ΔHBr (excess)\xrightarrow[\Delta]{\mathrm{HBr\ (excess)}} A →(ii) H+(i) KOH (Alc.)\xrightarrow[\text{(ii) }\mathrm{H^+}]{\text{(i) KOH (Alc.)}} B →O3, Zn/H3O+\xrightarrow{\mathrm{O_3},\ \mathrm{Zn/H_3O^+}} C

The figure, in words

Starting material drawn as a bicyclic 2-methyl-2H-chromene (benzene fused to a six-membered ring containing O, with a methyl-bearing carbon next to O and a C=C); reaction arrows: HBr (excess), heat gives A; (i) KOH (Alc.), (ii) H+ gives B; O3, Zn/H3O+ gives C.
  1. (1)[figure: benzene ring with Br and CHO on adjacent (ortho) carbons]
  2. (2)[figure: benzene ring with Br and CH2CO2H\mathrm{CH_2CO_2H} on adjacent (ortho) carbons]
  3. (3)[figure: benzene ring with OH and CHO on adjacent (ortho) carbons]Official answer
  4. (4)[figure: benzene ring with OH and CH2CO2H\mathrm{CH_2CO_2H} on adjacent (ortho) carbons]

Official answer

Option 3

NTA final key (Sep 2020).

Chapter
Haloalkanes and Haloarenes
Topic
Ethers
Idea tested
Excess Hot HI Cleavage

Same topic in other shifts

All Ethers questions
  1. 6 Apr 2026, Shift 2 · Q66Consider the following reaction. [figure: benzyl phenyl ether, C6H5−O−CH2−C6H5\mathrm{C_6H_5{-}O{-}CH_2{-}C_6H_5}] ++ HI →\rightarrow Product…EasyTwo statementsHas a figure
  2. 4 Apr 2025, Shift 2 · Q68A toxic compound "A" when reacted with NaCN in aqueous acidic medium yields an edible cooking component and food preservative "B". "B" is…HardSingle correct
  3. 8 Apr 2025, Shift 2 · Q67Which one of the following reactions will not lead to the desired ether formation in major proportion ? (iso-Bu ⇒ isobutyl, sec-Bu ⇒…MediumSingle correctHas a figure
  4. 29 Jan 2024, Shift 1 · Q77The major product (P) in the following reaction isMediumDiagram 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 42 of the 174 JEE Main shifts held from 2017 to 2026.