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Saturday, 31 October

JEE Main 2022 · ChemistryMultiple choiceDiagram basedHardMulti-step

JEE Main 27 July 2022, Shift 2, Chemistry Q73

Question 73 of 90 in this shift, Chemistry question 13 of 30, Section A.

Major product ‘B’ of the following reaction sequence is : CH3−C(CH3)=CH−CH3\mathrm{CH_3-C(CH_3)=CH-CH_3} →CH3OHBr2\xrightarrow[\mathrm{CH_3OH}]{\mathrm{Br_2}} A →HI\xrightarrow{\mathrm{HI}} B (major product)

The figure, in words

Starting alkene 2-methylbut-2-ene (drawn with CH3 below the C=), treated with Br2/CH3OH to give A then HI to give B.
  1. (1)[figure: CH3−C(CH3)(OH)−CH(Br)−CH3\mathrm{CH_3-C(CH_3)(OH)-CH(Br)-CH_3}]
  2. (2)[figure: CH3−C(CH3)(I)−CH(Br)−CH3\mathrm{CH_3-C(CH_3)(I)-CH(Br)-CH_3}]Official answer
  3. (3)[figure: CH3−C(CH3)(Br)−CH(OH)−CH3\mathrm{CH_3-C(CH_3)(Br)-CH(OH)-CH_3}]
  4. (4)[figure: CH3−C(CH3)(Br)−CH(I)−CH3\mathrm{CH_3-C(CH_3)(Br)-CH(I)-CH_3}]

Official answer

Option 2

NTA final key.

Chapter
Hydrocarbons
Topic
Alkenes and Alkynes
Idea tested
Halohydrin Formation Regiochemistry

Same idea in other shifts

Asked 3× in all
  1. 25 Jun 2022, Shift 2 · Q75Amongst the following, the major product of the given chemical reaction is [drawn: six-membered ring containing one O, with a double bond…HardDiagram basedHas a figure
  2. 31 Aug 2021, Shift 1 · Q44Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Treatment of…MediumAssertion–reason

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.