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Saturday, 31 October

JEE Main 2024 · ChemistryMultiple choiceSingle correctEasyApplication

JEE Main 9 April 2024, Shift 1, Chemistry Q76

Question 76 of 90 in this shift, Chemistry question 16 of 30, Section A.

Identify the product A and product B in the following set of reactions. [figure: CH3−CH=CH2\mathrm{CH_3-CH=CH_2} →H2O, H+\xrightarrow{\mathrm{H_2O,\ H^+}} major Product A; CH3−CH=CH2\mathrm{CH_3-CH=CH_2} →H2O, H2O2, O‾H(BH3)2\xrightarrow[\mathrm{H_2O,\ H_2O_2,\ \overline{O}H}]{\mathrm{(BH_3)_2}} major Product B]

The figure, in words

Propene with two reaction paths: H2O/H+ gives product A; (BH3)2 then H2O, H2O2, OH- gives product B.
  1. (1)A - CH3CH2CH2−OH\mathrm{CH_3CH_2CH_2-OH} B - CH3CH2CH2−OH\mathrm{CH_3CH_2CH_2-OH}
  2. (2)A - CH3−CH(OH)−CH3\mathrm{CH_3-CH(OH)-CH_3} B - CH3CH2CH2−OH\mathrm{CH_3CH_2CH_2-OH}Official answer
  3. (3)A - CH3CH2CH2−OH\mathrm{CH_3CH_2CH_2-OH} B - CH3CH(OH)−CH3\mathrm{CH_3CH(OH)-CH_3}
  4. (4)A - CH3CH2CH3\mathrm{CH_3CH_2CH_3} B - CH3CH2CH3\mathrm{CH_3CH_2CH_3}

Official answer

Option 2

NTA final key.

Chapter
Alcohols, Phenols and Ethers
Topic
Alkenes and Alkynes
Idea tested
Hydroboration-Oxidation

Same idea in other shifts

Asked 6× in all
  1. 4 Apr 2024, Shift 2 · Q79CH3−CH2−CH2−Br+NaOH→C2H5OH\mathrm{CH_3-CH_2-CH_2-Br + NaOH \xrightarrow{C_2H_5OH}} Product 'A' Product A →H2O/H+\xrightarrow{\mathrm{H_2O/H^+}} Product "B" Product A…EasySingle correct
  2. 10 Apr 2023, Shift 2 · Q75Incorrect method of preparation for alcohols from the following is:EasySingle correct
  3. 15 Apr 2023, Shift 1 · Q76The product formed in the following multistep reaction is : CH3−CH=CH2\mathrm{CH_3-CH=CH_2}…MediumOtherHas a figure
  4. 24 Jun 2022, Shift 2 · Q75Which of the following reagents / reactions will convert 'A' to 'B'?MediumSingle correctHas a figure
  5. 8 Jan 2020, Shift 2 · Q45The major product [B] in the following sequence of reactions is :…MediumDiagram 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.