Chemistry · Hydrocarbons

JEE Main 2024 — 4 April, Shift 2 — Question 63

In the given reaction sequence, identify the the reagents " $A$ " and " $B$ ", respectively.

Option A:
$\mathrm{O}_{3}, \mathrm{Zn} / \mathrm{H}_{2} \mathrm{O}$ and $\mathrm{NaOH}{\text {(alc.) }} / \mathrm{I}_{2}$
Correct
Option B:
$\mathrm{H}_{2} \mathrm{O}, \mathrm{H}^{+}$ and $\mathrm{NaOH}{\text {(alc.) }} / \mathrm{I}_{2}$
Option C:
$\mathrm{H}_{2} \mathrm{O}, \mathrm{H}^{+}$ and $\mathrm{KMnO}_{4}$
Option D:
$\mathrm{O}_{3}, \mathrm{Zn} / \mathrm{H}_{2} \mathrm{O}$ and $\mathrm{KMnO}_{4}$

Answer: A

Step-by-step solution

Step A: The starting compound contains a $\mathrm{C=C}$ double bond, which on reaction gives carbonyl compounds (an aldehyde and a ketone). This transformation is characteristic of reductive ozonolysis, carried out using $\mathrm{O_3/Zn/H_2O}$ .

Step B: In the next step, the methyl ketone group present in the product undergoes the iodoform reaction, forming the corresponding sodium carboxylate. This reaction requires $\mathrm{I_2/NaOH\ (alc.)}$ .

Therefore, the correct reagents are $\mathrm{O_3/Zn/H_2O}$ and $\mathrm{I_2/NaOH\ (alc.)}$ (Option A).

Answer key and solution verified before publishing.

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Exam: JEE Main 2024
Paper: 4 April, Shift 2
Subject: Chemistry
Chapter: Hydrocarbons
Topic: Properties & Uses of Alkenes and Dienes