JEE Advanced 2022 · Paper 2 · Chemistry Q7

ChemistryInteger+3 / -1Question 43 of 54

The number of $-\mathrm{CH_2}-$ (methylene) groups in the product formed from the following reaction sequence is ________.

Your answer

Answer and worked solution

Official answer: 0

Step by step.

Ozonolysis of oct-4-ene ( $\ce{O3}$ , Zn/ $\ce{H2O}$ ) gives 2 molecules of butanal.
$\ce{KMnO4}$ oxidises it to butanoic acid.
Kolbe electrolysis of sodium butanoate couples two propyl radicals: $\ce{2C3H7COO- -> C6H14 + 2CO2}$ , giving n-hexane.
$\ce{Cr2O3}$ at 770 K and 20 atm aromatises hexane to benzene.

Benzene has 0 $\ce{-CH2-}$ groups.

JEE Advanced 2022 · Paper 2, Chemistry question 7