JEE Main 2022 · 24 Jun · Shift 2 · Chemistry Q75

← JEE Main 2022 · 24 Jun · Shift 2

ChemistrySingle correct+4 / -1Question 75 of 90

Which of the following reagents / reactions will convert 'A' to 'B'?

A, 1-methyl-4-methylenecyclohexane (ring C=CH2 with a CH3 at the para carbon), is converted to B, 4-methylcyclohexane-1-carbaldehyde.

PCC oxidation

Ozonolysis

\mathrm{BH_3}

\mathrm{H_2O_2/{}^-OH}

followed by PCC oxidation

HBr, hydrolysis followed by oxidation by

\mathrm{K_2Cr_2O_7}

Answer and worked solution

Official answer: C

Need. The exocyclic $\mathrm{=CH_2}$ must become $\mathrm{CHO}$ on the ring carbon, one carbon kept.

Hydroboration-oxidation adds water anti-Markovnikov, giving the primary alcohol $\mathrm{CH_2OH}$ on the ring carbon. PCC then oxidises it to the aldehyde B. (Ozonolysis would cut off the CH₂ and give a ketone.)

(C)

Topics:Alkenes Alcohols Oxidation and reduction

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JEE Main 2022 · 24 Jun · Shift 2, Chemistry question 75