JEE Advanced 2022 · Paper 1 · Chemistry Q14

ChemistryMultiple correct+4 / -2Question 50 of 54

Considering the following reaction sequence,

the correct option(s) is(are)

P =

\ce{H2}

/Pd, ethanol; R =

\ce{NaNO2}

/HCl; U = 1.

\ce{H3PO2}

\ce{KMnO4}

-KOH, heat

P = Sn/HCl; R =

\ce{HNO2}

; S = 4-methylbenzenediazonium chloride (structure)

S = 4-methylbenzenediazonium chloride; T = 4-methylphenol (p-cresol); U = 1.

\ce{CH3CH2OH}

\ce{KMnO4}

-KOH, heat

Q = 4-nitrobenzoic acid (structure); R =

\ce{H2}

/Pd, ethanol; T = 4-methylphenol (structure)

Answer and worked solution

Official answer: A, B, C

The sequence.

Q: reducing 4-nitrotoluene ( $\ce{H2}$ /Pd or Sn/HCl) gives p-toluidine.
S: diazotisation ( $\ce{NaNO2}$ /HCl, i.e. $\ce{HNO2}$ ) gives 4-methylbenzenediazonium chloride.
T: warming S with water gives p-cresol.
U: to get benzoic acid, first remove the $\ce{N2+}$ group, then oxidise the methyl group with hot alkaline $\ce{KMnO4}$ . Both $\ce{H3PO2}$ and ethanol reduce $\ce{ArN2+}$ to ArH, giving toluene.

The options.

JEE Advanced 2022 · Paper 1, Chemistry question 14