JEE Advanced 2022 — Paper 2 — CHEM-II solution

JEE Advanced2022Paper 2CHEM-II

Considering the following reaction sequence, the correct statement(s) is(are)

A
Compounds P and Q are carboxylic acids.
B
Compound S decolorizes bromine water.
C
Compounds P and S react with hydroxylamine to give the corresponding oximes.
D
Compound R reacts with dialkylcadmium to give the corresponding tertiary alcohol.

Solution

P is 4-oxo-4-phenylbutanoic acid (a keto-acid); Q is 4-phenylbutanoic acid; R is the corresponding acyl chloride; S is $α$ -tetralone (a cyclic aryl ketone).

(A) Both P and Q bear a $-$ COOH group; both are carboxylic acids. Correct.

(B) S is a saturated cyclic ketone fused to a benzene ring; it has no isolable C=C double bond outside the aromatic ring (aromatic rings do not decolorize Br $_{2}$ water under normal conditions). Incorrect.

(C) Both P (contains a ketone $-$ CO $-$ ) and S (cyclic ketone) react with NH $_{2}$ OH at the carbonyl carbon to give oximes. Correct.

(D) Dialkylcadmium R' $_{2}$ Cd is a mild nucleophile that converts acyl chlorides to ketones (it stops at the ketone stage and does not add twice). Hence R + R' $_{2}$ Cd gives a ketone, not a tertiary alcohol. Incorrect.

$∴$ (A), (C).

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