JEE Advanced 2016 · Paper 1 · Chemistry Q31

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ChemistryMultiple correct+4 / -2Question 31 of 54

The correct statement(s) about the following reaction sequence is(are)

$\text{Cumene }(\ce{C9H12})\xrightarrow[\text{ii) }\ce{H3O+}]{\text{i) }\ce{O2}}\mathbf P\xrightarrow{\ce{CHCl3/NaOH}}\mathbf Q\text{ (major)}+\mathbf R\text{ (minor)}$
$\mathbf Q\xrightarrow[\ce{PhCH2Br}]{\ce{NaOH}}\mathbf S$

\mathbf R

is steam volatile

\mathbf Q

gives dark violet coloration with 1% aqueous

\ce{FeCl3}

solution

\mathbf S

gives yellow precipitate with 2,4-dinitrophenylhydrazine

\mathbf S

gives dark violet coloration with 1% aqueous

\ce{FeCl3}

solution

Answer and worked solution

Official answer: B, C

Identify the compounds.

P is phenol (cumene hydroperoxide process).
Reimer-Tiemann gives Q, salicylaldehyde (ortho, major), and R, p-hydroxybenzaldehyde (para, minor).
Williamson etherification of Q gives S, 2-(benzyloxy)benzaldehyde.

Check the statements.

(A) R has intermolecular H-bonding and is not steam volatile; it is Q that is steam volatile. False.
(B) Q has a free phenolic OH, so it gives a violet colour with neutral $\ce{FeCl3}$ . True.
(C) S still has the CHO group, so it gives a yellow/orange 2,4-DNP derivative. True.
(D) S has no free phenol. False.

(B), (C)

Topics:Phenols Named reactions

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JEE Advanced 2016 · Paper 1, Chemistry question 31