The correct statement(s) about the following reaction sequence is(are) $$\text{Cumene }(\mathrm{C}_{9}\mathrm{H}_{12}) \xrightarrow[\text{ii) }\mathrm{H}_{3}\mathrm{O}^{+}]{\text{i) }\mathrm{O}_{2}} \mathbf{P} \xrightarrow{\mathrm{CHCl}_{3}/\mathrm{NaOH}} \mathbf{Q}\text{ (major) }+\mathbf{R}\text{ (minor)}$$ $$\mathbf{Q} \xrightarrow[\mathrm{PhCH}_{2}\mathrm{Br}]{\mathrm{NaOH}} \mathbf{S}$$

(B) Q gives dark violet coloration with 1% aqueous $\mathrm{FeCl}_{3}$ solution; (C) S gives yellow precipitate with 2, 4-dinitrophenylhydrazine

(A) $\mathbf{R}$ is steam volatile

(D) S gives dark violet coloration with 1% aqueous $\mathrm{FeCl}_{3}$ solution

JEE Advanced · 2016 · 22 May 2016 · Paper 1 · Alcohols Phenols and Ethers

WhatsApp Email

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

Cumene (C_{9} H_{12}) i) O_{2} ii) H_{3} O^{+} P CHCl_{3} / NaOH Q (major) + R (minor)

Q NaOH PhCH_{2} Br S

(A) $R$ is steam volatile
(B)Q gives dark violet coloration with 1% aqueous $FeCl_{3}$ solution✓ Correct
(C)S gives yellow precipitate with 2, 4-dinitrophenylhydrazine✓ Correct
(D)S gives dark violet coloration with 1% aqueous $FeCl_{3}$ solution

Answer: (B), (C)

Solution

Cumene undergoes autoxidation followed by acid-catalyzed rearrangement to give phenol (P). Reimer-Tiemann reaction on phenol gives salicylaldehyde (Q, major, ortho-hydroxybenzaldehyde) and p-hydroxybenzaldehyde (R, minor). Q has intramolecular H-bonding, making it steam volatile, not R. Q is a phenol and gives violet color with

FeCl_{3}

(B correct). Q reacts with benzyl bromide to give benzyl salicylate (S), which has an aldehyde group and gives yellow precipitate with 2,4-DNP (C correct). S has the phenolic OH protected as benzyl ether, so no

FeCl_{3}

test (D incorrect).

JEE Advanced · 2016 · 22 May 2016 · Paper 1 · One or more correct options

Practise more: all JEE Advanced PYQs on Alcohols Phenols and Ethers →

JEE Advanced · 2016 · 22 May 2016 · Paper 1 · Alcohols Phenols and Ethers

Solution

More JEE Advanced questions on Alcohols Phenols and Ethers