A tertiary alcohol $\mathbf{H}$ upon acid catalysed dehydration gives a product I. Ozonolysis of I leads to compounds J and K. Compound J upon reaction with KOH gives benzyl alcohol and a compound $\mathbf{L}$, whereas $\mathbf{K}$ on reaction with KOH gives only $\mathbf{M}$. (see structure of M) The structures of compounds $\mathbf{J}$, $\mathbf{K}$ and $\mathbf{L}$, respectively, are

(D) $\mathrm{PhCHO}$, $\mathrm{PhCOCH}_{3}$ and $\mathrm{PhCOO}^{-}\mathrm{K}^{+}$

(A) $\mathrm{PhCOCH}_{3}$, $\mathrm{PhCH}_{2}\mathrm{COCH}_{3}$ and $\mathrm{PhCH}_{2}\mathrm{COO}^{-}\mathrm{K}^{+}$

(B) $\mathrm{PhCHO}$, $\mathrm{PhCH}_{2}\mathrm{CHO}$ and $\mathrm{PhCOO}^{-}\mathrm{K}^{+}$

(C) $\mathrm{PhCOCH}_{3}$, $\mathrm{PhCH}_{2}\mathrm{CHO}$ and $\mathrm{CH}_{3}\mathrm{COO}^{-}\mathrm{K}^{+}$

JEE Advanced · 2008 · 13 Apr 2008 · Paper 2 · Aldehydes Ketones and Carboxylic Acids

WhatsApp Email

A tertiary alcohol

H

upon acid catalysed dehydration gives a product I. Ozonolysis of I leads to compounds J and K. Compound J upon reaction with KOH gives benzyl alcohol and a compound

L

, whereas

K

on reaction with KOH gives only

M

.
(see structure of M)

The structures of compounds

J

K

and

L

, respectively, are

(A) $PhCOCH_{3}$ , $PhCH_{2} COCH_{3}$ and $PhCH_{2} COO^{-} K^{+}$
(B) $PhCHO$ , $PhCH_{2} CHO$ and $PhCOO^{-} K^{+}$
(C) $PhCOCH_{3}$ , $PhCH_{2} CHO$ and $CH_{3} COO^{-} K^{+}$
(D) $PhCHO$ , $PhCOCH_{3}$ and $PhCOO^{-} K^{+}$ ✓ Correct

Answer: (D)

Solution

From the reaction sequence: J undergoes Cannizzaro reaction with KOH to give benzyl alcohol and L, which means J must be an aldehyde without α-hydrogen (benzaldehyde, PhCHO). K reacts with KOH to give only M (acetophenone derivative), so K must be acetophenone (PhCOCH₃). In the Cannizzaro reaction, benzaldehyde is oxidized to benzoate (L = PhCOO⁻K⁺) and reduced to benzyl alcohol. Therefore, J = PhCHO, K = PhCOCH₃, and L = PhCOO⁻K⁺.

JEE Advanced · 2008 · 13 Apr 2008 · Paper 2 · Single correct option

Practise more: all JEE Advanced PYQs on Aldehydes Ketones and Carboxylic Acids →

JEE Advanced · 2008 · 13 Apr 2008 · Paper 2 · Aldehydes Ketones and Carboxylic Acids

Solution

More JEE Advanced questions on Aldehydes Ketones and Carboxylic Acids