Chemistry · Isomerism

JEE Advanced 2020 — Paper 1 — Question 18

The Fischer projection of D-erythrose is shown below:

D-Erythrose and its isomers are listed as P, Q, R and S in Column-I.

Choose the correct relationship of P, $\mathrm{Q}, \mathrm{R}$ and S with D-erythrose from Column-II.

Option A:
$\mathrm{P} \rightarrow 2, \mathrm{Q} \rightarrow 3, \mathrm{R} \rightarrow 2, \mathrm{~S} \rightarrow 2$
Option B:
$\mathrm{P} \rightarrow 3, \mathrm{Q} \rightarrow 1, \mathrm{R} \rightarrow 1, \mathrm{~S} \rightarrow 2$
Option C:
$\mathrm{P} \rightarrow 2, \mathrm{Q} \rightarrow 1, \mathrm{R} \rightarrow 1, \mathrm{~S} \rightarrow 3$
Correct
Option D:
$\mathrm{P} \rightarrow 2, \mathrm{Q} \rightarrow 3, \mathrm{R} \rightarrow 3, \mathrm{~S} \rightarrow 1$

Answer: C

Given structure : (2R, 3R)

$P \Rightarrow(2 R, 3 R)$ , so, identical. Hence $P \rightarrow 2$

$Q \Rightarrow(2 S, 3 R)$ , so, Diastereomers. Hence $Q \rightarrow 1$

$R \Rightarrow(2 R, 3 S)$ , so, Diastereomers. Hence $R \rightarrow 1$

$S \Rightarrow(2 S, 3 S)$ , so, Enantiomers. Hence $S \rightarrow 3$

Answer key and solution verified before publishing.

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