Q8 · CSIR-NET Chemistry, June 2015
Paper: CSIR-NET June 2015 · Subject: Organic Chemistry · Chapter: General Organic Chemistry · Topic: Stereochemistry R S E Z · Marks: 2 · Difficulty: Medium
Identify two enantiomers among the following compounds
(a)
A and B
A and B(b)
A and C
A and C(c)
B and D
B and D(d)
C and D
C and DAnswer
Answer (as printed): D
Explanation
Enantiomers are non-superimposable mirror images. All four structures are 2,3-dibromobutane. Assigning CIP descriptors gives: A = (2S,3R) meso; B = (2R,3S) meso, identical to A; C = (2R,3R); D = (2S,3S). Only C and D are a non-superimposable mirror-image pair, so they are the enantiomers (d).
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