DAT Organic Chemistry: Stereochemistry 2

Question 1

How many stereoisomers are possible for a molecule with 3 stereocenters and no internal symmetry?

Accepted Answer

8

Answer

The maximum number of stereoisomers is 2^n, so 2^3 = 8.

Question 2

Two compounds are enantiomers. Which property differs between them?

Accepted Answer

Direction of plane-polarized light rotation

Answer

Enantiomers rotate plane-polarized light in equal but opposite directions while sharing all other physical properties.

Question 3

A meso compound is best described as:

Accepted Answer

Achiral despite having stereocenters

Answer

A meso compound contains stereocenters but has an internal plane of symmetry, making it achiral.

Question 4

What is the relationship between (2R,3R) and (2S,3R) of the same molecule?

Accepted Answer

Diastereomers

Answer

They differ at one stereocenter but not all, so they are diastereomers.

Question 5

In assigning R/S, which atom gets highest priority?

Accepted Answer

Highest atomic number

Answer

CIP rules rank substituents by atomic number, highest first.

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