DAT Organic Chemistry: Stereochemistry 3

Question 1

When the lowest priority group points toward the viewer, the apparent rotation direction must be:

Accepted Answer

Reversed

Answer

If the lowest priority group faces you, you reverse the assigned rotation to get the correct R/S.

Question 2

Which of the following is achiral?

Accepted Answer

Glycine (aminoacetic acid)

Answer

Glycine's alpha carbon bears two hydrogens, so it has no stereocenter and is achiral.

Question 3

Diastereomers differ from enantiomers because diastereomers:

Accepted Answer

Have different physical properties

Answer

Diastereomers are not mirror images and therefore have different physical properties.

Question 4

A compound with specific rotation [α] = 0 but containing stereocenters is most likely:

Accepted Answer

A meso compound or racemate

Answer

Zero rotation with stereocenters points to either a meso compound or a racemic mixture.

Question 5

Converting a Fischer projection: horizontal lines represent bonds pointing:

Accepted Answer

Toward the viewer

Answer

In a Fischer projection, horizontal bonds point toward the viewer and vertical bonds point away.

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