Quiz - Stereoisomers | Stereoisomers

1

What is the definition of a chiral compound?

A superimposable object on its mirror image

A molecule with a carbon atom with 4 different substituents

A molecule with a plan of symmetry

A non-superimposable object on its mirror image

A chiral molecule is a molecule that is not superimposable on its mirror image

2

Which of the following statements is incorrect?

The specific rotation of 2 diastereomers has a different absolute value

(+) in front of a chiral compound means that its absolute configuration is R

A racemic mixture of a chiral compound contains equal amount of (+) and (-) compound

The (+) and (-) stereoisomer of the same chiral compound will rotate polarized light equally but in opposite directions

​​​​​​​(+) in front of a chiral compound means that its specific rotation ​​​​​​​[α]D is positive
When [α]D > 0°, the plane-polarized light is rotated clockwise ⇒ the solution is said to be dextrorotary

3

How many chiral centers does the 2,4-dibromo-1,1,4-trimethylcyclohexane have?

0

1

2

3 or +

Chiral center: atom connected to 4 different substituents
​​​​​​​They are sometimes marked with an asterick

4

Which of the following compound is chiral?

1-bromobutane

2-bromobutane

2-bromo-2-methylbutane

3-bromopentane

2-bromobutane has 1 stereocenter ⇒ this molecule is chiral
The other molecules do not have a stereocenter ⇒ they are achiral

5

Which of the following compound is meso?

cis-1,3-dimethylcyclohexane

trans-1,3-dimethylcyclohexane

(+)-2-methylbutane

1-bromo-3-methylcyclohexane

cis-1,3-dimethylcyclohexane is a meso compound
​​​​​​​A meso compound is a compound that contains stereocenters but is achiral. It has a plane of symmetry

6

What is the enantiomer of the (1S,3S)-1-bromo-3-methylcyclohexane?

(1S,3R)-1-bromo-3-methylcyclohexane

(1R,3S)-1-bromo-3-methylcyclohexane

(1R,3R)-1-bromo-3-methylcyclohexane

(1S,3S)-1-bromo-3-methylcyclohexane is not chiral

2 enantiomers have opposite configurations in all chirality centers