Ch. 13.2: Stereoisomerism

Question 1

What are stereoisomers?

Answer 1

They have the same structural formula but a different arrangement of the atoms in space.

Question 2

What are the two types of stereoisomerism ?

Answer 2

E/Z isomerism

Optical Isomerism

Question 3

What is the difference between the two types of isomerism?

Answer 3

E/Z isomerism can only occur in compounds with a C=C double bond

Optical isomerism can occur in a much wider range of compounds

Question 4

Why is there stereoisomerism around double bonds ?

Answer 4

Rotation about the double bond is restricted and the groups attached to each carbon atom are therefore fixed relative to each other.

Question 5

What are the conditions for E/Z isomerism ?

Answer 5

• a C=C double bond

- different groups attached to each carbon atom of the double bond

Question 6

How do you remember if something is Z ( cis ) or E ( trans )

Answer 6

Zame Zide = Z

Evanding = E

Question 7

What isomerism is it when there are 2 H atoms each attached to a double bonded carbon are they are on the same side ?

Answer 7

Cis

Question 8

What isomerism is it when there are 2 H atoms each attached to a double bonded carbon are they are on opposite sides?

Answer 8

trans

Question 9

How does isomerism work when they are no H atoms or only 1 H atom?

Answer 9

If the elements / groups with the higher atomic numbers are on the same side then Z

If they are diagonally opposite each other then they are E

Question 10

What are the Cahn - Ingold - Prelog rules?

Answer 10

If the elements / groups with the higher atomic numbers are on the same side then Z

If they are diagonally opposite each other then they are E