3.3.7 - Optical isomers

Question 1

Optical isomers definition

Answer 1

Molecules with the same molecular and structural formula, but are mirror images of each other.

Question 2

What is a chiral carbon?

Answer 2

Carbon atom with four different groups attached

Question 3

Effect of plane-polarized light on optical isomers

Answer 3

Optical isomers will rotate in opposite directions to this light

Question 4

What is a racemic mixture (racemate)?

Answer 4

• Equal mix of 2 enantiomers ( R & S )
• Optically inactive (rotation cancels out)

Question 5

Why would a product have no effect on plane polarised light? (3)

Answer 5

1. C=O bond is planar, equal chance of H+ nucleophile attacking from the top or bottom
2. 50/50 split of each enantiomer (racemic mixture)
3. Enantiomers rotate plane polarised light in opposite directions, racemic mixture = cancelling out