4.1 Stereoisomerism

How can a molecule be classified as an optical isomer?

It must have a chiral centre.

What is a chiral centre?

A carbon bonded to 4 different groups e.g. amino acids.

What are the mirror images of chiral molecules?

Enantiomers

What do enantiomers do?

Rotate the plane polarised light in opposite directions.

Two types of enantiomers.

R (to the right/clockwise) and S (to the left/anticlockwise). Can be called D or L too.

What is a mixture of enantiomers called?

Racemate or racemic mixture.

What shape can enantiomers always be drawn as?

Tetrahedral

How can chiral molecules always be described?

Optically active

Racemeters have no overall effect on what?

In rotation of plane of polarised light

Example of S and R isomers being different.

S thalidomide is an effective drug.

R thalidomide is a dangerous drug.

Which is an E and Z isomer?

E isomer is functional groups on opposite sides and Z is the same sides.