Optical isomerism

When does optical isomerism occur?

What are enantiomers?

• Two compound that form mirror/non superimposable images.

Do optical isomers have similar physical and chemical properties?

• Yes but they rotate polarised light in different directions

• By same degree too

• This is why they are called optical isomers.

Polarimeter

R/S Nomenclature

Racemic mixtures/ racemate

• Contain 50/50 mixture of the two enantiomers so it’s not optically active/ won’t rotate plane-polarised light.

Formation of a racemate

NUC SUB forming racemate

R and S Thalidomide

How is R and S assigned?

• Give priority using C I P

• If it increases clockwise its R

• If not it’s S