3 - Optical Isomerism Flashcards
What happens in Stereoisomerism?
In stereoisomerism the atoms are joined in the same order but have a different arrangement in space.
What molecules do optical isomerism occur in?
Optical isomerism occurs in molecules that contain a chiral carbon atom attached to 4 different atoms or groups. This carbon atom is known as a chiral carbon atom.
How many optical isomers are there per chiral centre?
Two mirror-images are possible in space - they’re not superimposable.
Where is the chiral carbon in amino acids?
In amino acids (except Glycine) the chiral carbon is attached to a carbonyl group, an amine group, a H atom, and an R-group.
How should optical isomers be drawn?
Optical isomers should be draw as mirror images. The geometry around the chiral carbon should be shown as a tetrahedral shape.
How do optical isomers rotate light differently?
One optical isomer rotates light clockwise, and the other optical isomer rotates light anti-clockwise.
What is a racemic mixture? What effect does it have?
A racemic mixture contains equal amounts of both mirror-image isomers. A racemic mixture has no effect on polarised light as the rotations cancel each other out.
Why is optical activity important in amino acids?
Optical activity is important in biological systems where frequently only one of the optical isomers is biologically active.
What’s synthesised naturally in nature? Why?
In nature only one optical isomer is synthesised naturally. This is because only one will interact with an enzyme dude to the stereospecific nature of enzymes.
