Optical Isomerism Flashcards
What kind of molecules show optical isomerism?
Chiral molecules (4 different groups attached)
What is a racemic mixture or racemate?
When a substance has a 50/50 mix of two enantiomers
What is an enantiomer?
An optical isomer
Optical isomerism is a form of what type of isomerism?
A form of stereoisomerism
How do enantiomers differ?
In their effect on plane polarised light and their reaction with other chiral molecules
What does a polarimeter do?
Measure how the plane of light is rotated when polarised light is passed through a sample
How does the electrophilic addition of HBr to but-2-ene form enantiomers?
The intermediate formed is a trigonal planar.
Br is equally likely to attack from above as below, thus forming the enantiomers (and therefore a racemate)
Why is optical isomerism important to consider in medicine and drugs?
Most of the reactions that occur in the body are very shape specific. Therefore, often only one enantiomer will have an effect.
Many drugs are optically active, with only one enantiomer having an effect. However, many drugs are racemates. Why?
Only one has an effect, so (in most cases) other is not harmful
Cheaper to not separate
