2.3. Stereochemistry Flashcards
What are the three types of isomerism?
Structural Isomerism
Geometric Isomerism
Optical Isomerism
Why do compounds such as alkenes have geometric isomers?
Due to the fixed double bond. One end of the alkene can’t rotate around the double bond.
What are the two types of geometric isomer?
Cis-isomers and trans-isomers.
Which geometric isomers have higher melting points?
Transisomers.
Where else can geometric isomerism occur?
In compounds with saturated C-C rings.
What is another word for optical isomers?
Enantiomers.
What do these two isomers look like compared to each other?
They are mirror images of each other.
What is the only property that is different between the two enantiomers?
Their effect on plane-polarised light.
If plane-polarised light is passed through a solution with one optical isomer in it the plane will be rotated by a certain angle. When passed through a solution with the other optical isomer the plane is rotated by the same angle, but in the other direction (this only happens if they’re both the same concentration).
What happens if plane-polarised light is passed through a solution with an equal amount of both enantiomers?
Nothing.
What does racemic mean?
The solution has equal amounts of both enantiomers.
