Chapter 25- Optical Isomerism Flashcards
What are optical isomers?
Molecules with the same molecular formula but different arrangements of atoms in space
What is required for optical isomers?
An asymmetric carbon atom
What is a chiral centre/ chiral carbon?
A carbon atom bonded to four different groups so there is no line of symmetry in the molecule
What are enantiomers?
Two molecules that are non-superimposable mirror images of each other
How do enantiomers affect plane polarised light?
When plane polarised light is shone through samples of the different enantiomers, they rotate it through the same angle in opposite directions.
What is a racemic mixture/ racemate?
A mixture containing equal amounts of enantiomers
What happens when plane-polarised light is shone through a racemate?
The optical rotational effect of each enantiomer causes an overall effect of no rotation as the opposite directions cancel out. This causes it to be optically inactive.
How are racemic mixtures produced?
When enantiomers are produced in a 1:1 ratio. They are formed in this way due to a nucleophilic addition reaction.
How are enantiomers produced through nucleophilic addition?
Nucleophiles can attack a planar molecule with a carbonyl group from above or below with equal probability. The two possible products are mirror images and produced in 1:1 ratio
What is a carbonyl group?
A functional group with a C=O double bond
