17.1 chirality Flashcards
What type of isomerism are optical isomers?
Stereoisomerism
What is a chiral molecule?
One that is not superimposed by its mirror image eg hands
What’s a chiral carbon?
A carbon atom bonded to four different groups. It is said to be asymmetric.
Racemic mixture
A mix of equal amounts of enantiomers.
How to test for a racemic mixture? And why does this test show a racemic mix?
Pass plane polarised light through the mixture and if the light doesn’t rotate then it is a racemic mixture. This is because each enantiomer rotates plane polarised light in one direction. If there are equal amounts then the isomers have equal and opposite effects and so rotation is cancelled out.
How many steps in an Sn2 mechanism?
1 step
What does Sn stand for?
Substitution nucleophilic
What does the number after Sn refer to?
The number of species in the rds
What happens in an Sn2 mechanism?
The nucleophile forces a species from the organic compound to replace it and so two species are involved in the transition state.
What shape does the organic compound take before being attacked by the nucleophile but already having had another species detach?
Trigonal planar
Where can the nucleophile attack in the Sn1 mechanism?
Above or below
Why can an Sn1 mechanism form enantiomers?
As the carbocation with a positive charge is open to attack from above or below by equal probability. This can form enantiomers if there are three other different groups attached to the carbon with a positive charge.
What does an Sn1 mechanism form, given that enantiomers are being produced?
A racemic mixture of
