optical isomers

Question 1

what is a chiral molecule?

Answer 1

has 4 different groups attached to a central atom

Question 2

what is optical isomerism

Answer 2

type of stereoisomerism where molecules have the same molecule formula but different arrangments in space

Question 3

what does the presence of a chiral centre lead to

Answer 3

two possible isomers that are mirror images of each other

Question 4

what are two different isomers called

Answer 4

enantiomers

Question 5

features of enantiomers

Answer 5

• they are unique due to their effect on plane-polarised light
• each enantiomer causes the rotation of plane polarised light by 90 degrees in opposite directions

Question 6

how is a racemate formed

Answer 6

when optical isomers are produced as a pair of enantiomers in a 1:1 ratio

Question 7

what is a racemic mixture and how is it formed?

Answer 7

optical rotational effect on polarised light caused by each enantiomer causes the overall effect to be 0 as the opposite directions of rotation cancel out. the mixture is optically inactive (aka racemic mixture)

Question 8

what reaction leads to the formation of a racemic mixture

Answer 8

nucleophillic addition reaction

Question 9

nucleophilic addition

Answer 9

nucleophiles attack molecules with a carbonyl group from above or below the carbon-oxygen double bond. so two possible products of the reaction are mirror images (optical isomers)

Question 10

what is an isomer

Answer 10

same Mr, different arrangement of atoms

Question 11

what are stereoisomers

Answer 11

same structural formula, arranged differently in space

Question 12

nucleophillic addition forming optical isomers

Answer 12

Nucleophiles attack a molecule with a carbonyl group above/below C=O