3.3.1 Introduction to organic chemistry, 3.3.7 Optical isomers

Question 1

What is structural isomerism?
Give some examples

Answer 1

Molecules with the same molecular formula but a different structural formula.
Position, chain, functional group

Question 2

What is stereoisomerism?
Give some examples

Answer 2

Molecules with the same structural formula but a different arrangement of atoms in space.
E-Z, optical isomers, cis-trans

Question 3

What is the rule for geometric ismoers?

Answer 3

E = highest priority (atomic number) are on different sides
Z = highest priority are on same side

Question 4

How do geometric isomers form?

Answer 4

Restricted rotation becuase of the pi bond in the C=C bond

Question 5

What can be used to ensure only one optical isomer is produced?

Answer 5

Enzyme

Question 6

What is a racemic mixture?

Answer 6

• Optically inactive
• 50/50 mixture of enantiomers

Question 7

How does a racemic mixture form?

Answer 7

• The carbonyl group C=O is planar
• There is equal probability that the nucleophile will attack above and below the plane
• Produces an equal mixture of enantiomers

Question 8

How can you distinguish between 2 enantiomers?

Answer 8

• Shine plane polarised light through mixtures
• Enantiomers will rotate the light in opposite directions