Isomerism

Question 1

Define Isomers

Answer 1

Molecules with = molecular formula but different atom arrangement

Question 2

Define Structural Isomerism

Answer 2

= molecular formula but different structural atom arrangement.

Question 3

Outline the different types of Structural Isomers

Answer 3

Position Isomers (diff functional group position)
Chain isomers (straight chains or branched)
Functional group isomers (different functional group)

Question 4

Define Stereoisomerism

Answer 4

= molecular formula but different spatial arrangement.

Can be Optical or Geometric

Question 5

Define Geometric Isomers

Answer 5

E = functional groups on different sides
Z= functional groups on same sides (Zame Zides)

Question 6

Define the CIP Priority rules

Answer 6

Cahn-Ingold-Prelog
Determines whether isomer is E or Z
1st atom bonded to C=C with higher Ar has priority

Question 7

Define Optical Isomerism

Answer 7

Stereoisomerism type
Asymmetrical carbon called chiral carbon

Question 8

Define Chiral Centres

Answer 8

4 different groups bonded around it - no symmetry line

Question 9

Define Optical Isomers

Answer 9

2 possible isomers that are mirror images of each other

Question 10

Define enantiomers

Answer 10

2 different isomers that rotate plane polarised light by 90 degrees in opposite directions

Question 11

Define a racemic mixture

Answer 11

Enantiomers are formed in a 1:1 ratio

Question 12

What is the optical rotational effect in racemic mixtures? What is this called?

Answer 12

None equal ratio so opposite rotations cancel = optically inactive

Question 13

Outline how enantiomers are formed

Answer 13

Nucleophilic addition

Question 14

Outline the Nucleophilic addition steps that form enantiomers

Answer 14

Step 1:
Nucleophile attacks Carbonyl group from above or below.
C=O bond breaks forming O-
Step 2:
O- attacks H+ forming R-OH