Polymers of Life 4: Optical Isomers Flashcards
Definition of chiral carbon
- Carbon attached to 4 different groups
- represented with star next to carbon
Definition of optical isomers
- 2 forms exist which are non-superimposable mirror images of each other
Definition of non-superimposable
You can’t stack one form exactly on top of the other
How do you specify that a molecule is a mirror image
Give example
With positive and negative signs
Eg. Negative lactic acid is found and sour milk whereas positive lactic acid is found in muscles
( function of molecule changes as they are different )
Give an example of something that is non- superimposable in real life
- our hands
- you can’t superimpose your hand because your pinky finger and thumb are in the wrong position
What is a molecule with a carbon with four different groups attached called
Chiral or optically active
What is another name for optical isomers
Enantiomers
How do you distinguish optical isomers
By using:
- / -
- D / L
- R / S
What category of a isomerism does optical isomerism fall under
Stereoisomerism ( other type is E/Z isomerism )
How do you enantiomers differ
- behave identically in ordinary reactions
- physical properties tend to be the same
- some behave differently in the presence of other chiral molecules & with their effect on plane polarised light
How do you work out if a molecule is optically active
- draw out the structure
2. Find the chiral carbon
How do you differentiate enantiomers
- their effect on plane polarised light
- reaction with other chiral molecules
Definition of plane polarised light
Vibrates in only One Direction
light waves vibrations are perpendicular to the direction of travel of the wave
What do you optical isomers due to plane polarised light
They have the capacity to rotate the plane of the plane polarised light
Describe how different enantiomers affect plane polarised light
- -ve = anti-clockwise rotation
- +ve = clockwise rotation
- +ve & -ve ( race mate ) = no overall effect
