Isomerism Flashcards
Stereoisomerism, Chiral Molecule, Optical isomerism and activity, Enantiomers
Stereoisomerism
What is stereoisomerism?
The phenomenon wherein different compunds have the same structural formula but different relative arrangement.
Stereosiomers are isomers with same bond connectivity.
Chirality
What is Chiral Carbon atom?
The carbon atom which is attatched to 4 different atoms/groups
Chirality
Define Chiral Molecule.
Moelcule containing chiral carbon and doesn’t superimpose perfectly on its mirror image
Chirality
State characteristics of Chiral Molecule
Comparison with mirror image
- Doesn’t superimpose perfectly on mirror image.
- Chiral molecule and mirror image have same molecular and structural formula.
- Spatial arrangement of attatched group is diff for moelcule and mirror image.
- Chiral molecule and its mirror image are stereoisomers of each other
Chirality
What is handedness?
Handedness/Chirality is the relationship between the chiral molecule and its mirror image.
Optical Isomerism
What is optical isomerism?
Isomersism in which the isomers have different optical activity.
Optical isomerism
Explain optical isomerism with the help of chlorobutane.
- It has one chiral carbon atom
- Spatial arrangement of the 4 groups is diff.
- It cannot superimpose perfectly on its mirror image.
Optical Activity
How is ordinary light polarized?
- Ordinary light consists of EM waves having oscillations in all planes perpendicular to direction of propogation.
- When ordinary light is passed through Nicol’s prism, oscillation in only one phase emerges out.
- This is known as plane polarised light.
Optical Activity
How is Nicol’s Prism created?
The Nicol prism consists of two specially cut calcite prisms bonded together with an adhesive known as Canada balsam.
Optical Activity
What happens when plane polarised light is passed through optically active compunds?
- Incident light undergoes rotation of its plane of polarisation.
- The rotation is either clock-wise or anti-clockwise.
Optical Activity
What are optically active compounds? Give examples.
Compounds which rotate the plane of plane polarised light are known as optically active compounds.
e.x. Sugar, Lactic Acid.
Optical activity
What is optical rotation?
- Optical activity is expressed in terns of optical rotation.
- It is the angle through which a substance rotates the plane polarised light passing through it.
- Rotated towards -
a. Right (+) - Dextrorotatory
b. Left (-) - Laveorotatory
Enantiomers
Define enantiomorphs.
The optical isomers which are non superimposable on their mirror image.
ex. 2 chloro butane
Enantiomers
Comment on the physical and chemical properties of entantiomers
Physical -
- Identical properties
- Differ in sign of rotation
Chemical -
- Different properties towards different reagent.
Enantiomers
What is a Racemic mixture?
It is the equimolar solution of enantiomers.
