What are constitutional isomers?
Compounds with the same molecular formula but different connectivity
Give an example of constitutional isomers of C2H6O.
Ethanol and dimethyl ether
Do constitutional isomers have different properties?
Yes they have completely different physical and chemical properties
What is stereoisomerism?
Isomers with the same connectivity but different 3D arrangement
Why is stereochemistry important in pharmacy?
Many drugs require correct stereochemistry for safety and efficacy
Name the three main types of stereoisomerism.
Conformational optical and geometrical
What are conformational isomers?
Isomers formed by rotation around single bonds
Which conformer of ethane is most stable?
The staggered conformer
Why is staggered ethane lower in energy?
Hydrogens are as far apart as possible reducing repulsion
What is torsional strain?
Energy increase due to eclipsing bonds
What is torsional energy?
Energy needed to rotate from staggered to eclipsed
Which conformation of butane is most stable?
The anti conformation
Which conformation of butane is least stable?
The fully eclipsed conformation
Why is anti-butane most stable?
Methyl groups are maximally separated
Why is cyclopropane strained?
Bond angles are 60� instead of 109�
Why is cyclobutane puckered?
To reduce torsional strain between eclipsed hydrogens
