1. Constitutional Stereoisomers
Isomerism
Constitutional
Stereoisomers

2. Isomers Different compounds that have the same molecular formula.
C5H12

3. Structural Formulas for C4H10O Isomers
Kekulé Formula
Condensed Formula
Shorthand Formula

4. Constitutional Isomers
Constitutional isomers can be:
Skeletal
Functional
Positional
Also referred to as structural isomers, are compounds that differ from each other in connectivity.
Connectivity is the order of the attachment of atoms to each other.

5. Constitutional isomers can be:
Skeletal
Functional
Positional
C6H14

6. Constitutional isomers can be:
Skeletal
Functional
Positional
C5H12O

7. Constitutional isomers can be:
Skeletal
Functional
Positional
C5H12O

8. Constitutional isomers can be:
Skeletal
Functional
Positional
C4H8

9. Constitutional isomers can be:
Skeletal
Functional
Positional
C5H12O

10. Constitutional isomers can be:
Skeletal
Functional
Positional
C5H12O

11. Constitutional isomers can be:
Skeletal
Functional
Positional
C4H8

12. Stereoisomers
are compounds whose atoms are connected in the same way but with different geometry or configuration.
Configuration is the arrangement of atoms or group of atoms in space at the stereocenter.
Stereocenter is a carbon atom bearing other atoms or groups of atoms whose identities are such that an interchange of the two groups produces a stereoisomer.

13. Stereoisomers can be: Geometric Isomer Optical Isomer Cis Enantiomers
Trans
Diastereomers E R Z S

14. Conformations
The different arrangement of atoms that result from rotation around a single bond.
A specific conformation is called a conformer (Conformational isomer)
Eclipsed / Staggered (for alkane)
Chair (for cyclohexane)
Unlike constitutional isomers, different conformers usually interconvert too rapidly for them to be isolated

15. Conformations
Chemists represents conformers in two ways:
Sawhorse representation
Newman projection

16. The Cis and Trans configuration of 2-Butene:
Trans-2-Butene
Cis-2-Butene

17. The Cis and Trans configuration of 1,4-Dimethycyclohexane
Cis- 1,4-Dimethylcyclohexane
Trans- 1,4-Dimethylcyclohexane

18. The E and Z configuration of 3-methyl-2-pentene:
Z-3-methyl-2-pentene
E-3-methyl-2-pentene

19. Enantiomers
Isomers that are mirror images of each other but are non-superimposable
Enantiomers have identical physical properties, except for the direction of rotation of the plane of a polarized light.
Enantiomers have identical chemical properties except toward optically active reagents.

20. Enantiomers

21. Diastereomers have different physical properties.
Isomers that are non-mirror images of each other and are non-superimposable.
Diastereomers have similar chemical properties, since they are members of the same family.
Diastereomers have different physical properties.

22. Diastereomers

23. The R and S configuration of Bromochloroiodomethane:
R (Latin: rectus, right)
S (Latin: sinister, left)

24. Chiral Carbon
A carbon where four different atoms or group of atoms are attached to.

25. Constitutional isomer
Practice Exercise: 1)
Tell whether the given pair of compound are constitutional isomers, stereoisomers, same compound or not an isomer.
Constitutional isomer
(positional)

26. Constitutional isomer
Practice Exercise: 2)
Tell whether the given pair of compound are constitutional isomers, stereoisomers, same compound or not an isomer.
Constitutional isomer
(functional)

27. Constitutional isomer
Practice Exercise: 4)
Tell whether the given pair of compound are constitutional isomers, stereoisomers, same compound or not an isomer.
Constitutional isomer
(skeletal)