This slide gives the best explanation and knowledge about isomerism.

1. Created by Usman Yousaf
Aug 8, 2016

2.  Molecules which have the same
molecular formula, but differ in the
arrangement of their atoms, are called
isomers.
 Constitutional (or structural) isomers differ
in their bonding sequence.
 Stereoisomers differ only in the
arrangement of the atoms in space. =>

3. IsomersIsomers
StereoisomersStereoisomers
connectivity =connectivity =
orientationorientation≠≠
ConstitutionalConstitutional
structuralstructural
connectivityconnectivity ≠≠
DiastereomersDiastereomers
not mirror images
EnantiomersEnantiomers
Non-superimposable mirror image

4. CH3 O CH3 and CH3 CH2 OH
CH3
CH3
and
=>

5. ethaneethane
CC22HH66 oror
CHCH33CHCH33
alkanes: propane (CHalkanes: propane (CH33CHCH22CHCH33))
H C
H
H
C H
H
H
C H
H
H

6. propane (Cpropane (C33HH88))
H C
H
H
C
H
H
C H
H
H
alkanes: CHalkanes: CH33CHCH22CHCH33

7. propane (Cpropane (C33HH88))
H C
H
H
C
H
H
C H
H
H
alkanes: CHalkanes: CH33CHCH22CHCH33

8. propane (Cpropane (C33HH88))
H C
H
H
C
H
H
C H
H
H
C H
H
H
C H
H
H
oror
alkanes: propanealkanes: propane

9. butane (Cbutane (C44HH1010))H C
H
H
C
H
H
C H
H
H
propanepropane
(C(C33HH88))
H C
H
H
C
H
H
C C
H
H
H
H
H
H C
H
H
C
C
H
C H
H
H
H H
H
alkane isomers:alkane isomers: How many CHow many C55HH1010
isomers?isomers?

10. butane (Cbutane (C44HH1010))
H C
H
H
C
H
H
C C
H
H
H
H
H
H C
H
H
C
C
H
C H
H
H
H H
H
alkane isomers:alkane isomers: How many CHow many C55HH1010
isomers?isomers?

11. butane (Cbutane (C44HH1010))
H C
H
H
C
H
H
C C
H
H
H
H
H
H C
H
H
C
C
H
C H
H
H
H H
H
alkane isomers:alkane isomers: How many CHow many C55HH1212
isomers?isomers?
C C C C C
H
H
H
H
H
H
H
H
H
H
H
H

12. How many CHow many C55HH1212 isomers?isomers?
these two structuresthese two structures
are identicalare identical
bond linebond line
structures:structures:

13. alkane isomers:alkane isomers: How many CHow many C55HH1212 isomers?isomers?
these two structuresthese two structures
are identicalare identical

14. alkane isomers:alkane isomers: How many CHow many C55HH1212 isomers?isomers?
these two structuresthese two structures
are identicalare identical

15. alkane isomers:alkane isomers: How many CHow many C55HH1212 isomers?isomers?

16. Butane = CButane = C44HH1010, CH, CH33CHCH22CHCH22CHCH33
H
H
H H
H HH H
HH
C C
H
H
H
H
H
C
H
H
C
H
H
H

17. Butane, bond rotationsButane, bond rotations

18. rotations about singlerotations about single
bonds are very fast.bonds are very fast.
Butane, bond rotationsButane, bond rotations

19. = butane= butane
Butane, bond rotationsButane, bond rotations

20. ==
Butane, bond rotationsButane, bond rotations

21. Isomers of CIsomers of C44HH1010..
==
==

22. Draw all of the isomers with
the formula C4H9Cl.
Cl
Cl
Cl
Cl
Stereoisomers

23. Draw all of the isomers with
the formula C4H9Cl.
ClH HCl
Are these two
structures identical?

24. Draw all of the isomers with
the formula C4H9Cl.
HCl
A 1:1 mixture of
enantiomers is called
a racemic mixture.
ClH
+ H Cl +

25. H
Cl
H
Cl Are these two
structures identical?
mirror

31. Cis - same side Trans - across
Cis-trans isomers are also called geometric isomers.
There must be two different groups on the sp2
carbon.
No cis-trans isomers possible