Deriving Possible Isomers
There is no simple way to know how many
isomers exist for a given molecular
formula, and therefore, it is important to have a systematic method to
Important preliminary steps in the process are:
the IHD to see what types of structures you
- list the functional groups that are possible based
on the molecular formula and IHD.
Once you have done that, here are a
suggestions to aid the drawing process.....
- start with the longest
continuous chain (or ring) first
- move substituents
systematically along the chain, remember to consider all possible relative positions if you have more than one substituent.
- if you have C=C then consider
E- and Z- possibilities or cis- and trans-
for ring systems
- decrease the the chain
length one step at a time and introduce new
- with alkyl substituents, remember that two methyl groups are equivalent to an ethyl and an H-
- watch out that you don't
- if chiral centers are
present then need to consider R and S
do this by identifying the chiral centers.
||© Dr. Ian Hunt, Department of Chemistry, University