Stereoisomerism occurs when organic compounds have the same molecular formula and the same structural formula, but the atoms in the molecules have different spatial arrangements.
So, how do we calculate and determine the maximum number of stereoisomers a molecule can have?
Provided there is no internal plane of symmetry in the structure of a molecule, and chirality occurs only due to chiral centres,
the maximum number of stereoisomers a molecule can have = 2m+n
m = number of chiral centres; and
n = number of double bonds that can give rise to cis-trans isomers
Let’s take methoprene molecule as an example.
There is only one chiral centre in a methoprene molecule.
Both the C=C double bonds also satisfy the criteria for cis-trans (geometric) isomerism.
As such, the maximum possible number of stereoisomers for methoprene is 2m+ n = 2(1+2) = 23 = 8.
I hope the above discussion is clear for you.
How about working on a slightly easier question on your own? You can leave your answer in the Comment Section below:
What is the maximum number of stereoisomers for an organic compound with the structural formula CH3CH=CHCH(CH3)CH2CH3?
Clue: Draw out the full structural formula first.
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