What are the total number of stereoisomers of 2,3-dichlorobutane?

1 Answer
Dec 15, 2015

There are three stereoisomers of 2,3-dichlorobutane.


The structure of 2,3-dichlorobutane is #"CH"_3stackrelcolor(blue)("*")("C")"HCl"stackrelcolor (blue)("*")("C")"HClCH"_3#

The two carbon atoms marked with blue asterisks are chiral centres.

The maximum number of stereoisomers is #2^n#, where #n# is the number of chiral centres.

Since #n = 2#, the maximum number of stereoisomers is #2^2 = 4#.

We can write the four possible Fischer structures as


Structures 1 and 2 are two different nonsuperimposable mirror images of each other.

But Structures 3 and 4 are meso compounds.

They are superimposable on each other, so they are the same compound.

So, there are only three stereoisomers of 2,3-dichlorobutane.