What is the difference between a stereogenic center and a chiral center?
1 Answer
Chiral centres are a subset of a stereogenic centres.
Explanation:
Many texts say they are the same, but there is a subtle difference.
A chiral centre is an atom that has four different groups attached.
Thus, in ribitol, carbons 2 and 4 are chiral centres.
A stereogenic centre is any atom for which exchanging two groups creates a different stereoisomer.
Thus, all chiral centres are stereocentres.
However, not all stereocentres are chiral centres.
Note that ribitol is a meso compound.
Carbon 3 is a stereogenic centre, because the two attached carbon chains are mirror images of each other and hence not identical.
If we interchange the
Xylitol is a stereoisomer, and it is also a meso compound.
Interchanging
Thus, carbon 3 is a stereogenic center, but not a chiral centre.