### Stereoisomers in Molecules with Two Chiral Centers

The number of possible stereoisomers of a molecule is related to the number of chiral centers present in a molecule.

The exact relationship is m = 2^{n}

where m is the number of possible isomers and n is the number of chiral centers.

Thus, for molecules with **two** chiral centers there are **four** possible stereoismers. (More complicated systems will not be considered here.)

Consider the stereoisomers of 2-bromo-3-fluorobutane:

(2R,3R)