Editing Stereocenter (section)

==Possible number of stereoisomers==
Stereoisomers are compounds that are identical in composition and connectivity but have a different spatial arrangement of atoms around the central atom.<ref name=":0">{{Cite book |last1=Brown |first1=William |title=Organic Chemistry |last2=Iverson |first2=Brent |last3=Anslyn |first3=Eric |last4=Foote |first4=Christopher |publisher=Cengage Learning |year=2018 |isbn=978-1-305-58035-0 |edition=8th |location=Boston, MA |pages=117,137–139}}</ref> A molecule having multiple stereocenters will produce many possible stereoisomers. In compounds whose stereoisomerism is due to [[Tetrahedral molecular geometry|tetrahedral]] (sp<sup>3</sup>) stereogenic centers, the total number of hypothetically possible stereoisomers will not exceed 2<sup>''n''</sup>, where ''n'' is the number of tetrahedral stereocenters. However, this is an upper bound because molecules with symmetry frequently have fewer stereoisomers. 

The stereoisomers produced by the presence of multiple stereocenters can be defined as [[Enantiomer|enantiomers]] (non-superposable mirror images) and [[Diastereomer|diastereomers]] (non-superposable, non-identical, non-mirror image molecules).<ref name=":0" /> Enantiomers and diastereomers are produced due to differing [[Cahn–Ingold–Prelog priority rules|stereochemical configurations]] of molecules containing the same composition and connectivity (bonding); the molecules must have multiple (two or more) stereocenters to be classified as enantiomers or diastereomers. Enantiomers and diastereomers will produce individual stereoisomers that contribute to the total number of possible stereoisomers. 

However, the stereoisomers produced may also give a [[meso compound]], which is an achiral compound that is [[Chirality (chemistry)|superposable]] on its mirror image; the presence of a meso compound will reduce the number of possible stereoisomers.<ref name=":3">{{Cite journal |last=Soderberg |first=Timothy |date=2019-07-01 |title=Organic Chemistry with a Biological Emphasis Volume I |url=https://digitalcommons.morris.umn.edu/chem_facpubs/1 |journal=Chemistry Publications |pages=170,177}}</ref> Since a meso compound is superposable on its mirror image, the two "stereoisomers" are actually identical. Resultantly, a meso compound will reduce the number of stereoisomers to below the hypothetical 2<sup>''n''</sup> amount due to symmetry.<ref name=":0" />

Additionally, certain configurations may not exist due to [[Steric effects|steric]] reasons. [[Cyclic compound|Cyclic compounds]] with chiral centers may not exhibit chirality due to the presence of a two-fold rotation axis. [[Planar chirality]] may also provide for chirality without having an actual chiral center present.