CHEM 233 Stereochemistry

What are stereoisomers

same molecular formula, same connectivity, but different arrangements in space

What are constitutional isomers

same molecular formula, different connectivity

two types of stereoisomers,

configurational and conformational

two types of configurational isomers

diastereomers and enantiomers

Conformational isomer —> conformer, what is that?

an isomer of a molecule that differs from another isomer by the rotation of a single bond in the molecule

syn — eclipsed — highest in energy

gauche — staggered (second lowest in energy)

anti — staggered (lowest in energy)

Eclipsed — second highest in energy

What are enantiomers

non-superimposable mirror images

identical physical and chemical properties

(except: interactions with plane polarized light)

What are diastereomers

not mirror images of each other

• similar physical / chemical properties

• E/Z stereoisomers

• compounds with multiple assymetric centres

All assymetric centres are sterecentres, but…

not all stereocentres are assymetric centres

Meso Compound

• more than 1 assymetric centre

• internal plane of symmetry

What is a stereocentre

an atom (usually carbon) with at least three different groups attached, such that swapping any two of these groups creates a different stereoisomer