2 - Stereochemistry and Isomers

What if the lowest-priority group (#4) is in the plane when assigning R/S?

Swap #4 with the group on the dashed wedge, determine R/S using 1 → 2 → 3, then flip the answer because one swap reverses the configuration.

For fischer projections, horizontal lines are ______ and vertical lines are ______

on wedge; on dash

Meso compounds have an….

Internal mirror plane, therefore even though they have chiral centers they are achiral

Constitutional isomer

Same molecular formula, different connectivity (bonding arrangement).

Stereoisomers

Same molecular formula and connectivity, different 3D spatial arrangement.

Enantiomer

Stereoisomers that are non-superimposable mirror images of each other.

Diastereomer

Stereoisomers that are NOT mirror images of each other.

Constitutional isomers vs. stereoisomers

Constitutional isomers differ in connectivity; stereoisomers have the same connectivity but differ in 3D arrangement.