Practice Stereoisomer Relationships Study guide
Stereoisomers that are non-superimposable mirror images are enantiomers; stereoisomers that are not mirror images are diastereomers; and if rotation superimposes the two drawings, they are the same compound. The study guide has the decision tree.
Classify each pair below as enantiomers, diastereomers, or identical.
Molecule A
Molecule B
Common Questions
What is the difference between enantiomers and diastereomers?
Enantiomers are a pair of stereoisomers that are mirror images of each other. Some people state that if molecule A and molecule B are enantiomers, then the mirror image of A is superimposable on B. Diastereomers are stereoisomers that are not mirror images. For a pair of diastereomers C and D, the molecules C and D are not superimposable on each other, AND their mirror images are not superimposable.
How do you tell if two molecules are identical?
Two molecules are identical if you can superimpose them by rotation and translation. If every stereocenter has the same R/S configuration in both structures, they are the same compound.
What are structural isomers vs. stereoisomers?
Structural (constitutional) isomers have the same molecular formula but different atom connectivity. Stereoisomers have the same connectivity but differ in the 3D arrangement of atoms.
Do enantiomers have the same physical properties?
Enantiomers have identical physical properties (melting point, boiling point, solubility) except for the direction they rotate plane-polarized light and how they interact with other chiral molecules.