Question

How do enantiomers differ physically?

Answer 1

The short answer is "NOT AT ALL".

Explanation:

Enantiomers are non-superposable mirror images. They have identical physical properties, and identical chemistry in ALL ACHIRAL SITUATIONS.

Enantiomers (when the 1 isomer is present in abundance), will differ in their rotation of plane-polarized light. One stereoisomer will rotate plane-polarized light in 1 direction, and its enantiomer will rotate plane-polarized light in the opposite direction (note that this distinction falls outside the prior situation, because we have introduced handedness, chirality, with plane polarized light).

When we introduce another homochiral chemical into the equation, the interaction with a pair of enantiomers is diastereomeric rather than enantiotopic; for instance we add chiral molecule `R'` to react with a mixture of stereoisomers `R` and `S`. This interaction is now diastereomeric: `R'R` and `R'S` ARE NOT MIRROR IMAGES, but diastereomers, which are in principle separable by physical means. Sometimes a homochiral reagent is introduced, such that it reacts preferentially with a particular stereoisomer, and a chemical means to separate the starting enantiomers, a chiral resolution, is feasible.