CHEM 341 Lecture Notes - Enantiomer, Optical Rotation, Substituent
Document Summary
Each optically active compound has its own specific rotation. Two enantiomers have specific rotations with opposite signs. A pair of molecules that are non-superimposable mirror images. Models needed to convince yourself whether they are superimposable. Enantiomers are identical in all respects except the direction they rotate plane polarized light other physical properties are the same (mp, bp, density, &c. ) Naming system indicates substituents in space the r/s system. Note: atomic numbers do not add up, one group with higher atomic number overrules two (or more) with a smaller one. Add a neighboring atom for each extra bond. Prioritize substituents following the rules, from highest (1) to lowest (4) Orient molecule so that lowest priority substituent (4) is pointing away from you. Starting from highest priority substituent (1) move to second highest (2), and then to third highest (3) Taking the mirror image of a stereoisomer switches r and s. Exchanging any two groups on a stereocenter switches r and s.
