PHAR2821 Lecture Notes - Lecture 1: Racemic Mixture, Stereocenter, Optical Rotation
Document Summary
Structural isomers: (isomers whose atoms have different connectivity: functional group (same molecular formula, different connectivity, tautomeric (same molecular formula, h atom moves, always in equilibrium with each other. Most stable tautomer usually stays or exists more: positional. Stereoisomers: (isomers that have the same connectivity but differ in the arrangement of their atoms in space: enantiomers: stereoisomers that are mirror reflections of each other. Contain a stereogenic (chiral) centre usually a c. 50:50 mixture of enantiomers is called a racemic mixture. A pair of enantiomers have identical physical and chemical properties (e. g. mp, bp, Nmr spectra, except for: their ability to rotate the plane of plane polarised light (optical rotation) and, their chemical reactions with other molecules containing a stereogenic centre (e. g. enzymes, receptors, nucleic acids) <<< key differences. There is no simple relationship between direction of rotation of plane polarised light. Glyceraldehyde is the standard for carbohydrates and dextrorotatory (+)- isomer is designated d. [(-) is this l]
