Isomers Flashcards
Three classes
Constitutional, conformational, stereoisomers
Constitutional isomers
Structural isomers that differ in the positions of their constituent atoms
Conformational isomers
Isomers that arise from different orientations around a sigma bond, which may rotate relative to one another
Conformational isomers
Either eclipsed or staggered
Eclipsed > staggered, in terms of energy
Conformational isomers
The relative populations of conformational isomers are temperature dependent
Cyclo- conformational isomers
Stability
Chair>twist>boat
Stereoisomers
Differ in their spatial, 3-D arrangements
Geometrical isomers
When rotation about a bond or bonds is not possible due to a ring system of pi bond
Enantiomers
Nonsuperimposable, chiral mirror images
Diastereomers
Stereoisomers that are not Mirror images of each other
Geometrical isomers are diastereomers
Enantiomers
Have identical physical and chemical properties; they are not easy to separate
Diastereomers
Have different physical and chemical properties; they are easy to separate by conventional means
Racemic mixture
50-50 mixture of a pair of enantiomers
R and S convention
R equals right, S equals left
R and S convention naming steps
- ) assign priorities based on mass
- ) visualize with lowest priority pointing away from you
- ) rotate going 1,2,3
Meso molecules
Have chiral centers but are not chiral overall
Mirror image is identical in every way, have internal mirror plane
Optical activity meso
Optically inactive
Optical activity racemic
Optically inactive
Optical activity enantiomers
Optically active but flip in opposite direction
Optical rotation
Plane polarized light is a group of photons that are all moving in the same direction AND have electromagnetic fields oscillating in the same place
Optical activity chiral centers
Optically active and rotate plane polarized light
