Isomers Flashcards
What is an isomer?
Same molecular formula, different structure
What is a Constitutional Isomer?
Different connectivity, may have different functional groups
What is a Stereoisomer?
Same functional groups and connectivity, yet different
spatial arrangement
What is a Conformational Isomer?
Stereoisomers that can interconvert via bond rotation
What is a Configurational Isomer?
Stereoisomers that cannot interconvert through bond rotation
Must break bonds to make the molecules equivalent
What is a Geometric Isomer?
Configurational isomers with restricted rotation:
Cis / Trans (di-substituted);
E / Z (tri- and tetra-substituted)
What is an Optical Isomer?
Configurational isomers with different 3-D position of groups
Optical isomers will be prevalent drugs
What is an Enantiomer?
Optical isomers that are non-superimposable, mirror images
Enantiomers are pairs (R and S; R,S and S,R)
What is a Diastereomer?
Isomers that are non-superimposable, non-mirror images
More than one chiral center (R,S and R,R); includes epimers
A molecule can have many diastereomers
What is a Meso compound?
A type of optical isomer that has a plane of symmetry
One molecule will appear to be two enantiomers
Symmetry is important in 3D structure
Enantiomers vs Diastereomers
Enatiomers:
• Non-superimposable • Mirror images • Not resolvable
Diasteromers:
• Non-superimposable • Non-mirror images • Resolvable
Examples: Enantiomers / Diastereomers
