Enantioselective Chromatography Flashcards
Isomers
Isomers are different compounds with the same chemical formula.
Constitutional isomers: compounds that have the same atoms but bonded together in different arrangements.
Stereoisomers
Compounds that have the same molecular formulae and same connectivity between the atoms. by different spatial orientation
Enantiomers
mirror images but not superimposable.
1:1 mixture of enantiomers is called a racemic mixture
Chiral Switching
drugs are now produced in single enantiomeric form (chiral switching) this reduces drug toxic effects.
Chiral seperation
O-phthaldialdehyde (OPA), in combination with an organic thiol, is used to react with amino acid enantiomers and form highly fluorescent diastereomeric compounds that can be separated by chromatography.
Chiral selectors
Macromolecular selectors
Chiral selectors based on nucleotides
Protein chiral selectors
Macrocyclic selectors.
Macrocyclic glycopeptide
Antibiotics
Cyclodextrins
Vancomycin
DNA chiral selectors
Have limited range of analyte selectivity and practical applications
The chiral recognition by oligonucleotides and nucleic acids is due to enantioselective intercalation and or groove binding
Protein chiral selectors
Compatible with a wide number of mobile phases.
Used in HPLC
Cyclodextrin
Ogliosaccharides comprising 40 chiral centres; ability to adapt their shape to that of the analyte; Used for a wide variety of analytes
Chiral stationary phases
Enantiomers can be separated by using chiral stationary phase.
One enantiomer passes through the separation medium quickly while the other enantiomer is held for a longer time due to its strong interaction with the chiral stationary phase.
These interactions include:Hydrogen bonds
Dipole/dipole interactions
Hydrophobic interactions (carbon content)
Steric interactions
Inclusion
Vancomycin
contains 18 stereocentres; used to resolve a wide range of chiral compounds
