Resolution of Enantiomers Separation of a racemic mixture

$Diastereomers • Diastereomers have different physical properties: v. BP, MP, density, refractive index, solubility$

Resolution of Enantiomers • In 1847, Pasteur performed the first resolution of enantiomers from

Resolution of Enantiomers • A common method uses a chiral resolving agent. • An

Resolution of Enantiomers • Conversely, an optically pure base reacts with a racemic mixture,

Ibuprofen enantiomers Ibu(+) Ph(-) Ibu(+) Ibu(-) 2 Ph(-) Ibu(+) Ibu(-)Ph(-) Ibu(+)Ph(-) Ibu(-)Ph(-) Ibu(+) Ibu(-)

Slides: 6

Download presentation

Resolution of Enantiomers Separation of a racemic mixture into its two respective enantiomers

$Diastereomers • Diastereomers have different physical properties: v. BP, MP, density, refractive index, solubility$

Diastereomers • Diastereomers have different physical properties: v. BP, MP, density, refractive index, solubility v. Can be separated through conventional means (distillation, recrystallization, chromatography) mp = 158 o. C mp = 256 o. C

Resolution of Enantiomers • In 1847, Pasteur performed the first resolution of enantiomers from a racemic mixture of tartaric acid salts. • The different enantiomers formed different shaped crystals that were separated by hand using tweezers.

Resolution of Enantiomers • A common method uses a chiral resolving agent. • An optically pure acid forms diastereomeric salts when reacted with a racemic amine, (+/-) bases.

Resolution of Enantiomers • Conversely, an optically pure base reacts with a racemic mixture, (+/-) isomers of acids, to produce diastereomeric salts. • S-(-)-α-phenethylamine can resolve a racemic mixture of ibuprofen, [Ibu(-)] [Ibu(+)] (R, S)-2 -(4 -(2 methylpropyl)phenyl)propanoic acid • S-(-)-α-phenethylamine [Phe(-)] reacts with a racemic mixture of ibuprofen, [Ibu(-)] [Ibu(+)] (R/S) to produce [Phe(-)] [Ibu(-)] (S, S) and [Phe(-)] [Ibu(+)] (S, R), which can be separated.

Ibuprofen enantiomers Ibu(+) Ph(-) Ibu(+) Ibu(-) 2 Ph(-) Ibu(+) Ibu(-)Ph(-) Ibu(+)Ph(-) Ibu(-)Ph(-) Ibu(+) Ibu(-) Diastereomers (different solubilities) Ph(-) Ibu(-)