Chapter 4-1

Optical purity is usually reported in percent

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Unformatted text preview: tiomeric excess is the % of the sample that is non-racemic. For example, 80% ee means that there is 90% of one enantiomer and 10% of the other. Vocabulary •(R) or (S): identifies the configuration of a stereocenter using the CIP priority system •d- or (+): indicates that a (chiral) compound rotates light in a clockwise direction (this has no correlation with S or R) •l or (-): indicates that a (chiral) compound rotates light in a counterclockwise direction (this has no correlation with S or R) •dl or (+/-) or rac-: indicates a racemate Resolution of Enantiomers mixture of 2 diastereomers (R)-compound X (S)-compound X react or somehow associate with: (R)-compound Y (R)-compound X (S)-compound X (R)-compound Y (R)-compound Y racemic mixture of enantiomers Single enantiomer Separate by some technique (chromatography, crystallization, distillation, etc.) (S)-compound X single diastereomer (R)-compound Y (R)-compound X (R)-compound Y single diastereomer somehow remove compound Y (S)-compound X single enantiomer (R)-compound X single enantiomer Reaction Using Diastereomers to Separate Enantiomers τηισνιτρ γ εν λ νε ο ο παιρ ισβασ χ ι Me thi s hydrogen i s aci di c H 2N Με Χλ τηισνιτρ γ εν λ νε ο ο πα ρ ισ βασ χ ι ι τηισ ηψδρ γ εν ο ισ α ιδιχ χ O (R)-2-chl oropropri oni c aci d Me OH Cl σ παρ τε εα Τηε Ρ ,Σ− ιασ ερ οµ ερ οφ τηε σ λ δ τε ατ Με (R)-α− ετηψλ ενζψλ µ ινε µ β α Ο Ο Η3 Ν Με Resolution of Enantiomers O (S)-2-chl oropropri oni c aci d Me OH Cl (Ρ )− − ετηψλ ενζψλ µ ινε αµ β α Ο Με Χλ Ο Η3 Ν Με Η2 Ν Τηε Ρ ,Ρ − ιασ ερ οµ ερ οφ τηε σ λ δ τε ατ Ο Με Χλ αχιδιφψ ΟΗ Με Χλ Ο Ο Η3 Ν Με Με Χλ Ο Με ΟΗ Ο Ο Η3 Ν Με (Ρ )− − ηλ ρ πρ πρ ονιχ αχιδ 2χ οο ο ι αχιδιφψ Χλ (Σ)− − ηλ ρ πρ πρ ονιχ αχιδ 2χ οο ο ι Chiralityounds Without Stereocenters Without Stereogenic Centers Chiral Comp Ther e i s hi nder ed r otati on ar ound thi s bond! H H Me Me Me Me H H NO2 O2N NO2 mi r r or pl ane O 2N mi r r or pl ane mi r r or pl ane Chirality Without Stereocenters Me C H H Me Why is 1,3-dimethylallane (1,3-dimethyl-2,3-pentadiene) chiral?...
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