Download presentation
Presentation is loading. Please wait.
Published byLorin Haynes Modified over 8 years ago
4
Enantiomers rotate plane polarized light the same magnitude, but opposite directions. clockwise rotation – dextrarotatory (d or +) counterclockwise rotation – levorotatory (l or -) racemic mixture – racemate 50:50 mixture of enantiomers (d,l or ±) No relationship between d,l and R,S.
6
Designating the Configuration of Enantiomers Step 1:Assign priorities 1 (highest) to 4 (lowest) to the four groups attached to the chirality center using the Cahn-Ingold-Prelog sequence rules. Step 2:View the molecule so the bond from the chirality center to group 4 is pointed away from you. 1 to 2 to 3 to 1 clockwise R (rectus) 1 to 2 to 3 to 1 counterclockwise S (sinister)
7
1 to 2 to 3 to 1 is counterclockwise, so S 1 to 2 to 3 to 1 is clockwise, so R
8
1 to 2 to 3 to 1 is counterclockwise, so S 1 to 2 to 3 to 1 is clockwise, so R
9
absolute configuration: the actual 3-D arrangement of groups around a chirality center relative configuration: the configuration of one compound relative to another
10
absolute configuration: the actual 3-D arrangement of groups around a chirality center relative configuration: the configuration of one compound relative to another
11
Properties of Enantiomers Enantiomeric molecules are only different in a chiral environment. They have identical mp, bp, heat of combustion, solubility in H 2 O They have different solubility in one enantiomer of a chiral solvent rate of reaction with one enantiomer of a chiral reagent
12
Resolution: Separating Enantiomers make environment chiral so enantiomers have different properties 1. react with one enantiomer of a chiral compound separate diastereomers and regenerate 2.react with a chiral reagent (enzyme) 3.chromatography with a chiral stationary phase
13
enantiomers to be separated one enantiomer of a chiral amine diastereomeric salts one diastereomer one pure enantiomer
14
Reactions that Produce Enantiomers R S 50% Reactants (achiral or racemic) Products (racemic) (optically inactive)
15
Other Chiral Compounds tetrahedral atoms other than C
16
pyramidal atoms These compounds have been resolved.
17
substituted allenes
18
biphenyls has been resolved half-life for racemization is 78 min at 118 o C
19
helical molecules
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.