Advices For Studying Organic Chemistry

(R)-1-Bromo-2-butanol (S)-2-butanol

1. The (R-S) designation changes while the reaction proceeds with retention of
   configuration.


2. The product of the reaction has the same relative configuration as the reactant.

5.14A RELATIVE AND ABSOLUTE CONFIGURATIONS

1. Before 1951 only relative configuration of chiral molecules were known.
   
   
   1. No one prior to that time had been able to demonstrate with certainty what actual
      spatial arrangement of groups was in any chiral molecule.
   
   
   
   


2. CHEMICAL CORRELATION: configuration of chiral molecules were related to each
   other through reactions of known stereochemistry.


3. Glyceraldehyde: the standard compound for chemical correlation of
   configuration.

H C

C

O H

C

O H

OH

CH 2 OH

HO C H

CH 2 OH

and

(R)-Glyceraldehyde (S)-Glyceraldehyde
D-Glyceraldehyde L-Glyceraldehyde

1) One glyceraldehydes is dextrorotatory (+) and the other is levorotatory (–).

2) Before 1951 no one could be sure which configuration belonged to which

enantiomer.

3) Emil Fischer arbitrarily assigned the (R) configuration to the (+)-enantiomer.

4) The configurations of other componds were related to glyceraldehydes through

reactions of known stereochemistry.

4. The configuration of (–)-lactic acid can be related to (+)-glyceraldehyde through
   the following sequence of reactions: