YOU CANNOT CREATE A CHIRAL RESULT

1
YOU CANNOT CREATE A CHIRAL RESULT BY REACTION
OF TWO ACHIRAL SUBSTANCES
Examples using the stereospecific cis-hydrogenatio
n reaction .. that is
a syn addition
2
INTERACTION OF ACHIRAL OBJECTS GIVES AN ACHIRAL
RESULT
meso
achiral catalyst
achiral
achiral
top
planar alkene
(cis)
50/50 but
IDENTICAL
both meso
bottom
achiral catalyst
achiral
meso
NOT A CHIRAL RESULT
3
INTERACTION OF ACHIRAL OBJECTS GIVES AN ACHIRAL
RESULT
achiral catalyst
achiral
top
planar alkene
(trans)
Racemic Mixture
50/50 Enantiomers
bottom
achiral catalyst
A RACEMIC MIXTURE IS NOT A CHIRAL RESULT (you do
not get a specific enantiomer)
4
INTERVENTION OF A CHIRAL INTERMEDIARY GIVES A
CHIRAL RESULT
not formed
specific binding
Enzyme (chiral) blocks top side
X
Me
Et
achiral alkene
one enantiomer
achiral catalyst or an achiral reagent
CHIRAL RESULT
5
INTERVENTION OF A CHIRAL INTERMEDIARY GIVES A
CHIRAL RESULT
not formed
X
alkene only fits one way into active site
Me
one enantiomer
Me
chiral catalyst
enzyme is the reagent
CHIRAL RESULT