stereochemistry

stereoisomerism

a kind of isomerism where they have the same formula and same set of bonds but differ in the spatial arrangement of the atoms

enantiomers

mirror images that are not superimposable

50:50 mix of enantiomers

a racemate or a racemic mixture

resolution

separation of enantiomers

inversion

conversion of one isomer into the other

diastereomers

not mirror images - different physical, biological and chemical properties

configuration

2 steps

1. assign priorities

2. assign configuration

step 1

assign priorities in order of atomic number of the atom directly attached to the chiral centre

step 2

orient the molecule so that the group of lowest priority is pointing back draw an arc from the group of highest priority to the one of lowest

clockwise

R

anti clockwise

S

old method

mainly used for carbohydrates and amino acids

old letters

L and D

polarimetry

a method of analysis of mixtures of enantiomers relies on the use of plane polarised light

PPL

plane polarised light

clockwise - + enantiomer

D - dextrorotary

anti clockwise - - enantiomer

L laetorotatory

optical activity

a physical property of a chiral compound