Can optical isomers be separated?
In principle, they can be, but the chemical properties of each optical antipode are the same.
What do I mean by the above?
The chemistry of an enantiomer is identical to the chemistry of the other enantiomer, in all achiral environments. The key word is achiral.
Suppose you have a mixture of
Let's further suppose that the added reagent
Typically, the diastereomers would be separated by fractional crystallization. And this is the world of fractional crystaliization to the
In recent years, chiral resolutions have become widespread. Here, instead of using crystallization, a chiral reagent is added that reacts preferentially with the one optical isomer (it can do so because this interaction is diasteromeric not enantiomeric). So, here one of the isomers is chemically transformed in a so-called chiral resolution. Because you chemically altered this isomer, it is a lot easier to separate from its original enantiomer.