INVESTIGATION AND APPLICATION OF CRYSTAL PHASE BEHAVIOR TO OBTAIN ENANTIOPURE CHEMICALS
An efficient method of creating and separating chiral molecules into enantiomers is a problem facing synthetic chemistry. Currently, most research is focused on creating enantiopure materials via asymmetric synthesis. The goal of this thesis project is to develop preferential crystallization techniques, specifically for crystalline materials, which form heterochiral (racemate) systems. Before this can be attempted, detailed information of the relative stability of possible crystal forms, including homochiral and heterochiral solid phase (known as conglomerate and racemate crystals), needs to be obtained.
This thesis focuses on several crystallization techniques that can be used to separate enantiomers using both one pot and two pot methods as well as a new method known as thermal ripening. Some systems merely use a seed crystal as the driving force for separation, while others use a slight offset of equilibria in an epimerizing system. Solubility differences in heterochiral and homochiral crystal forms also play a role in separations. By further understanding and establishing control over systems like these, we are gaining ground towards developing efficient methodology to separate chiral systems which will benefit both the industrial and research worlds.