Abstract
DL-O-Acetylpantolactone was found to have two polymorphic forms. A form is the new crystals having a melting point of 20.7° and B form is the previously reported crystals3) having a melting point of 13.5°. Their racemic structure was examined from melting point diagrams, solubility diagrams, and infrared absorption spectra, and it was revealed that A form is a racemic compound and B form is a racemic congromerate. The solubilities of A and B forms in hexane were determined and thermodynamic properties of these forms were experimentally evaluated. The supersaturated solution of DL-O-acetylpantolactone was seeded with these forms and the optical isomers, and the specific rotations of the deposited crystals and the rotation angles of the filtrates were measured at appropriate time intervals. From these results, the relationship between optical resolution and racemic structures was discussed.
