From racemic compounds through metastable to stable racemic conglomerates: crystallization features of chiral halogen and cyano monosubstituted phenyl glycerol ethers

All ortho-substituted Cl, Br, I, and CN phenyl glycerol ethers crystallize as racemic conglomerates, whereas meta- and para-derivatives constitute racemic compounds in the solid state. Only meta-halogen-substituted phenyl glycerol ethers, alongside the thermodynamically preferential heterochiral racemic compound phase, reveal the simultaneous existence of a conglomerate phase; the last state is metastable and turns into a stable racemic compound just in the crystalline phase.