Disappearing Conglomerates, Assessment of the Threat

A racemic compound has been identified for the system: (+) – (−) BINOL-OBn despite having been reported as a conglomerate. This heterochiral phase appears to be more stable than the conglomerate irrespective of the temperature. Its melting point exceeds by 20 °C that of the racemic eutectic. In conjunction with the revised phase diagram, the crystal structures of the racemic compound and of the pure enantiomer have been compared. In the structure of the racemic compound (Z′ = 3), hydrogen bonds can be found, whereas in the structure of the pure enantiomer (Z′ = 1) only π–π and van der Waals interactions are observed. The likelihood that a more stable racemic compound appears when processing a conglomerate (e.g., in preferential crystallization) is discussed.