| This study investigated the crystallization of two organic crystals, namely 2,4,6,8,10,12-hexanitrohexaazaisowurzitane (HNIW or CL20) and p-hydroxyacetanilide (acetaminophen). Both have paramount roles in their field of use, the former in the energetics industry and the latter, in the pharmaceutical arena.; The physico-chemical properties of CL20 available from different commercial sources and those grown in our laboratories were characterized and compared. These properties were impurity levels using Liquid Chromatography (LC) (where it was established that a scale-up using semi-preparative technique can be used as a separation tool), particle size/shape using Scanning Electron Microscope (SEM), particle size-dependent defect density distributions using X-ray Analyzer for Particles (XAPS), mosaicity and degree of crystallinity using Wide Angle X-ray Diffraction (WAXD). Further, this study demonstrated through a developed X-ray Diffraction (XRD) technique that commercially available CL20 materials are mixtures of polymorphs which otherwise are accepted as the epsilon polymorph within the limits of the precision of conventional techniques, including Fourier Transform Infrared Spectroscopy (FTIR). The XRD technique developed has allowed the correlation of single crystal and powder diffraction data to determine the polymorphic content in CL-20.; The solvents selected principally on the basis of their polarity affected the degree of crystallinity and mosaicity of re-crystallized CL20 and acetaminophen. Here, it was shown that by understanding the solvent parameters, the proper choice of chemical(s) (solvents and additives) could lead to a target CL20 polymorph mixture. This study validates the XRD methodologies developed for CL-20 to qualitatively screen the phases (or impurities) present, as to be also applicable to other important organic crystals, including acetaminophen. |
PDF Full Text Request