M. Yasui et al., DYNAMIC BEHAVIOR OF N-(2,4-DINITROPHENYL)-O-ANISIDINE CRYSTALS, Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals, 276, 1996, pp. 167
N-Picryl-p-toluidine (I) and N-(2,4-dinitrophenyl)-o-anisidine (II) cr
ystallize in two modifications, orange and red forms. The orange forms
of both compounds transform to the red forms on heating, while the re
d forms do not change thermally. The thermal transformation of I from
the orange form (Io) to the red (Ir) takes place through the liquid ph
ase. In the case of II, the transformation from the orange form (IIo)
to the red (IIr) occurred in the solid state over the wide temperature
range, 110 similar to 158 degrees C. In order to investigate the mech
anism of the phase transformation between these polymorphs, we carried
out the observation on the hot-stage with the microscope, the X-ray s
tructure analysis, measurement of temperature dependent powder diffrac
tions, and calorimetry. We also investigated the preliminary study on
the structure at high temperature.