The polymorphic phase transformations in the chlorpropamide under pressure.

The crystal structure and vibrational spectra of the chlorpropamide have been studied by means of the X-ray diffraction and Raman spectroscopy at pressures up to 24.6 and 4.4 GPa, respectively. Two polymorphic phase transitions, between initial orthorhombic form-A and a monoclinic form-AI at P ∼ 1.2 GPa and, in additional, to another monoclinic form-AII at P ∼ 3.0 GPa, were observed. At pressures above 9.6 GPa, a transformation to the amorphous phase of chlorpropamide was revealed. The lattice parameters, unit cell volumes, and vibration modes as functions of pressure were obtained for the different polymorphic modifications of chlorpropamide.