STUDY ON POLYMORPHISM OF GOSSYPOL BY INFRARED SPECTROPHOTOMETRY AND X-RAY DIFFRACTION

The polymorphism of gossypol has been investigated by IR spectrophotometry and X-ray diffraction. Nine samples of gossypol crystallized from mixed solvent of ether, ethanol andwater (1:2:2), five samples from chloroform and ten samples from petroleum ether (bp 60～90℃) were determined. Significant differences in the infrared spectra of gossypol crystallized from three solvents were observed near 3500cm^-1. The spectrum of gossypol crystallized from mixed solvent of ether, ethanol and water (mp 183～184℃) showed bands at 3500 (sh), 3470, 3375cm^-1; that from chloroform (mp 198～199℃) at 3455, 3415(sh)cm^-1 and that from petroleum ether (mp213～214℃) at 3510, 3495, 3430(sh), 3410cm^-1. Moreover, the spectra of the three forms of gossypol showed slightly different bands at 780 and 600～400cm^-1.Gossypol crystallized from the three solvents showed the same infrared spectra after being crystallized from acetone.Significant differences in the X-ray diffraction pattern of gossypol crystallized from the three solvents were also observed. Angles, intensities and D-values of most of the X-ray diffraction peaks were listed.