CRYSTALLINE FORMS OF BETULIN:POLYMORPHISM OR PSEUDOPOLYMORPHISM?
T.N. Drebushchak, A. V. Mikhailovskaya, В. А. Дребущак, М. А. Михайленко, S. A. Myz, Т. П. Шахтшнейдер, Светлана А. Кузнецова
Abstract
By recrystallization with different solvents as well as decomposition of betulin ethanol solvate at room temperature a new crystalline form of the biologically active compound betulin, namely hemihydrate of betulin, is obtained. By single crystal X-ray diffraction data the crystal structure of hemihydrate of betulin is determined. By powder X-ray thermodiffraction and differential scanning calorimetry it is found that when hemihydrate of betulin is heated to melting, Н2О molecules are removed and solid-phase transformations occur, which are related to the formation of an intermediate crystalline form and an orthorhombic modification of betulin.