СOCRYSTALS OF BETULIN WITH DICARBOXYLIC ACIDS: SOLID STATE SYNTHESIS AND PROPERTIES

Cocrystals of betulin with dicarboxylic acids were obtained using mechanochemical treatment with the addition of small amounts of organic solvents. The formation of cocrystals was confirmed by powder X-ray diffraction, thermal analysis, and IR spectroscopy methods. The presence of a solvent, the optimal components ratio, and the duration of mechanical processing are important for the formation of cocrystals. In order to choose a solvent for preparing betulin cocrystals, the solvents of different polarity were compared. It has been shown that cocrystals are formed if solvents that can effectively dissolve dicarboxylic acid are used during mechanical processing. For comparison with the mechanochemical method, betulin cocrystals were obtained by heating a mixture of starting reagents. Morphological changes observed by scanning electron microscopy upon heating the reaction mixtures also indicate the formation of cocrystals. It has been shown that when cocrystals are dissolved in water, solutions with an increased concentration of betulin are formed, and an increase in the length of the aliphatic chain of the acid leads to a decrease in the rate of betulin release into the solution.