METHOD FOR OBTAINING BETULINIC ACID Russian patent published in 2011 - IPC C07J53/00 C07J63/00 

FIELD: chemistry.

SUBSTANCE: before oxidation with a chromium (VI) compound, betulin is pre-dispersed in a donor coordination solution (acetone, pyridine, dimethylformamide, diethyl ether) while exposed to ultrasound, and the chromium (VI) compound (chromium oxide (Cr₂O₃) or potassium dichromate (K₂Cr₂O₇) or potassium chromate (K₂CrO₄) or pyridinium dichromate ((C₅H₅NH)₂Cr₂O₇ ^2-) or chloropyridinium chromate ((C₅H₅NH)⁺Cl₂O₃ ^-) in form of an aqueous solution is pre-deposited via sorption impregnation onto a solid substrate made from active aluminium oxide (Al₂O₃) or silica gel (SiO₂) with specific surface area of not less than 210 m/g. After the oxidation reaction, the solid substrate is removed after 1-120 minutes from the obtained dispersion of reaction products which is a mixture of betulonic and betulinic acid. The oxidation reaction products are then purified by diluting the dispersion with water 5-10 times at room temperature. The dispersion phase is removed by filtration and the obtained residue is washed 5-10 times with water at temperature 50-100°C, after which betulonic acid is reduced with sodium borohydride in an organic solvent to betulinic acid. The disclosed method enables to achieve betulinic acid output of up to 75-85% with respect to the starting betulin.

EFFECT: method has few steps and is short, avoids the use of a large amount of organic solvent, which reduces the cost of the end product and environmental pollution.

7 cl, 6 ex, 1 tbl