Method for purifying 7-ketolithocholic acid by adopting silylation reagent

The invention relates to a method for purifying 7-ketolithocholic acid by adopting a silylation reagent. The method comprises steps as follows: a 7-ketolithocholic acid mixture is sufficiently dissolved in an organic solvent, the silylation reagent is added while stirred, and the mixture is slowly heated to 20-80 DEG C for a silylation reaction; after complete reaction, a solution is cooled to 0-4 DEG C, and precipitate is filtered and collected after completely separated out; inorganic acid with concentration of 2%-5% is added to the precipitate, the volume of the inorganic acid is 10-15 times of that of the inorganic acid, and the mixture is sufficiently stirred to form a turbid liquid; the turbid liquid is left to stand for 10-15 min at the temperature of 30-50 DEG C and cooled to 0-4 DEG C, and precipitate is filtered and collected after completely separated out; the precipitate is washed to be neutral by water, a mixed solvent is used for recrystallization and drying, and the purified 7-ketolithocholic acid is obtained. Through optimization of the reagent and parameters, double oxide impurities are effectively removed from the 7-ketolithocholic acid mixture. The provided method adopts simple steps, raw materials are easy to obtain, the effect is remarkable, and the method is suitable for large-scale production.