The invention relates to a preparation method of small-particle-size
bosentan, and belongs to the technical field of
raw material medicine preparation. According to a purifying method of the small-particle-size
bosentan, firstly, an
bosentan crude product is dissolved in
dichloromethane, and filtering is conducted; filter liquid is cooled to 0 to 5 DEG C, the temperature is maintained, and 50-60%
ethanol water with volume 1.8-3 times of that of the
solvent in the first step is added in a flowing mode; stirring speed is 220-250 rpm, the speed of adding the
ethanol water in a flowing mode is 10-15 ml / min, and after flowing adding is completed, stirring is conducted continuously for 4-5 hours; filtering is conducted, 50-60%
ethanol water is used for washing
filter cake, and
drying is conducted. The invention provides the preparation method of the small-particle-size bosentan. The prepared bosentan D90 can be controlled to be between 16.89 micrometers and 32.56 micrometers, and a
raw material medicine which can be used directly is provided for an bosentan preparation.