The present invention discloses a
parecoxib sodium impurity S, namely, N-{3-[(5-methyl-4-phenylisoxazol-3-yl)phenyl]
sulfonyl}propionamide, and an preparation method thereof, and belongs to the technical field of chemical
pharmacy. The method comprises the following steps: 5-methyl-3,4-diphenylisoxazole is used as a starting
raw material, and the
reaction conditions and an auxiliary
reagent are controlled to increase the ratio of a
sulfonyl chloride group connected to the meta-position of a phenyl ring at a 3-position of an
isoxazole ring; and an
amination reaction is performed, a
crystallization mother liquid is concentrated to
dryness, the obtained product is subjected to propionylation, and finally through preparative liquid
chromatography separation, the
parecoxib sodium impurity S is obtained. The high-purity
parecoxib sodium impurity S provided by the present invention can be used as an impurity
standard product in the detection and analysis of a finished product of
parecoxib sodium, so that the accurate positioning and
chemical composition determination of impurities in the detection and analysis of the finished product of the
parecoxib sodium are promoted, reinforcement of control of the impurities is facilitated, and the quality of the finished product of the
parecoxib sodium is further improved. The method provided by the invention has the advantages of cheap and easyraw materials, simple operation, good reproducibility, and an HPLC purity of 99.5% or more.