The invention relates to the technical field of pharmaceutical
chemistry, particularly relates to a method of pharmaceutical synthesis, and specifically relates to a preparation method of
sodium ibandronate. To overcome the disadvantages of high content of chlorides and phosphites in
sodium ibandronate prepared by a conventional preparation method of
sodium ibandronate, the preparation method of sodium ibandronate with extremely low content of chlorides and phosphites is provided. In the preparation method, 3-(N-methylpentylamino) propionic acid
hydrochloride,
phosphorus trichloride and
phosphorous acid are employed as raw materials and reacted in a
chlorobenzene solvent, so as to obtain sodium ibandronate with extremely low content of the chlorides and the phosphites. The obtained sodium ibandronate can not only meet
impurity control standards of the chlorides and the phosphites in a sodium ibandronate
crude drug, but also prevent low yield, long period and huge harm to
human body and environment which are brought by a lot of refining steps.