3-Pyridineacetic acid → Risedronate

Participants

Reaction Conditions

Reaction Steps

3-Pyridine acetic acid (25 g) in 500 ml of chlorobenzene added to phosphorous acid (35.5 g). The reaction mixture was heated up to 85-90° C. To the reaction mixture phosphorous trichloride (58.97 g) was added slowly to obtain a yellowish rigid, thick mass. The reaction mass was cooled to ambient temperature. The solvent was decanted. Demineralized water (200 ml) was added to the reaction mass and refluxed azeotropically, to remove residual chlorobenzene. Filtered through hyflo bed while hot, washed with hot demineralized water. The reaction mass was cooled to 0-5° C., stirred for 1.0 hour, filtered the solid and washed to get risedronic acid (30.0 g, yield 58%) having purity of 83.98% by HPLC.

Provenance & Evidence