Risedronate → Sodium hydrogen [1-hydroxy-1-phosphono-2-(pyridin-3-yl)ethyl]phosphonate

Participants

Reaction Conditions

Reaction Steps

A solution of sodium hydroxide (7.4 g, 1 eq.) in a mixture of water/ethanol (50%, v/v) (150 ml) was added drop-wise to a suspension of risedronic acid (50 g) and 5 g of EDTA (ca. 10% on a dry per-weight basis) in a mixture of water/ethanol (50%, v/v) (850 ml) at reflux temperature. The reaction mixture was stirred at reflux temperature until the pH was stable at about 4.2-4.7. The reaction mixture was cooled to a temperature of about 50° C. The precipitate was then filtered, washed twice with 50 ml mixture of water/ethanol (50%, v/v) and then with ethanol (1×50 ml) and dried over night at 50° C. to give 48.5 g (85%) of sodium risedronate white crystal substance of form B (water content by thermogravimetric analysis was 5.5%-7.5%). Less than 50 ppm of iron was found in the product by AES.

Provenance & Evidence