Sodium Hydroxide → Alendronate sodium anhydrous

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Reaction Steps

A 250 ml flask was fitted with a mechanical stirrer, a thermometer, a dropping funnel, and a reflux condenser. The flask was charged with alendronic acid monohydrate (5 g, 0.019 mol) and aqueous ethanol. The aqueous ethanolic sodium hydroxide was added dropwise to the suspension of alendronic acid monohydrate in aqueous ethanol for 15 minutes at reflux with vigorously stirring. The mixture was then refluxed for additional 15 hours. The mixture was then cooled to room temperature with stirring. The solid was filtered, washed with absolute ethanol, then with absolute ethyl ether, and dried overnight in a vacuum oven (10-15 mm Hg, ambient temperature) to give 5.2 g of alendronate sodium, having crystalline Form H.

Provenance & Evidence