Alendronic acid

Synthesis of Alendronic Acid: 1 mol of 4-aminobutyric acid was added to 1.5 mol of molten phosphoric acid at 95°C, followed by dropwise addition of 2 mol of phosphorus trihalide over 60 minutes. After the reaction mixture hardened, heating was continued for an additional 3 hours. The mixture was then hydrolyzed by adding 300 mL of water. Following cooling, the solution was poured into 1500 mL of methanol, and the resulting precipitate was collected to yield alendronic acid in 64.6% yield.