Alendronic Acid → 4-Aminobenzamide

Participants

Reaction Steps

The 4-aminobenzamide of alendronate sodium was prepared as follows. In a 500 mL beaker, 54 g (166 mmol) of sodium alendronate was dissolved in 150 mL of DI water with a pH adjusted to 11 with concentrated NaOH. Nitrobenzoyl chloride, 28 g (150 mmol), dissolved in 100 mL of THF, was added dropwise into the aqueous alendronate solution. The pH was kept at 11 with additional NaOH solution during the addition. After the addition was complete, the solution was stirred for another 2 hours at room temperature. THF was removed in vacuo, and the pH of the solution was adjusted to 4. The resulting precipitate, which was collected by filtration at room temperature, was primarily nitrobenzoic acid and was discarded. The solution was kept at 4° C. overnight, and the resulting precipitate was collected by filtration, washed with DI water, and dried. The resulting solid weighted approximately 56 g (86%).

Provenance & Evidence