Citric Acid → Sildenafil Citrate

Participants

Reaction Steps

In a 0.5 L reactor equipped with mechanical stirrer, 370 ml acetone and 21.4 g wet sildenafil base were added. The mixture was heated to reflux. In a separate vessel, 8.95 g of citric acid was dissolved in 89.5 ml of acetone at room temperature. The solution was added dropwise. Upon completion of the addition, the reaction mixture was maintained at reflux for 1 hour, followed by 2 hours at room temperature. Sildenafil citrate precipitated during this period was filtered, and the cake was washed with acetone. 28.1 g wet sildenafil citrate was obtained and dried for 4 hours at 50° C. 25.5 g sildenafil citrate dry was obtained. (Yield of this step: 98.8%).

Provenance & Evidence