Doxazosin → Doxazosin Mesylate

Participants

Reaction Steps

14.1 g of anhydrous methanesulfonic acid were added to a stirred mixture of 63.2 g of doxazosin, 125 ml of N-methyl-2-pyrrolidone and 500 ml of methanol in a 1 1 three-necked round-bottomed flask. During this time the internal temperature rose to 30° C., and a solution formed. After the addition of the methanesulfonic acid was complete, the reaction mixture was filtered into a second 1 1 three-necked round-bottomed flask. The filter was washed with 85 ml of methanol, and the combined filtrates were stirred for 5 h. After completion of the stirring time, the resulting precipitate was filtered off with suction and washed 3× with 25 ml of methanol each time. 125 g of moist doxazosin mesylate (modification D) were obtained. This corresponds to 70.4 g of dry substance and a yield of 91.8%.

Provenance & Evidence