Hydrochloric Acid → Terazosin Hydrochloride Anhydrous

Participants

Reaction Conditions

Reaction Steps

A slurry of 60 grams (0.25 mol) of 4-amino-2-chloro-6,7-dimethoxy-quinazoline, 55.3 g (0.3 tool) of 1-(2-tetrahydrofuroyl)piperazine and 175 grams of 2-methoxyethanol was heated, under a nitrogen atmosphere with mechanical stirring, to 120°-123° C. for eight hours. The slurry was then cooled to 70° C. and 140 ml of 3A 200 proof ethanol was added. The resulting mixture was heated to 60°-70° C. for one hour and then cooled to 0°-5° C. To the cooled solution was added 2.5 g of concentrated aqueous hydrochloric acid in 12 ml of 3A 200 proof ethanol. This mixture was kept at -5°-5° C. for one and one-half hours after which the precipitated solid was collected by filtration and washed with 50 ml of cold 3A 200 proof ethanol to yield 98.7 g (0.233 tool, 93%) of anhydrous 1-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-(2-tetrahydrofuroyl)piperazine hydrochloride of a previously unknown crystalline modification.

Provenance & Evidence