Hydrochloric Acid → 5-Amino-1,3,4-thiadiazole-2-sulfonamide

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Reaction Steps

This is prepared by hydrolysis of the acetamide 2-acetylamino-1,3,4-thiadiazole-5-sulfonamide (acetazolamide). A slurry of 0.2 mol of acetazolamide in 600 mL of methanol is treated with 60 mL 12N HCl. This mixture is heated with stirring to reflux for 6 hours. Reaction progress is monitored using liquid chromatography. If reaction is not completed after 6 hours, another 30 mL of 12N HCl is added, and the mixture held at reflux for 2 hours. Methanol is then removed under reduced pressure. Product is recovered after raising the pH of the suspension to 7 by addition of NaOH at 0° C.-4° C., followed by filtration. Yield is between 85% and 98% of theoretical with 99% purity. KI =40 nM.

Provenance & Evidence