sulfonamide pKa

Hello, calculated (Marvin 5.12.2) pKa of methazolamide sulfonamide group is 10.06, while experimentally observed is about 7.3. For comparison, experimental pKa of acetazolamide is about 7.2, and calculation gives 6.93, which is fair close. These two compounds are very similar. Why are these differences?

Hi,

 

Thanks for reporting this bug.

The fix will be available in the 6.0 version.

 

Jozsi