[itansif]

The question:
Saccharin has a pKa of ~2.
(a) Would you expect it's N-atom to be basic?
(b) Would you expect it's N-H proton to be acidic? (use resonance diagrams to explain)
(c) Would you expect the pH of water to change if you dissolved sacccharin (not sodium saccharin) in it?

I would expect the N-atom to have reduced basicity due to the sulfonamide/carbonyl resonance, as the NBP would be less available.
I would expect the N-H proton to be quite acidic - two electron withdrawing atoms on either side of it. Also the CB is resonance stabilised, with four possible resonance "states".
However - (c) confuses me as literature says that the acid form of saccharin (unionised) is insoluble, and that the salt is soluble. I don't understand how this can be if the proton is so acidic - on contact with water wouldn't it immediately ionise (changing the pH) into the soluble, ionic form?