Originally posted by Nicodem
Have you tried hydrogenating with Pd-C (5%)? That is the only way to make the work up easy and yield quantitative, since it only takes to filter off
the catalyst and rotavap. You might be worried about catalyst poisoning, but as far as I know sulfamides do not poison Pd. I might be wrong though,
but it is worth trying. If no poisoning occurs, most nitroaromatics can be reduced to amines with Pd-C load as low as 0.1-1 mol% at 60 PSI hydrogen.
Sodium dithionite should work, however you will never reach near quantitative yields since o-aminobenzenesulfamide should be quite soluble even in
cold water (you should check). I don't understand why would you want to neutralize with acetic acid in your proposed workup. Also, with reductions
with Na2S2O4 it is Na2CO3 that is used to maintain the reaction medium basic. I don't think using NaOH is a good idea. The reduction can also proceed
even without the carbonate and the remaining NH3/NH4Cl buffer might already be enough. In short, you must try it and see. |