[quangngaicity]

Hello all member.

I have to perform a reduction of an aromatic nitro group with ammonium formate and Pd/C in refluxing methanol (30 mmol scale). My colleague run that reaction before (1 mmol scale) and noticed a large amount of a white solid crystallizing on the walls of the condenser and obstructing it.
Could it be Ammonium Formate subliming (it should not, it should melt at 116 °C) or Ammonium carbonate forming from NH3, CO2 and water (formed by the reduction of the NO2 group)??
 Someone had the same problem and knows how to fix it?
Thanks in advance.

[Dan]

You can use H₂ instead of ammonium formate, which usually works at room temp.

There are many methods for reducing aromatic nitro groups - personally, I like Zn/CuSO₄ (e.g. 3j 16 in this paper, procedure in supporting info).

[orgopete]

I think you can turn down the heat. Reflux attains a level of heat, you can use a stirrer for mixing rather than the ebulation. I don't think you'll get as much ammonium salts collecting in the condenser.