Reduction of Nitro Compounds to Amines: Experimental Procedures

• Reduction with molecular hydrogen:To a solution of the nitro compound in a suitable solvent, e.g. water, alcohols, dioxane, and alkanes, is added Raney nickel. The vigorously stirred mixture is hydrogenated at room temperature in a hydrogen atmosphere of approximately 100 $\text{bar}$.
• Reduction with hydrazine: A solution of the nitro compound and hydrazine hydrate in alcohol is treated slowly at 30$\text{°C}$ - 40$\text{°C}$ with a suspension of Raney nickel in alcohol. Progress of the reaction is easily monitored by observing the development of nitrogen..
• Reduction with tin and hydrochloric acid: The nitro compound is heated with finely granulated tin and half-concentrated hydrochloric acid. The precipitated amine hydrochloride is transformed into the free base with KOH and purified. This procedure is used for qualitative analysis in the laboratory.