The reaction was first used by
Antoine Béchamp to reduce nitronaphthalene and
nitrobenzene to
naphthylamine and aniline, respectively.[3] The Béchamp reduction is broadly applicable to aromatic nitro compounds.[4][5]Aliphatic nitro compounds are however more difficult to reduce, often remaining as the
hydroxylamine. Tertiary aliphatic nitro compounds, however, are converted in good yield to the amine using the Béchamp reduction.[6]
The reduction proceeds in a multistep manner. First, the nitro group is reduced to
nitroso, which undergoes hydrogenation to a
hydroxylamino group prior to further reduction to the amine.[7]
Laux process
The traditional Béchamp reduction cogenerates gray-black iron oxides. The Laux process is based on the finding that the oxide coproduct is strongly affected by various additives, such as
ferrous chloride,
aluminium chloride, and even simply
sulfuric acid, which are added before heating the iron-nitrobenzene mixture. The innovations from Laux have shifted the emphasis of the Béchamp reduction for the manufacture of anilines to the production of valuable
iron oxide pigments.[8] The method is still effective for reduction of nitroaromatics.[9]
^McKetta, John J. (1989).
"Nitrobenzene and Nitrotoluene". Encyclopedia of Chemical Processing and Design: Volume 31 - Natural Gas Liquids and Natural Gasoline to Offshore Process Piping: High Performance Alloys. CRC Press. pp. 166–167.
ISBN978-0-8247-2481-8.