Laux process

The Laux process is an industrial process for the production of aniline , in which nitrobenzene is reduced with the help of cast iron filings in the presence of water  , whereby the iron is oxidized and, depending on the reaction conditions, yellow iron (III) hydroxide oxide or black iron ( II, III) oxide is formed:

${\displaystyle \mathrm {2\ Fe+C_{6}H_{5}NO_{2}+2\ H_{2}O\longrightarrow FeO(OH)+C_{6}H_{5}NH_{2}} }$

${\displaystyle \mathrm {9\ Fe+4\ C_{6}H_{5}NO_{2}+4\ H_{2}O\longrightarrow 3\ Fe_{3}O_{4}+4\ C_{6}H_{5}NH_{2}} }$

The strongly exothermic reaction is catalyzed by chloride ions , which can be added in the form of aluminum chloride or iron (III) chloride . This differs this process from the otherwise similar Béchamp reduction , which uses hydrochloric acid .

The process was developed by the German chemist Julius Laux at the former IG Farben and has been in use since 1911. In order to be able to use the iron oxides that occur as by-products better as pigments , the process was optimized so that the production of several suitable iron oxide pigments became possible. The improved process was patented in 1928.

Individual evidence

1. ↑ Entry on iron oxide pigments. In: Römpp Online . Georg Thieme Verlag, accessed on April 12, 2018.
2. ↑ http://bayferrox.de/uploads/tx_lxsmatrix/laux-brochure_deutsch_compressed_02.pdf Production of iron oxide pigments using the Laux process