Anthraquinone process

{{Short description|Process for the production of hydrogen peroxide}}

The anthraquinone process, also called the Riedl–Pfleiderer process, is a process for the production of hydrogen peroxide, which was developed by IG Farben in the 1940s.{{cite journal |doi=10.1002/anie.200503779 |title=Hydrogen Peroxide Synthesis: An Outlook beyond the Anthraquinone Process |date=2006 |last1=Campos-Martin |first1=Jose M. |last2=Blanco-Brieva |first2=Gema |last3=Fierro |first3=Jose L. G. |journal=Angewandte Chemie International Edition |volume=45 |issue=42 |pages=6962–6984 |pmid=17039551 }} The industrial production of hydrogen peroxide is based on the reduction of oxygen, as in the direct synthesis from the elements. Instead of hydrogen itself, however, a 2-alkyl-anthrahydroquinone, which is generated before from the corresponding 2-alkyl-anthraquinone by catalytic hydrogenation with palladium is used. Oxygen and the organic phase react under formation of the anthraquinone and hydrogen peroxide. Among other alkyl groups (R) ethyl- and tert-butyl- are used, e.g., 2-ethylanthraquinone.

{{ cite encyclopedia |author1=Goor, G. |author2=Glenneberg, J. |author3=Jacobi, S. | title = Hydrogen Peroxide | encyclopedia = Ullmann's Encyclopedia of Industrial Chemistry | year = 2007 | publisher = Wiley-VCH | location = Weinheim | doi = 10.1002/14356007.a13_443.pub2 |isbn=978-3527306732 }}Römpp CD 2006, Georg Thieme Verlag 2006

File:Anthrachinone Process V1.svg

The hydrogen peroxide is then extracted with water and in a second step separated by fractional distillation from the water. The hydrogen peroxide accumulates as sump product. The anthraquinone acts as a catalyst, the overall reaction equation is therefore:

:{{chem2 | H2 + O2 -> H2O2 }}

If ozone is used instead of oxygen, dihydrogen trioxide can be produced by this method.{{cite journal | first = Božo |last=Plesničar | title = Progress in the Chemistry of Dihydrogen Trioxide (HOOOH) | journal = Acta Chimica Slovenica| year = 2005 | volume = 52 | pages = 1–12 | url = http://acta-arhiv.chem-soc.si/52/52-1-1.pdf }}