Acetanilide
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Acetanilide is the organic compound with the formula Template:Chem2. It is the N-acetylated derivative of aniline.<ref name=Ullmann>Template:Cite encyclopedia</ref> It is an odourless solid chemical of leaf or flake-like appearance. It is also known as N-phenylacetamide, acetanil, or acetanilid, and was formerly known by the trade name Antifebrin.
Preparation and propertiesEdit
Acetanilide can be produced by reacting acetic anhydride with aniline:<ref name=Ullmann/>
- C6H5NH2 + (CH3CO)2O → C6H5NHCOCH3 + CH3COOH
The preparation used to be a traditional experiment in introductory organic chemistry lab classes,<ref>See, e.g., Template:Citation; Template:Citation: the latter preparation includes the reduction of nitrobenzene to aniline.</ref> but it has now been widely replaced by the preparation of either paracetamol or aspirin, both of which teach the same practical techniques (especially recrystallization of the product) but which avoid the use of aniline, a suspected carcinogen.
Acetanilide is slightly soluble in water, and stable under most conditions.<ref name="MSDS"/> Pure crystals are plate shaped and appear colorless, white, or in between.
ApplicationsEdit
Acetanilide is used as an inhibitor of hydrogen peroxide decomposition and is used to stabilize cellulose ester varnishes.<ref name=Ullmann/> It has also found uses in the intermediation in rubber accelerator synthesis, dyes and dye intermediate synthesis, and camphor synthesis.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Acetanilide is used for the production of 4-acetamidobenzenesulfonyl chloride, a key intermediate for the manufacture of the sulfa drugs.<ref>Template:Cite book</ref>
In the 19th century acetanilide was one of a large number of compounds used as experimental photographic developers.
During the same period of time, acetanilide was introduced into medical practice as a fever-reducing agent under the name Antifebrin.<ref>Template:Cite journal</ref> It was one of the first aniline derivatives found to possess analgesic and antipyretic properties. However, its use was later discontinued due to toxic side effects, including methemoglobinemia, which led to cyanosis.<ref>Template:Cite journal</ref>
Acetanilide derived herbicides have been used since the 1960s or earlier. These include alachlor, metolachlor and xylachlor.<ref>OWEN, M. D. K. (1982). A Comparison Of The Herbicidal Activity Of Several Chloroacetamides And Their Effects On Protein Synthesis In Carrot And Soybean Cell Suspension Cultures (Order No. 8218534). Available from ProQuest Dissertations & Theses Global. (303227220). Retrieved from https://www.proquest.com/dissertations-theses/comparison-herbicidal-activity-several/docview/303227220/se-2</ref>
Pharmaceutical useEdit
Acetanilide was the first aniline derivative found to possess analgesic as well as antipyretic properties, and was quickly introduced into medical practice under the names of Antifebrin by A. Cahn and P. Hepp in 1886.<ref>Template:Citation.</ref> But its (apparent) unacceptable toxic effects, the most alarming being cyanosis due to methemoglobinemia and ultimately liver and kidney damage,<ref name="Ax&Brodie">Template:Citation.</ref> prompted the search for supposedly less toxic aniline derivatives such as phenacetin.<ref name=pmid17227290>Template:Citation.</ref> After several conflicting results over the ensuing fifty years, it was established in 1948 that acetanilide was mostly metabolized to paracetamol (acetaminophen) in the human body, and that it was this metabolite that was responsible for the analgesic and antipyretic properties.<ref name="Ax&Brodie"/><ref>Multiple sources:
- Template:Citation.
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- Cahn, A., & Hepp, P. (1886). Das Antifebrin, ein neues Fiebermittel. Centralbl. Klin. Med.
- Brodie, B. B., & Axelrod, J. (1948). The fate of acetanilide in man. Journal of Pharmacology and Experimental Therapeutics, 94(1), 29–38.</ref> The observed methemoglobinemia after acetanilide administration was ascribed to the small proportion of acetanilide that is hydrolyzed to aniline in the body.