Editing Acetic anhydride (section)

==Production==
Acetic anhydride was first synthesized in 1852 by the French chemist [[Charles Frédéric Gerhardt]] (1816-1856) by heating [[potassium acetate]] with [[benzoyl chloride]].<ref>Charles Gerhardt (1852) [https://books.google.com/books?id=MXkbAAAAMAAJ&pg=PA755jV6AQyks “Recherches sur les acides organiques anhydres”] (Investigations into the anhydrides of organic acids), ''Comptes rendus'' … , '''34''' :  755-758.</ref>

Acetic anhydride is produced by [[carbonylation]] of [[methyl acetate]]:<ref>{{citation | last1 = Zoeller | first1 = J. R. | last2 = Agreda | first2 = V. H. | last3 = Cook | first3 = S. L. | last4 = Lafferty | first4 = N. L. | last5 = Polichnowski | first5 = S. W. | last6 = Pond | first6 = D. M. | title = Eastman Chemical Company Acetic Anhydride Process | journal = Catal. Today | year = 1992 | volume = 13 | issue = 1 | pages = 73–91 | doi = 10.1016/0920-5861(92)80188-S}}</ref>
: {{chem2|CH3CO2CH3  +  CO  ->   (CH3CO)2O}}

The [[Monsanto process#Tennessee Eastman acetic anhydride process|Tennessee Eastman acetic anhydride process]] involves the conversion of methyl acetate to [[iodomethane|methyl iodide]]. Carbonylation of the methyl iodide produces [[acetyl iodide]], which reacts with acetate source to give the desired anhydride. [[Rhodium chloride]] in the presence of [[lithium iodide]] is employed as the catalyst. Because acetic anhydride is not stable in water, the conversion is conducted under anhydrous conditions.

To a decreasing extent, acetic anhydride is also prepared by the reaction of ketene ([[ethenone]]) with acetic acid at 45–55&nbsp;°C and low pressure (0.05–0.2&nbsp;bar).<ref name="Arpe">{{citation | last = Arpe | first = Hans-Jürgen | title = Industrielle organische Chemie: Bedeutende vor- und Zwischenprodukte | url = https://books.google.com/books?id=36kHHvzx6M8C&q=wacker+verfahren+essigs%C3%A4ureanhydrid&pg=PA200 | edition = 6th | publisher = Wiley-VCH | location = Weinheim | pages = 200–1 | isbn = 978-3-527-31540-6 | date = 2007-01-11 }}{{Dead link|date=July 2023 |bot=InternetArchiveBot |fix-attempted=yes }}.</ref>
:{{chem2|H2C\dC\dO + CH3COOH   ->   (CH3CO)2O}} 
:(Δ''H'' = −63 kJ/mol)

The route from acetic acid to acetic anhydride via ketene was developed by [[Wacker Chemie]] in 1922,<ref>{{citation | title = Milestones in the history of WACKER | url = http://www.wacker.com/cms/en/wacker_group/wacker_facts/history/history.jsp | publisher = Wacker Chemie AG | access-date = 2009-08-27}}.</ref> when the demand for acetic anhydride increased due to the production of [[cellulose acetate]].

Due to its low cost, acetic anhydride is usually purchased, not prepared, for use in research laboratories.