Synthesis of acetic anhydride

Preparation of acetic anhydride

Preparation of acetic anhydride from acetyl chloride and anhydrous sodium acetate

Acetic anhydride could be prepared by reacting acetyl chloride with anhydrous sodium acetate.

Preparation of acetic anhydride

Preparation of acetic anhydride

Commercially available crystallized sodium acetate contains three molecules of water (CH3COONa · 3H2O).  In order to dehydrate sodium acetate is placed in a shallow iron or nickel dish and heated over a free flame. Sodium acetate first melts and on further heating the mass solidifies. In order to remove the last portions of the water, the salt is heated further with a large flame, until the solidified mass melts for the second time.

To 70 grams of finely pulverized, anhydrous sodium acetate are placed in round bottom flask equipped with dropping funnel and distillation condenser connected with receiving flask (protected from moisture with calcium chloride tube). From the top 50 grams of acetyl chloride are added drop by drop from a separating funnel. As soon as the first half of the chloride is added, the reaction is interrupted for a short time, in order that the pasty mass may be stirred up with a glass rod. The second half of acetyl chloride is then added. If the addition of chloranhydride is too rapid some of it may distil over into the receiver. In such case, the fraction is poured back into the funnel and again allowed to act on the sodium acetate. Also, if the reaction is too rapid it can be cooled with ice-cold water. After all acetyl chloride has been added and the reaction is complete the acetic anhydride is distilled off from the reaction mixture. The crude distillate is finally purified by second distillation (boiling point of acetic anhydride is 138 °C) with 3 grams of finely pulverized anhydrous sodium acetate, which serves to convert the last portions of acetyl chloride into the acetic anhydride. The yield of acetic anhydride is about 50 grams.

Acetic anhydride can also by obtained from an anhydrous sodium acetate and phosphorus oxychloride. From practical point of view it is not necessary for the preparation of acetic anhydride isolate the acetyl chloride; it is better to allow acetyl chloride to act directly on an excess of the anhydrous sodium acetate, so that from the phosphorus oxychloride and anhydrous sodium acetate the acetic anhydride is directly obtained:

Practical organic chemistry. 1956, 372.

Preparation of acetic anhydride from acetic acid and oxalyl chloride

Accordingly acetic anhydride was prepared by placing 20 grams of dry acetic acid in a flask, fitted to a condenser and then dropping 20 grams of oxalyl chloride in the acetic acid. The water was removed from the acid by freezing it in a freezing mixture until there was just a little liquid left in the center. This liquid, which contains all of the water, was poured off, and the remaining acid allowed to melt again at room temperature. During the addition of oxalyl chloride the acid was gently refluxed, until all the reagent had been added and then continued until the evolution of hydrogen chloride gas ceased. Then the mixture of acid anhydride and acid chloride was separated by distillation in the fraction distillation flask. The yield obtained was 8 grams of the acetic anhydride, or 47 % of theory, b.p. 136-140° C. 5 grams of the acetyl chloride was also recovered b.p. 50-51° C, together with three grams of the unchanged acetic  acid.

Oxalyl chloride and oxalyl bromide as reagents in organic chemistry, L.H. Ulich, 23, 1918,


acetyl acetate



InChI Key


Canonical SMILES


MeSH Synonyms

acetic anhydride, acetic anhydride, 3H-labeled

Depositor-Supplied Synonyms

ACETIC ANHYDRIDE, Acetyl acetate, Acetic acid, anhydride, Acetanhydride, Acetic oxide, Acetyl oxide, Acetyl anhydride, Anhydride acetique, Ethanoic anhydride, 108-24-7, acetic acid anhydride, Acetyl ether, Essigsaeureanhydrid, Anidride acetica, Octowy bezwodnik, Azijnzuuranhydride, ethanoyl ethanoate, Ethanoic anhydrate, Acetic acid, 1,1′-anhydride, Ac2O, Caswell No. 003A, Anhydrid kyseliny octove, Azijnzuuranhydride [Dutch], Octowy bezwodnik [Polish], Anidride acetica [Italian], Anhydride acetique [French], Essigsaeureanhydrid [German], UNII-2E48G1QI9Q, CCRIS 688, HSDB 233, CHEBI:36610, Anhydrid kyseliny octove [Czech], WFDIJRYMOXRFFG-UHFFFAOYSA-N, EINECS 203-564-8, UN1715, EPA Pesticide Chemical Code 044007, BRN 0385737, Acetic anhydride-d6, diacetyl oxide, acetic-anhydride, acetic acetic anhydride, Acetic Anhydride, Acs, acetic acid acetyl ester, AC1L1PUO, DSSTox_CID_4395, SCHEMBL523, acetic acid-acetic anhydride, DSSTox_RID_77387, DSSTox_GSID_24395, (CH3CO)2O, MLS002454384, 110043_ALDRICH, 2E48G1QI9Q, 33214_RIEDEL, A6404_SIAL, AC1Q1L95, CHEMBL1305819, 91204_FLUKA, CTK4A5920, MolPort-000-872-007, 33214_SIAL, HMS3039J03, LTBB002529, 242845_SIAL, 320102_SIAL, 539996_SIAL, Tox21_200278, LS-456, STL264203, AKOS015915487, MCULE-9184217748, RL00342, UN 1715, NCGC00091802-01, NCGC00091802-02, NCGC00257832-01, Acetic anhydride [UN1715] [Corrosive], AN-42865, CAS-108-24-7, SMR001372001, Acetic anhydride [UN1715] [Corrosive], TR-001921, FT-0621765, FT-0638083, 4161-EP0930075A1, 4161-EP2269978A2, 4161-EP2269985A2, 4161-EP2269991A2, 4161-EP2269992A1, 4161-EP2269993A1, 4161-EP2269998A2, 4161-EP2270002A1, 4161-EP2270003A1, 4161-EP2270006A1, 4161-EP2270008A1, 4161-EP2270010A1, 4161-EP2270011A1, 4161-EP2270015A1, 4161-EP2270114A1, 4161-EP2272822A1, 4161-EP2272841A1, 4161-EP2272843A1, 4161-EP2272972A1, 4161-EP2272973A1, 4161-EP2274983A1, 4161-EP2275105A1, 4161-EP2275404A1, 4161-EP2277848A1, 4161-EP2277872A1, 4161-EP2277878A1, 4161-EP2277880A1, 4161-EP2280000A1, 4161-EP2280012A2, 4161-EP2281563A1, 4161-EP2281817A1, 4161-EP2281818A1, 4161-EP2284150A2, 4161-EP2284151A2, 4161-EP2284152A2, 4161-EP2284153A2, 4161-EP2284155A2, 4161-EP2284156A2, 4161-EP2284157A1, 4161-EP2284159A1, 4161-EP2284160A1, 4161-EP2284164A2, 4161-EP2284165A1, 4161-EP2284169A1, 4161-EP2284174A1, 4161-EP2287140A2, 4161-EP2287148A2, 4161-EP2287150A2, 4161-EP2287153A1, 4161-EP2287161A1, 4161-EP2287162A1, 4161-EP2287165A2, 4161-EP2287166A2, 4161-EP2287167A1, 4161-EP2289868A1, 4161-EP2289885A1, 4161-EP2289887A2, 4161-EP2289888A2, 4161-EP2292228A1, 4161-EP2292576A2, 4161-EP2292610A1, 4161-EP2292615A1, 4161-EP2292617A1, 4161-EP2292620A2, 4161-EP2292624A1, 4161-EP2295055A2, 4161-EP2295402A2, 4161-EP2295406A1, 4161-EP2295407A1, 4161-EP2295411A1, 4161-EP2295414A1, 4161-EP2295415A1, 4161-EP2295419A2, 4161-EP2295423A1, 4161-EP2295437A1, 4161-EP2295439A1, 4161-EP2295441A2, 4161-EP2295503A1, 4161-EP2298312A1, 4161-EP2298731A1, 4161-EP2298735A1, 4161-EP2298736A1, 4161-EP2298743A1, 4161-EP2298746A1, 4161-EP2298766A1, 4161-EP2298768A1, 4161-EP2298772A1, 4161-EP2298775A1, 4161-EP2298778A1, 4161-EP2298780A1, 4161-EP2301911A1, 4161-EP2301922A1, 4161-EP2301928A1, 4161-EP2301933A1, 4161-EP2305219A1, 4161-EP2305250A1, 4161-EP2305633A1, 4161-EP2305637A2, 4161-EP2305649A1, 4161-EP2305651A1, 4161-EP2305655A2, 4161-EP2305657A2, 4161-EP2305663A1, 4161-EP2305666A1, 4161-EP2305672A1, 4161-EP2305673A1, 4161-EP2305675A1, 4161-EP2305677A1, 4161-EP2305682A1, 4161-EP2305684A1, 4161-EP2305687A1, 4161-EP2305689A1, 4161-EP2305808A1, 4161-EP2308479A2, 4161-EP2308510A1, 4161-EP2308828A2, 4161-EP2308833A2, 4161-EP2308838A1, 4161-EP2308839A1, 4161-EP2308841A2, 4161-EP2308854A1, 4161-EP2308861A1, 4161-EP2308873A1, 4161-EP2308879A1, 4161-EP2308880A1, 4161-EP2311453A1, 4161-EP2311464A1, 4161-EP2311494A1, 4161-EP2311804A2, 4161-EP2311806A2, 4161-EP2311808A1, 4161-EP2311814A1, 4161-EP2311824A1, 4161-EP2311827A1, 4161-EP2311829A1, 4161-EP2311834A1, 4161-EP2311842A2, 4161-EP2314295A1, 4161-EP2314576A1, 4161-EP2314585A1, 4161-EP2314590A1, 4161-EP2314593A1, 4161-EP2316825A1, 4161-EP2316826A1, 4161-EP2316827A1, 4161-EP2316836A1, 4161-EP2371805A1, 4161-EP2371831A1, 4161-EP2374454A1, 4161-EP2374786A1, 4459-EP2270003A1, 4459-EP2283898A1, 4459-EP2298746A1, 4459-EP2305647A1, 4459-EP2314576A1, 4459-EP2314586A1, 12410-EP2270010A1, 12410-EP2270015A1, 12410-EP2272839A1, 12410-EP2272840A1, 12410-EP2275413A1, 12410-EP2295410A1, 12410-EP2295441A2, 12410-EP2298776A1, 12410-EP2298780A1, 12410-EP2298783A1, 12410-EP2301930A1, 12410-EP2305679A1, 12410-EP2305682A1, 12410-EP2305808A1, 12410-EP2308861A1, 12410-EP2308879A1, 12410-EP2311829A1, 12410-EP2311842A2, 12410-EP2314295A1, 12410-EP2316974A1, 72709-EP2292624A1, 72709-EP2308492A1, 4-02-00-00386 (Beilstein Handbook Reference), A801828, 3B4-2737, I14-6212, InChI=1/C4H6O3/c1-3(5)7-4(2)6/h1-2H

Removed Synonyms

silane, acetyltrimethyl-, acetic anhydride, 3H-labeled, CID7918, A1668, A2036, C031800, 16649-49-3

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  1. Lewis

    I found it rather difficult to seperate the acetic chloride from the end mixture, even after distillation Any help?

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