Anhydrides from ketenes

First prepared by C. F. Gerhardt from ben2oyl chloride and carefully dried potassium acetate (1), acetic anhydride is a symmetrical iatermolecular anhydride of acetic acid the iatramolecular anhydride is ketene [463-51-4]. Benzoic acetic anhydride [2819-08-1] undergoes exchange upon distillation to yield benzoic anhydride [93-97-0] and acetic anhydride. 

The production of acetic anhydride from acetic acid occurs via the intermediate formation of ketene where one mole of acetic acid loses one mole of water ... 

Four different methods (vapour-phase acetylation using acetic anhydride, acetylation using ketene gas, liquid phase acetylation using acetic anhydride/xylene, or neat acetic anhydride) were used to acetylate pine wood chips to a variety of WPGs for the production of MUF-bonded particleboards (Nilsson etal., 1988). Composite boards were exposed to unsterile soil in fungal cellar tests. Boards made from ketene acetylated chips were not found to be resistant to decay at the maximum WPG level achieved (17 %) with a liquid acetic anhydride modification, no decay was recorded at a WPG level of c. 18 % after 12 months exposure, whereas with a vapour-phase treatment at the same WPG, evidence for decay was found. 

Figure 17.14. Some unusual reactor configurations, (a) Flame reactor for making ethylene and acetylene from liquid hydrocarbons [Patton et al., Pet Refin 37(li) 180, (1958)]. (b) Shallow bed reactor for oxidation of ammonia, using Pt-Rh gauze [Gillespie and Kenson, Chemtech, 625 (Oct. 1971)]. (c) Sdioenherr furnace for fixation of atmospheric nitrogen, (d) Production of acetic acid anhydride from acetic acid and gaseous ketene in a mixing pump, (e) Phillips reactor for low pressure polymerization of ethylene (closed loop tubular reactor), (f) Polymerization of ethylene at high pressure.

Acetic Anhydride. Acetic anhydride is required as a process intermediate in acetylations. To obtain acetic anhydride from acetic acid, acetic acid is first pyrolyzed to ketene, which then reacts with recovered acetic acid to yield the anhydride. 

Fig. 10.16. Acetic anhydride from acetic acid ketene process. (Chem Systems Report No. 97/98- 7. Copyright Nexant Chem Systems, Inc. and used by permission of the copyright owner.)...

Acetaminophen, U5P. Acetaminophen. Af-Acetyl-p-aminophcnol. 4-hydroxyacetanilide. APAP (Panado. Tem-pra. Tylenol, etc.), may be prepared by reduction of p-ni-trophenol in glacial acetic acid, acetylation of p-aminophenol with acetic anhydride or ketene. or from p-hydroxy-acetophenonc hydrazonc. It occurs as a white, odorless. slightly bitter crystalline powder. It is slightly soluble... 

Acetic formic anhydride has been prepared by the reaction of formic acid with acetic anhydride and ketene, and of acetyl chloride with sodium formate. The present procedure is essentially that of Muramatsu. It is simpler than others previously described and gives better yields. It is easily adapted to the preparation of large quantities, usually with an increase in yield. Acetic formic anhydride is a useful intermediate for the formyl-ation of amines, amino acids, and alcohols, for the synthesis of aldehydes from Grignard reagents, and for the prejiaration of formyl fluoride. ... 

Other carboxylic acids give mixed anhydrides in this reaction,180-182 but these readily disproportionate to the pair of symmetrical anhydrides. This provides a method of obtaining good yields of acid anhydrides that are difficultly accessible by other routes. In Org. Syn. Williams and Krynitzky183 describe the preparation of hexanoic anhydride from the acid and ketene. 

Method for stabilising fibres formed from milk or soya bean protein using an acylating agent such as acetic anhydride and ketenes which may be in gaseous form... 

The preparation of acetic anhydride from acetic acid at a high temperature probably depends upon the primary formation of ketene and its reaction with acetic acid. 

Figure 14.8a shows a simplified flowsheet for the manufacture of acetic anhydride as presented by Jeffries. Acetone feed is cracked in a furnace to ketene and the byproduct methane. The methane is used as furnace fuel. A second reactor forms acetic anhydride by the reaction between ketene from the first reaction and acetic acid. 

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