Acetic anhydride-Ferric chloride

Ferric chloride-Acetic anhydride, FeCl3-(CH3C0)20. 

ESTERS Triphenylphosphine dibromide. Diisobutylaluminum hydride. Ferric chloride-Acetic anhydride. Magnesium bromide-Acetic anhydride. 

The alkylidene dimethone (dimedone) (I) upon boiling with glacial acetic acid, acetic anhydride, hydrochloric acid and other reagents frequently loses water and passes into a substituted octahydroxanthene or the anhydride (II), which often serves as another derivative. The derivatives (I) are soluble in dilute alkali and the resulting solutions give colourations with ferric chloride solution on the other hand, the anhydrides (II) are insoluble in dilute alkali and hence can easily be distinguished from the alkylidene dimedones (I). 

Hydrolysis. 1,1,1-Trichloroethane heated with water at 75—160°C under pressure and in the presence of sulfuric acid or a metal chloride catalyst decomposes to acetyl chloride, acetic acid, or acetic anhydride (54). However, hydrolysis under normal use conditions proceeds slowly. The hydrolysis is 100—1000 times faster with trichloroethane dissolved in the water phase than vice versa. Refluxing 1,1,1-trichloroethane with ferric and gallium chloride... 

Aromatic Ring Reactions. In the presence of an iodine catalyst chlorination of benzyl chloride yields a mixture consisting mostly of the ortho and para compounds. With strong Lewis acid catalysts such as ferric chloride, chlorination is accompanied by self-condensation. Nitration of benzyl chloride with nitric acid in acetic anhydride gives an isomeric mixture containing about 33% ortho, 15% meta, and 52% para isomers (27) with benzal chloride, a mixture containing 23% ortho, 34% meta, and 43% para nitrobenzal chlorides is obtained. 

However, this method is appHed only when esterification cannot be effected by the usual acid—alcohol reaction because of the higher cost of the anhydrides. The production of cellulose acetate (see Fibers, cellulose esters), phenyl acetate (used in acetaminophen production), and aspirin (acetylsahcyhc acid) (see Salicylic acid) are examples of the large-scale use of acetic anhydride. The speed of acylation is greatiy increased by the use of catalysts (68) such as sulfuric acid, perchloric acid, trifluoroacetic acid, phosphoms pentoxide, 2inc chloride, ferric chloride, sodium acetate, and tertiary amines, eg, 4-dimethylaminopyridine. 

Besides acetophenone, this reaction was also applied to p-chloro- andp-methoxyacetophenone, and even to an aliphatic ketone, acetone (although the yield was stated to be only half as large as that obtained from mesityl oxide, i.e., less than 30%, Dorofeenko and co-workers reported a 45% yield of 2,4,6-trimethylpyrylium perchlorate from acetone, acetic anhydride, and perchloric acid), and is the standard method for preparing pyrylium salts with identical substituents in positions 2 and 4. The acylating agent may be an anhydride in the presence of anhydrous or hydrated ferric chloride, or of boron fluoride, or the acid chloride with ferric chloride.Schneider and co-workers ... 

Dialkyl ethers can be cleaved by treatment with anhydrous ferric chloride in acetic anhydride.700 In this reaction both R groups are converted to acetates. Yields are moderate to high. Ethers can also be cleaved by the mixed anhydride acetyl tosylate 701... 

Regioselective debenzylation can be achieved by treatment with Lewis acids such as ferric chloride and S11CI4 or under acetolysis conditions with acetic anhydride and sulfuric acid, and several examples are depicted in Scheme 2.3.9 Acetolysis results in cleavage of the most acid-sensitive benzyl group. In general, primary benzyl ethers can be selectively acetolysed in the presence of secondary benzyl ethers. The regioselectivity of the reaction can be explained as follows sulfuric acid protonates acetic anhydride followed by the formation of an acetyl ion and acetic acid. The acetyl ion reacts with the sterically most accessible oxygen which is at... 

Hydrolysis of deferriferricrocin in 57% HI gives serine, glycine, alanine, ornithine and ammonia in the molar ratios 0.25 2.00 0.68 3.05 0.04 no alanine is found on hydrolysis in 6N HCI. Treatment with IN HCI at 100° for 15 min. gives substance with negative ferric chloride test. Re-acetylation with acetic anhydride and removal of O-acetyl affords a product with chromatographic properties of ferricrocin. 

That vomicine contains a phenolic hydroxyl group is not immediately obvious, for the alkaloid is insoluble in alcoholic alkali, does not give a ferric chloride color, and is not easily methylated or acetylated on the phenolic oxygen (187). Later work led to the isolation of what may be O-methylvomicine in small yield (191) and to O-acetylvomicine by the action of acetic anhydride sodium acetate (192). The presence of a phenolic grouping is evident, however, in vomicinic acid (CCXXXVIII ... 

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