AROMATIC ACID ANHYDRIDES

By interaction of the acid chloride (1 mol) and acid (1 mol) in the presence of pyridine (2 mols)  

ArCOCl + C5H5N + ArCOOH ----- ArCO—0—COAr + CjHjN.HCl 

AROMATIC ACID ANHYDRIDES The anhydrides of aromatic acids are prepared — 

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The choice of type of derivative should be based on whether the chloride or anhydride is aliphatic or aromatic, because this factoi largely determines the reactivity. Aliphatic acid chlorides are best converted into their anilides, as in 4 above aromatic acid chloride may be similarly converted into their anilides, or they may be converted into their amides by shaking with an excess of ammonia (p, 120). (M.ps., pp. 544-545.) Aliphatic acid anhydrides should be converted into their crystalline anilides, but aromatic acid anhydrides arc best hydrolysed to the acid, which can then be converted into one of the standard derivatives (p. 349). 

Almost insoluble in cold water. Higher alcohols (including benzyl alcohol), higher phenols (e.g., naphthols), metaformaldehyde, paraldehyde, aromatic aldehydes, higher ketones (including acetophenone), aromatic acids, most esters, ethers, oxamide and domatic amides, sulphonamides, aromatic imides, aromatic nitriles, aromatic acid anhydrides, aromatic acid chlorides, sulphonyl chlorides, starch, aromatic amines, anilides, tyrosine, cystine, nitrocompounds, uric acid, halogeno-hydrocarbons, hydrocarbons. 

The conversion of c>-hydroxyaryl ketones la to chromones 2a and/or coumarins 3a with aliphatic acid anhydrides in the presence of the sodium or potassium salt of the corresponding acid and the reaction between lb and aromatic acid anhydrides and the salt of the corresponding acid to form flavones 2b (Allan-Robinson) is called the Kostanecki-Robinson (K-R) reaction. ... 

Flavone formation is believed to proceed through a similar mechanism as the synthesis of chromones, albeit aromatic acid anhydrides and their corresponding salts are used. The first step is benzoylation of 12 to give the ester 14. Enolization and o-alkylation then affords the enolbenzoate 15. Enolbenzoate 15 then undergoes an acyl transfer to yield... 

With the discovery of benzyne formation by pyrolysis of phthalic anhydride, a new field was opened for the investigation of aryne reactions at high temperatures. A first concern was to determine the generality of aryne formation from aromatic acid anhydrides. Such syntheses could be of considerable significance because of the enormous quantities of aromatic mono- and polyanhydrides available from petroleum aromatics by oxidation. 

The condensation of aromatic acid anhydrides, e.g., phthalic anhydride, with aromatic hydrocarbons, e.g., napthalene, in the presence of ZnCl2 led to black polymer semiconductors of the polyacene quinone radical type [444, 445]. Resistivities in the order of 10 -10 °f2 cm were measured. High spin densities are characteristic [446]. An evaluation as active materials has not yet been performed. 

Aryl halides are frequently prepared from the corresponding aryldiazonium salts by diazotation procedures. However, diazonium salts can be subjected directly to very mild Heck arylation conditions, which deliver coupled products (entry 19). Preferably, the reaction is executed in nonaqueous solvents such as acetonitrile, acetone, or methylene chloride with sodium acetate as base and with palladiumbis(dibenzylideneacetone) as catalyst. Alternatively, a combination of the amine and f-butyl nitrite, in a mixture of acetic acid and monochloroacetic acid, can provide the desired product directly, which makes the isolation of a diazonium salt unnecessary (entry 20). " It is also possible to use aromatic acid anhydrides as oxidative addition precursors (entry 21). Clearly, anhydrides are very interesting starting materials for a number of Heck reactions due to price and absence of halide salt formation. 

Shmidt, A.F. and Smirnov, V.V. (2000) Use of aromatic acid anhydrides as arylation agents in the Heck reaction. Kinet. Catal., 41, 743. ... 

The conditions are compatible with a variety of other functionality including nitrile and ester, and both aliphatic and aromatic acid anhydrides may be used as the acylating reagent. 

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