Acetic anhydride, acylation with

Friedel-Crafts Acylation. The Friedel-Crafts acylation procedure is the most important method for preparing aromatic ketones and thein derivatives. Acetyl chloride (acetic anhydride) reacts with benzene ia the presence of aluminum chloride or acid catalysts to produce acetophenone [98-86-2], CgHgO (1-phenylethanone). Benzene can also be condensed with dicarboxyHc acid anhydrides to yield benzoyl derivatives of carboxyHc acids. These benzoyl derivatives are often used for constmcting polycycHc molecules (Haworth reaction). For example, benzene reacts with succinic anhydride ia the presence of aluminum chloride to produce P-benzoylpropionic acid [2051-95-8] which is converted iato a-tetralone [529-34-0] (30). 

The use of activated anthranihc acid derivatives facUitates the preparation of the amides in those cases where the amines are either umeactive or difficult to obtain. Thus, reaction of (87-1) with phosgene gives the reactive the isatoic anhydride (89-1). Condensation of that with ortho-toluidine leads to the acylation product (89-2) formed with a simultaneous loss of carbon dioxide. This is then converted to the quinazolone (89-3) by heating with acetic anhydride. Reaction with sodium borohydride in the presence of aluminum chloride selectively reduces the double bond to yield the diuretic agent metolazone (89-4) [99]. 

Cyclic orthoesters derived from gem-diols offer a further route to alkenes. As part of a three-step conversion, they may be ring opened with hydrobromic acid to give O-acyl bromodeoxy compounds that undergo reductive elimination with copper-zinc. In this way, unsaturated nucleosides have been made by way of mixed 2y3,-bromo-2y3,-deoxy-3,/2, carboxyl-ates.174 A more direct route to alkenes from cyclic orthoesters involves heating in acetic anhydride together with zirconium oxide.175... 

Aminothiazole, with acetaldehyde, 42 to 2-mercaptothiazoie, 370 4-Aminothiazole-2,5-diphenyl, to 2,5 di-phenyl-A-2-thiazoline-4-one, 421 Ammothiazoie-A -oxide, 118 2-Aminothiazoles. 12 acidity of, 90 and acrylophenone, 42 acylations of, with acetic acid. 53 with acetic anhydride, 52 with acyl halides, 48 with chloracetyl chloride, 49 with-y-chlorobutyrylchloride, 50 with 0-chloropropionylchloride, 50 with esters, 53 with ethy acrylate, 54 with indoiyl derivatives, 48 with malonic esters, 55 with malonyl chloride, 49 with oxalyl chloride, 50 with sodium acetate, 52 with unsaturated acyl chloride, 49 additions to double bonds, 40 with aldehydes, 98 alkylations, with alcohols, 38 with benzyhydryl chloride, 34 with benzyl chloride, 80 with chloracetic acid, 33 with chloracetic esters, 33 with 2-chloropropionic acid, 32 with dialkylaminoalkyl halides, 33 with dimethylaminoethylchloride, 35 with ethylene oxide, 34, 38... 

Notice that deprotonations can be with BuLi or EtMgBr and that the acylation step works with acetic anhydride or with benzoyl chloride. As you can see, they are all highly stereoselective for the E-isomer, and the Julia olefination is one of the most important ways of making E double bonds connectively. 

Methylation with dimethyl sulfate in alkali gave the methyl derivatives 28 and 29. Although formaldehyde attacks at N-2, aldol condensation of 10 with benzaldehyde gave the 3a-hydroxybenzyl compound (30) which is dehydrated to the 2-acetyl-3-benzylidene compound (31) with acetic anhydride.27 With acid anhydrides the2-acyl derivatives are obtained however, with acid chlorides in pyridine or dimethylaniline the bicyclic ketone (32) is formed.31 Despite the occurrence of the bicyclic product (32) and the bicyclic intermediate (13) there is no evidence for the existence of a bicyclic tautomer of 10.37... 

The iV-acylated derivatives of maleic hydrazide, prepared from open-chain compounds, have been found to differ from acylated products obtained from maleic hydrazide acylations. Acylation of 4- or 5-substituted maleic hydrazides should permit the existence of two 0-acylated isomers. So far, only one isomer of unknown structure has been isolated from benzoylation of the 4-methyl analog. Maleic hydrazide and its 2-substituted analogs are 0-acylated with acetic anhydride, acyl halides, and 0,0-dialkylphosphorochlor-... 

The commercial process for the production of aspirin (or acetylsalicylic acid) involves a one-pot acylation reaction. Acetic anhydride reacts with salicylic acid in the presence of a small amount of sulfuric acid to produce acetylsalicylic acid and acetic acid. 

Several chemical methods are used. In one method the mixture of aniline and quinoline is acylated either with acetic anhydride or with sulfochloride. The aniline forms a derivative and the quinoline remains unaffected. A second method treats the mixture with sodium nitrite and sulfuric acid. The aniline is converted into the diazonium salt and the quinoline forms the sulfate. The solution is made alkaline and steam-distilled the diazonium salt changes to sodium phenoxide, and quinoline is distilled. In the third method, the mixture is separated by means of hydrochloric acid and zinc chloride. Quinoline chlorozincate, (C9H7N)2H2ZnCl4, is sparingly soluble in water and is separated from the soluble anihne salt. 

Various anhydrides show significant differences in reactivity. For instance, acetic anhydride reacted with starch in the presence of formamide, whereas phthalic anhydride required pyridine to react. This property was utilized in preparation of starch esters carrying two different acyl groups simultaneously.19181919 Mixed starch esters may also be prepared by using a mixture of various anhydrides in... 

AcP can be prepared easily by acylation of phosphoric acid with acetic anhydride or with ketene, and isolated as a fairly... 

Acylation of isobutylbenzene with acetic anhydride leads with high yield and selectivity to para-acetylisobutylbenzene (Eq. 9) which is an intermediate in the synthesis of ibuprofen, an important antiinflammatory drug [18]. With H/1 zeolite at 140 °C after 1 h the yield is 80 % with 96 % para selectivity. Acylation of tetra-lin with acid chlorides and different zeolites has also been studied [19], For this reaction again acetyl chloride is much less reactive than higher acid chlorides such as butanoyl or octanoyl chloride. The selectivity is in favor of the 2-substituted isomer (85-90%) and limited quantities of the 1 isomer (10-15%) are formed (Eq. 10). 

The reactions of alicyclic olefins with Se02 have been extensively investigated. Heating cyclopentene with Se02 in acetic anhydride (acylating oxidation) oxidizes it to much monoacetoxy- and a little diacetoxy-cyclopentene but in a bomb tube at 90-100° much diacetate and little monoacetate are obtained.225 Thus the second methylene group next to the double bond is more or less attacked according to the reaction conditions. 

Remarkable in this assortment of bases is the appearance of four formulas which, if correct, indicate the presence of alkaloids carrying a secondary (instead of the usual tertiary) amino group. Of these four bases, lucaconine (89) is definitely stated to be a secondary amine, although this function has not been characterized. Talatisamine (3), although formulated as a secondary amine, does not yield a crystalline A -acyl derivative with acetic anhydride or with benzoyl chloride, and fails to react with methyl iodide since only the base itself has been analyzed, the... 

The most prominent cellulose ester produced on the industrial scale is cellulose acetate. The reaction is usually performed with acetic anhydride and with sulfuric acid as a catalyst. To minimize heterogeneities, acetylation is allowed to run nearly to completion, and subsequently partial ester hydrolysis is initiated by the addition of water until a desirable solubility is achieved that corresponds to a DS of about 2.5. Such higher acyl homologues as propanoyl or butanoyl exhibit more thermoplastic properties. Many specialized esters such as chiral (-)-menthyloxyacetates, furan-2-carboxylates, or crown-ether-containing acylates have been prepared on the laboratory scale and characterized by NMR spectroscopy. Various procedures have been applied, using anhydrides and acyl chlorides as acylating agents in combination with such bases as pyridine, 4-dimethylaminopyridine (DMAP), or iV,iV -carbonyldi-imidazole. The substitution pattern of cellulose acetates has also been modified by postchemical enzymatic deacetylation. Cellulose 6-tosylates have been used as activated intermediates for nucleophihc substitution to afford 6-amino-6-deoxy, 6-deoxy, or 6-deoxy-6-halo-celluloses. ... 

Recently, Vedejs found that a mixture of tributylphosphine and acetic anhydride acylates alcohols faster than acetic anhydride with DMAP. However, the combination of acetic anhydride with DMAP and triethylamine proved superior. It is believed that the EtsN prevents HOAc from destroying the DMAP catalyst. 

AUcynes and allenes are formed by the acylation of nitrimines using acetic anhydride/pyridine with DMAP as catalyst (eqs 67 and 68). Nitrimines are prepared by nitration of ketoximes with nitrous acid. 

The dehydration of oximes by such reagents as phosphorus pentoxide, thionyl chloride, acetic anhydride, acyl chlorides, and phosphorus pentachloride is well known [26]. In effect, this dehydration procedure permits the conversion of aldehydes to nitriles with the same number of carbon atoms. A modification applicable only to the aromatic series makes use of boiling acetic acid as a dehydrating agent [27]. With other dehydrating agents, aliphatic aldehydes also may be converted to nitriles. Oximes may be converted readily to nitriles by an acid-catalyzed reaction with ortho esters [28]. 

Azlactones (anhydrides of a-acylamino acids) are formed by the condensation of aromatic aldehydes with acyl derivatives of glycine in the presence of acetic anhydride and anhydrous sodium acetate. Thus beiizaldehyde and acetyl-... 

Nitration in acetic anhydride, or in solutions of dinitrogen pentoxide or of other acyl nitrates in carbon tetrachloride, has been associated with a higher ratio of o- to 7)-substitution in the reactions of certain com-... 

These features serve to distinguish nitration in acetic anhydride from nitration in inert organic solvents. With other acyl nitrates less work has been done, and it is convenient to deal first with the case of benzoyl nitrate. 

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