Acyl chlorides aromatic

Acyl chlorides, Aromatic hydrocarbons EfFenberger, F. et al., Angew. Chem. (Intern. Ed.), 1972, 11, 300 Addition of catalytic amounts (1%) of the acid (stronger even than perchloric acid) to mixtures of acyl chlorides and aromatic hydrocarbons causes more or less violent evolution of hydrogen chloride, depending on the reactivity of the Friedel-Crafts components. 

Trifluoromethanesulfonic acid, Acyl chlorides, Aromatic hydrocarbons, 0375 Trimethyl phosphate, 1318... 

TTie true ketones, in which the >CO group is in the side chain, the most common examples being acetophenone or methyl phenyl ketone, C HjCOCH, and benzophenone or diphenyl ketone, C HjCOC(Hj. These ketones are usually prepared by a modification of the Friedel-Crafts reaction, an aromatic hydrocarbon being treated with an acyl chloride (either aliphatic or aromatic) in the presence of aluminium chloride. Thus benzene reacts with acetyl chloride... 

Acyl cations (acylium ions) generated by treating an acyl chloride or acid anhydride with aluminum chloride attack aromatic rings to yield ketones The arene must be at least as reactive as a halobenzene Acyl cations are relatively stable and do not re arrange... 

Friedel-Crafts acylation of aromatic compounds (Section 12 7) Acyl chlorides and carboxylic acid anhydrides acylate aromatic rings in the presence of alumi num chloride The reaction is electrophil ic aromatic substitution in which acylium ions are generated and attack the ring... 

One of the most useful reac tions of acyl chlorides was presented in Section 12 7 Friedel-Crafts acylation of aromatic rings takes place when arenes are treated with acyl chlorides in the presence of aluminum chloride... 

Fnedel-Crafts acylation In the presence of alumi num chloride acyl chlorides and carboxylic acid an hydrides acylate the aromatic ring of phenols... 

Acylatmg agents such as acyl chlorides and carboxylic acid anhydrides can react with phenols either at the aromatic ring (C acylation) or at the hydroxyl oxygen (O acylation)... 

Friedel-Crafts acylation (Section 12 7) An electrophilic aro matic substitution in which an aromatic compound reacts with an acyl chloride or a carboxylic acid anhydride in the presence of aluminum chlonde An acyl group becomes bonded to the nng... 

Ketone formation can also be avoided if one of the functional acyl halogens ia phosgene is blocked. Carbamyl chlorides, readily obtained by the reaction of phosgene with ammonia or amines, are suitable reagents for the preparation of amides ia direct Friedel-Crafts acylation of aromatics. The resulting amides can be hydroly2ed to the corresponding acids (134) ... 

As a dibasic acid, malic acid forms the usual salts, esters, amides, and acyl chlorides. Monoesters can be prepared easily by refluxing malic acid, an alcohol, and boron trifluoride as a catalyst (9). With polyhydric alcohols and polycarboxyUc aromatic acids, malic acid yields alkyd polyester resins (10) (see Alcohols, polyhydric Alkyd resins). Complete esterification results from the reaction of the diester of maUc acid with an acid chloride, eg, acetyl or stearoyl chloride (11). 

H-Bond Acceptor (HBA) Acyl chlorides Acyl fluorides Hetero nitrogen aromatics Hetero oj gen aromatics Tertiary amides Tertiary amines Other nitriles Other nitros Isocyanates Peroxides Aldehydes Anhydrides Cyclo ketones Ahphatic ketones Esters Ethers Aromatic esters Aromatic nitriles Aromatic ethers Sulfones Sulfolanes... 

Triflates of aluminum, gallium and boron, which are readily available by the reaction of the corresponding chlorides with triflic acid, are effective Fnedel-Crafis catalysis for alkylation and acylation of aromatic compounds [119, 120] Thus alkylation of toluene with various alkyl halides m the presence of these catalysts proceeds rapidly at room temperature 111 methylene chloride or ni-tromethane Favorable properties of the triflates in comparison with the correspond mg fluorides or chlorides are considerably decreased volatility and higher catalytic activity [120]... 

Acylation with aromatic acid chlorides was believed to occur on carbon 91). The dibenzoylation of the enamine (113) with benzoyl chloride in the presence of triethylamine has, however, been shown to give a mixture of three products (92). The major components are the cis and Irons isomers of the O-acylated enamino ketone (Ola and b) and the minor isomer is the 2,6-diacylated enamine (132). 

The most important method for the synthesis of aromatic ketones 3 is the Friedel-Crafts acylation. An aromatic substrate 1 is treated with an acyl chloride 2 in the presence of a Lewis-acid catalyst, to yield an acylated aromatic compound. Closely related reactions are methods for the formylation, as well as an alkylation procedure for aromatic compounds, which is also named after Friedel and Crafts. 

The reaction is initiated by formation of a donor-acceptor complex 4 from acyl chloride 2, which is thereby activated, and the Lewis acid, e.g. aluminum trichloride. Complex 4 can dissociate into the acylium ion 5 and the aluminum tetrachloride anion 4 as well as 5 can act as an electrophile in a reaction with the aromatic substrate ... 

The sequential treatment of triazine derivative 990 with acyl chlorides and acetic anhydride and perchloric acid afforded (86H1031) thiadi-azolo[l, 2,4]triazinium perchlorates 991. On the other hand, cyclocondensation of 992 with organic acids gave 993 [82JHC1577 83JAP(K)58/180492] and 994 with aromatic aldehydes (84JIC552) (Scheme 183). 

Subsequently rates of benzoylation of a range of aromatics were determined under the same conditions (Table 105)407. The high negative entropy of activation is consistent with the high degree of ordering required for the polarised acyl chloride-aluminium chloride complex to be the electrophile. 

Dimsyl anion 88 reacts with esters of aromatic carboxylic acids and aliphatic acids which do not have a readily transferable proton, to give /5-ketosulfoxides114,133,138-141. There are not many cases in which acyl chlorides were used142,143. However, the reaction... 

In another nonelectrolytic process, arylacetic acids are converted to vi c-diaryl compounds 2A1CR2COOH —> ArCR2CR2Ar by treatment with sodium persulfate (Na2S20g) and a catalytic amount of AgNOs." Both of these reactions involve dimerization of free radicals. In still another process, electron-deficient aromatic acyl chlorides are dimerized to biaryls (2 ArCOCl —> ArAr) by treatment with a disilane RsSiSiRs and a palladium catalyst." " ... 

Wilkinson s catalyst has also been reported to decarbonylate aromatic acyl halides at 180°C (ArCOX ArX). This reaction has been carried out with acyl iodides, bromides, and chlorides. Aliphatic acyl halides that lack an a hydrogen also give this reaction, but if an a hydrogen is present, elimination takes place instead (17-16). Aromatic acyl cyanides give aryl cyanides (ArCOCN—> ArCN). Aromatic acyl chlorides and cyanides can also be decarbonylated with palladium catalysts. °... 

Other than energy considerations, on which there is little comparative data, the most important green role for photochemistry is in improving atom economy. Although only a preliminary research result, an excellent example of this is the avoidance of the need for stoichiometric amounts of Lewis acid catalysts in the synthesis of some acylated aromatic compounds. Benzoquinone can be reacted with an aldehyde under a sunlamp to yield an acylhydroquinone in up to 88% yield. The alternative procedure would involve reaction of an acyl chloride with hydroquinone and a... 

Chloroacylation of terminal aryl, alkyl or alkenyl alkynes [Le. the addition of RC(=0)-C1 across the CC triple bond] with aromatic acyl chlorides was catalysed by [IrCl(cod)(lPr)] (5 mol%) in good conversions (70-94%) in toluene (90°C, 20 h). Z-addition products were observed only, hitemal alkynes were umeactive. Surprisingly, a phosphine/[lr(p-Cl)(l,5-cod)]2 system under the same conditions provides decarbonylation products (Scheme 2.34) [117]. 

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