Friedel Crafts with carboxylic acids

In the Friedel-Crafts acylation, carboxylic acid chlorides and carboxylic acid anhydrides are activated with stoichiometric amounts of A1C13 (Section 5.2.7). However, this activation is only possible in the presence of very weak nucleophiles such as aromatic compounds. Stronger nucleophiles would react with the A1C13 instead of the carboxylic acid derivative. If one wants to acylate such stronger nucleophiles—for example, alcohols or amines—with car-... 

Friedel-Crafts acylation. Carboxylic acids are converted into RCOCl with Me2Si(H)Cl and InCls. In the presence of an activated arene (e.g., an aryl ether) an aryl ketone is formed. A dual role is played by InCl3. 

Diaryl sulfones can be formed by treatment of aromatic compounds with aryl sulfonyl chlorides and a Friedel-Crafts catalyst. This reaction is analogous to Friedel-Crafts acylation with carboxylic acid halides (11-14). In a better procedure, the aromatic compound is treated with an aryl sulfonic acid and P2O5 in polypho-sphoric acid. Still another method uses an arylsulfonic trifluoromethanesulfonic anhydride (ArS020S02CF3) (generated in situ from ArS02Br and CF3S03Ag) without a catalyst. ... 

Acyl-transfer reactions are some of the most important conversions in organic chemistry and biochemistry. Recent work has shown that adjacent cationic groups can also activate amides in acyl-transfer reactions. Friedel-Crafts acylations are known to proceed well with carboxylic acids, acid chlorides (and other halides), and acid anhydrides, but there are virtually no examples of acylations with simple amides.19 During studies related to unsaturated amides, we observed a cyclization reaction that is essentially an intramolecular acyl-transfer reaction involving an amide (eq 15). The indanone product is formed by a cyclization involving the dicationic species (40). To examine this further, the related amides 41 and 42 were studied in superacid promoted conversions (eqs 16-17). It was found that amide 42 leads to the indanone product while 41... 

Although Friedel-Crafts acylation is well known with carboxylic acids, anhydrides, and acid halides, there are virtually no reports of Friedel-Crafts acylations being done with amides.63 These results demonstrate the application of distonic superelectrophiles to accomplish such a difficult... 

Our pioneering work in 1986[1] has shown that acid zeolites are efficient catalysts in the Friedel-Crafts acylation of toluene and xylene with carboxylic acids and constitutes a breakthrough in environmentally friendly fine chemistry replacing the conventional AICI3 method by a heterogeneous catalysts. Since this initial study, a tremendous amount of work has been performed in this area[2] and particularly, in recent years, the acetylation reaction, which is a field of research with large potential for the production of fine chemicals, has been intensively investigated. 

Chiche, B., Finiels, A., Gauthier, C., Geneste, P., Graille, J. and Pioch, D. Friedel-Crafts acylation of toluene and /7-xylene with carboxylic acids catalyzed by zeolites. J. Org. Chem., 1986, 51, 2128-2130. 

Primary, secondary, and tertiary carboxylic amides, carboxylic esters, and carboxylic acids are protonated by mineral acids or sulfonic acids at the carboxyl oxygen to a small extent (Figure 6.9). This corresponds to the activation discussed in Section 6.2.3. This activation is used in acid hydrolyses of amides and esters, in esterifications of carboxylic acids and in Friedel-Crafts acylations of aromatic compounds with carboxylic acids. 

Alkylation with Friedel-Crafts catalysts can promote production of soluble products from coal. This method Is currently not economical but the Information obtained has clarified several points. The extracts obtained from the alkylation of coal as described above, are black, shiny, solid substances which are not distillable and apparently still have very high molecular weights. They are very similar In their properties to the extracts which we have obtained previously by acylation of the same coals with carboxylic acid chlorides and aluminum chloride. 

Pure boron trifluoride is marketed as a compressed gas. It is utilized mainly in the organic industry as a Friedel-Crafts catalyst (Lewis acid) in the form of its complexes or addition compounds with, for example, ether, alcohols, carboxylic acids etc. or as a pure substance. 

The conventional method of preparation of these aromatic ketones is the homogeneous Friedel-Crafts acylation of aromatic hydrocarbons with carboxylic acid derivatives using Lewis acids (A1C13, FeCl3, BF3, ZnCl2, TiCl4) or Bronsted acids (polyphosphoric acid, HF). For this purpose, stoichiometric to excess amounts of the catalyst are required for the reaction to proceed (ref. 1). 

Pioneering and extensive work in this field was realized in 1985 [8] by use of exchanged Ce Y-zeolite as the catalyst for the Friedel-Crafts acylation of toluene (Eq. 3) and xylene with carboxylic acids. Different aspects of this initial work are of interest. Firstly, it shows that the mild acidity of zeolites is sufficient to effect the reaction, and, secondly, it shows that this reaction can be conducted with carboxylic acids and not the corresponding acid chlorides. Only the more lipophilic acids were found reactive whereas no acetylation occurs with acetic acid. The reaction with toluene (Table 1) is extremely para selective and more selective than a conventional aluminum chloride homogeneous process. The different reactivities reported in this paper are essentially because of differences between preferential adsorption of the substrates on the catalyst and not their intrinsic activity. 

Khodaei, M. M., Alizadeh, A., and Nazari, E. 2007. TfjO as a rapid and efficient promoter for the dehydrative Friedel-Crafts acylation of aromatic compounds with carboxylic acids. Tetrahedron Lett. 48 4199 202. 

Eirouzabadi, H., Iranpoor, N., and Nowrouzi, E. 2003. Solvent-free Friedel-Crafts acylation of aromatic compounds with carboxylic acids in the presence of trifluoroacetic anhydride and aluminum dodecatungstophosphate. Tetrahedron Lett. 44 5343-5345. 

Sarvari, M. H. and Sharghi, H. 2005. Solvent-free catalytic Friedel-Crafts acylation of aromatic compounds with carboxylic acids by using a novel heterogeneous catalyst system p-toluenesulfonic acid/graphite. Helv. Chim. Acta 88 2282-2287. 

Geneste and coworkers in 1986 reported that zeolites catalyzed Friedel-Crafits acylations in presence of a Ce + exchanged zeolite Y catalyzed the acylation of toluene and xylenes with carboxylic acids (Table 11.2) [42]. They also mentioned that only mild acidity is sufficient for Friedel-Crafts acylations which can be induced by means of zeolites catalysts. The reaction exhibited a very high para-selectivity. 

Poly phosphoric acid (PPA), a highly viscous liquid, is a useful reagent and catalyst in various rearrangements and isomerizations, especially in intramolecular reactions (24,25). Cyclization of various compovmds into aromatic rings and formation of heterocycles are the most important transformations where PPA usually ensures high yields. It is especially useful when Friedel-Crafts acylations are carried out with carboxylic acids. 

Metallo phthalocyanine units as dye components are fixed on lyotropic liquid crystalline systems based on poly(y-benzyl-L-glutamate). Phthalocyanines are introduced onto the liquid crystalline backbone of poly(y-benzyl-L-glutamate) as shown in Figure 17.13 via a Friedel-Crafts reaction of acid chloride of phthalocyanine tetra-carboxylic acid with the parent polymer [212]. Reactive metallo mesogens of the structure... 

Friedel-Crafts Reactions. Aluminum trifluoromethanesulfonate has been used for the Friedel-Crafts alkylation reaction of toluene with isopropyl and tert-butyl chlorides (eq 1), and for the acylation of benzene and toluene with acetyl and benzoyl chlorides in low to moderate yields. Intramolecular Friedel-Crafts acylation of an aromatic compound with Meldrum s acid has also been reported using catalytic amounts of Al(OTf)3. Acylation of 2-methoxynaphthalene with acetic anhydride has been reported using Al(OTf)3 and lithium perchlorate as an additive to afford the corresponding 6-acetylated adduct in 83% yield. Effective acylation of arenes with carboxylic acids has also been disclosed using polystyrene-supported Al(OTf)3. ... 

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... 

Friedel-Crafts acylation of fluorobenzene with thiophene-l-carboxylic acid gives the ketone 7. Nitration proceeds ortho to the fluoro group to give the intermediate Nucleophilic displacement by means of... 

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