Friedel and Crafts synthesis

The halogenated ketones of the aromatic series may be prepared, like those of the aliphatic series, by the action of the halogens on the corresponding ketones. Some may be obtained by the Friedel and Craft synthesis, that is, by condensing an aromatic hydrocarbon with an aliphatic halogen acid in presence of anhydrous aluminium chloride. 

The formation of anthraquinone from phthalic anhydride and benzene by the Friedel and Crafts synthesis is conducted in the presence of aluminum chloride.58 Ortho-benzoyl benzoic acid is first formed and then... 

Friedel and Crafts Synthesis,—In the presence of anhydrous aluminium chloride, aliphatic halogen compounds react with aromatic hydrocarbons and form condensation-products as the result of the elimination of halogen hydride. Thus, when a mixture of benzene and aluminium chloride is treated with methyl chloride, toluene is formed —... 

The Friedel and Crafts synthesis is of particular value in the preparation of certain classes of hydrocarbons. Diphenyl-methane is best prepared in this way from benzylchloride, C6H5CH2CI —... 

Diphenylmethane, (C6H5)2CH2, is best prepared from benzyl chloride, C6H5CH2CI, and benzene by the Friedel and Crafts synthesis. It melts at 26° and boils at 262°. Homo-logues of this compound can be prepared from aldehydes and aromatic hydrocarbons by the action of sulphuric acid. Thus, aldehyde or acetal and benzene when shaken with sulphuric acid give diphenyl-methyl-methane (unsymmetrical diphenylethane) ... 

Triphenylmethane, (C6H5)3CH, is an important hydrocarbon on account of its relation to the triphenylmethane dyes. It is prepared from chloroform and benzene by the Friedel and Crafts synthesis —... 

Anthracene may be prepared by the Friedel and Crafts synthesis from benzene and acetylene tetrabromide —... 

From a study of the structure of many substances formed as the result of the introduction of substituents into aromatic compounds, certain general conclusions of great importance can be drawn. It has been pointed out that aromatic compounds yield substitution-products when treated with sulphuric acid, nitric acid, chlorine, and bromine. Under certain conditions iodine can also be introduced directly. Alkyl, acyl, and other radicals can be introduced by means of the Friedel and Crafts synthesis. In all these cases the position in the molecule taken by the entering atom or group is determined by the nature of the atom or group already present. The facts established lead to the following rules —... 

The earliest reported reference describing the synthesis of phenylene sulfide stmctures is that of Friedel and Crafts in 1888 (6). The electrophilic reactions studied were based on reactions of benzene and various sulfur sources. These electrophilic substitution reactions were characterized by low yields (50—80%) of rather poorly characterized products by the standards of 1990s. Products contained many by-products, such as thianthrene. Results of self-condensation of thiophenol, catalyzed by aluminum chloride and sulfuric acid (7), were analogous to those of Friedel and Crafts. 

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. 

In 1863 Friedel and Crafts were the first to use metalorganic compounds to synthesise silicone monomers. Industiy focused on organomagnesium synthesis (the Grignard technique), in which alkyl- or arylhalogenide interacts with metallic magnesium to form organomagnesium compounds ... 

Friedel and Crafts (who later became the president of MIT) discovered this reaction in 1879, but seven years before, Baeyer and his colleagues carried out very similar reactions using aldehydes as the alkylating agent and strong acids as catalysts. These reactions, like the Friedel-Crafts reaction, proceed through carbocation intermediates. Consider the synthesis of DDT (l,l,l-trichloro-2,2-di(p-chlorophenyl)ethane)) ... 

The structure of phenolphthalein has been established by its synthesis from diphenylphthalid, which is prepared from phthalyl chloride and benzene by the Friedel and Crafts reaction —... 

PPS was discovered by Friedel and Crafts [2]. In 1967, Edmonds and Hill of Phillips Petroleum Company developed a method for producing PPS through the synthesis of / -dichlorobenzene and sodium sulfide [3]. The commercial production of PPS started in 1972. In addition, varieties of PPS, which are shown in Figure 5.1, have been described [4]. 

The model compounds used to explore the chemistry of imidines can be divided into two basic groups, the diphenylphthalides and the benzylidene phthalides. The first reported synthesis of 3,3-diphenyl-phthalide [1] was by Friedel and Crafts in 1877. Their method involved reacting phthaloyl chloride with benzene in the presence of aluminum chloride. 

Friedel-Crafts synthesis TALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15)... 

Anthraquinone dyes are derived from several key compounds called dye intermediates, and the methods for preparing these key intermediates can be divided into two types (/) introduction of substituent(s) onto the anthraquinone nucleus, and (2) synthesis of an anthraquinone nucleus having the desired substituents, starting from benzene or naphthalene derivatives (nucleus synthesis). The principal reactions ate nitration and sulfonation, which are very important ia preparing a-substituted anthraquiaones by electrophilic substitution. Nucleus synthesis is important for the production of P-substituted anthraquiaones such as 2-methylanthraquiQone and 2-chloroanthraquiaone. Friedel-Crafts acylation usiag aluminum chloride is appHed for this purpose. Synthesis of quinizatia (1,4-dihydroxyanthraquiQone) is also important. 

They avoided the obvious Friedel-Crafts synthesis of (33), presumably to avoid the separation of o and p isomers, and used instead either Grignard route to (34),... 

Durene, pentamethyl benzene and hexamethyl benzene have usually been prepared from benzene or one of its methylated derivatives by the Friedel-Crafts synthesis.1 Durene has been made from bromine derivatives of methylated benzenes by the Fittig reaction.2 It has also been obtained in 20 per cent yield by passing methyl alcohol and acetone vapors over heated alu-... 

B. The Phthaleins.—If two molecules of a phenol and one molecule of phthalic anhydride are caused to interact under the conditions which prevail during the Friedel-Crafts synthesis (Chap. IX. p. 342), the tendency of the ketone first formed to combine with a second molecule of the phenol outweighs condensation to the anthraquinone derivative in this way are formed the phthaleins, discovered by Baeyer in 1871. This process may be discussed by taking phenolphthalein as an example. 

Aluminium Chloride.—For the success of a Friedel-Crafts synthesis it is essential that the quality of the aluminium chloride used as catalyst should be beyond reproach. Commercial preparations are often partially decomposed and unfit for use in consequence of the entrance of moisture into insufficiently closed containers. In order to make sure, a small sample should be heated over a flame in a test tube held obliquely the whole, or at least the bulk, of the chloride should sublime. Preparations which are not too seriously decomposed can be made fit for use by resublimation. 

On account of the great reactivity of the substances taking part in the reaction, the choice of a solvent in the Friedel-Crafts synthesis is limited. The most important are carbon bisulphide, well purified petrol ether, chlorobenzene, and nitrobenzene. 

Friedel-Crafts alkylation of 2,5-dimethylthiophene with f-butyl chloride and A1C13 gave only the mono-r-butylated product (49) and none of the expected di-f-butylated thiophene (50). In order to facilitate di-r-butylation at positions 3 and 4, the substituents at 2 and 5 were tied back in the thiophenophane (51). This on alkylation gave, unexpectedly, the rearranged mono-f-butyl derivatives (52 30%) and (53 57%), and the di-f-butyl derivative (54 12%). The structures of the products were proved by NMR, Raney nickel desulfurization and independent synthesis (75T2551). One other such isomerization under Friedel-Crafts conditions had been previously reported (65JOC1058) 2,5-di-f-butylthiophene isomerizing to 2,4-di-f-butylthiophene. 

Reaction XX. (6) Action of certain Anhydrous Metallic Halides (Aluminium Chloride, Aluminium Bromide, Aluminium and Hydrogen Chloride, Ferric Chloride) on a mixture of an Aromatic Hydrocarbon or certain Derivatives, and an Acyl Halide. (Friedel-Crafts.) (A. Ch., [6], 1, 518.)—This is an even more important application of the Friedel-Crafts synthesis than the methods of synthesising hydrocarbons (pp. 58, 60). The reactions involved are more readily controlled since the products, in presence of aluminium chloride, do not undergo further condensations. Usually these products have also the advantage of being more easily separated, for, as shown below in (iii.), the formation of isomers can be avoided. 

At the time the chemistry of (OC)9Co3CCO+PF6 was being developed (27, SO), another route to this novel acylium ion was found in these laboratories (31, 32). This discovery was a result of our intention to adapt the Friedel-Crafts synthesis of benzylidynetricobalt nonacarbonyl complexes of Dolby and Robinson (15) to the preparation of alkyl derivatives of methylidynetricobalt nonacarbonyl, whose general preparation was not well in hand. The reaction chosen for investigation was the aluminum chloride-induced interaction of tetraalkyltin compounds with ClCCo3(CO)9 In analogy to a known ketone synthesis (33),... 

The Friedel-Crafts synthesis involves the union of a relatively active compound, like a halide, with a relatively stable hydrocarbon in the presence of an anhydrous halide of aluminum, iron or zinc. For example, when a mixture of benzyl chloride and benzene are treated in the cold with aluminum chloride, a vigorous reaction takes place with elimination of hydrogen chloride resulting in the union of the phenyl and benzyl radicals to form diphenylmethane ... 

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