Friedel-Crafts condensation

As is the case during manufacture, contact with those metallic impurities that catalyze Friedel-Crafts condensation reactions must be avoided. The self-condensation reaction is exothermic and the reaction can accelerate producing a rapid buildup of hydrogen chloride pressure in closed systems. 

In principle, polymers equivalent to those obtained from vinyl and divinyl monomers may be synthesized by this method. The product in the above example possesses the same chain structure as polyethylene. The polymerization process, notwithstanding the likelihood of a metal alkyl intermediate, should conform satisfactorily to stepwise condensation. However, the product, and those obtained by Friedel-Crafts condensation as well, lack the recurrent functional groups which generally characterize condensation polymers. 

Examples of branched polymers of the type under consideration are few. Polymers prepared by Friedel-Crafts condensation of benzyl halides doubtless are properly described as such... 

Styrene is produced by the catalytic vapor phase dehydrogenation of ethylbenzene. Ethylbenzene is made by the Friedel-Crafts condensation of ethylene and benzene. Styrene is also produced by the palladium acetate-catalyzed condensation of ethylene and benzene and by the dehydration of methylphenylcarbinol obtained by the propylation of ethylbenzene. Because of the toxicity of styrene, its concentration in the atmosphere must be severely limited. 

Friedel-Crafts condensation Condensation that takes place in the presence of a Lewis acid such as aluminum chloride. 

Both types of wax are readily oxidized (24) and halogenated (116). The latter is an important commercial outlet, the products of which are used as extreme pressure additives for oil (112,113) and as intermediates in Friedel-Crafts condensations (119). Air oxidation leads to carboxylic acids, for which considerable use has been found both here and abroad. Sulfonates can be made by reaction of waxes with chlorosulfonic acid (37,104) or with sulfur dioxide and chlorine (46,99). 

Concerning electrophilic side reactions, intramolecular Friedel-Crafts condensations have been reported for example, fluorenone is formed from 2-benzoylbenzenediazonium tetrafluorobo-rate.241 The strong Lewis acid boron trifluoride can also be responsible for side reactions, such as the extensive formation of tars from nitro-substituted arenediazonium tetrafluorobor-ates or the acidic hydrolysis of ester substituents, especially in the case of 2-(ethoxycar-bonyl)benzenediazonium tetrafluoroborate.105,242... 

Ring synthesis by y- closure is a somewhat more versatile entry into this class of compound, though even then it is restricted to suitably activated precursors such as (142) (equation 101) (72T5197). Thiochromones and thioxanthones are probably most frequently prepared by this mode of closure, usually via an intramolecular Friedel-Crafts condensation of a carboxylic acid with an aromatic ring (equation 102) (71GEP2006196). 

In this respect, the aromatic component of such Friedel-Crafts condensation may be considered to function as a nucleophilo, in which w-electrona attack the aluminum chloride-coordinated ethylene oxide ring. 

Friedel-Crafts condensation with sulphonyl chlorides.508... 

Very recently it has been reported that the Friedel-Crafts condensation of aromatic disulfonyl chlorides with aromatic ethers has been successfully effected to yield high molecular weight polymers (20)... 

J. C. S., 117,1330.)—This modification of the Friedel-Crafts condensation has been fully dealt with under its application to the synthesis of hydrocarbons. In the case of ketones the results obtained are more in accordance with the results of the older method than were those discussed in the first hydrocarbon section. 

Methylcyclohexanecarboxylic acid can be prepared by car-bonation of the Grignard reagent from 1-chloro-l-methylcyclo-hexane3 or by Friedel-Crafts condensation of 1-chloro-l-methyl-cyclohexane with methyl 2-furancarboxylate followed by saponi-... 

Cyclodehydration. Neat, anhydrous CH3S020H is at least as useful as polyphosphoric acid for cyclization of 3-arylpropanoic acids and 4-arylbutanoic acids to indanones and tetralones.1 However, it does not appear to be useful for intermolecular Friedel-Crafts condensation. Examples ... 

There are different methods of the synthetic preparation of acronycine (W. M. Bandaranayake et al., J. Chem. Soc. Perkin 1, 998 (1968) J. Hlubucek et al. Aust. J. Chem. 23, 1881 (1970). One of them is described below. Friedel-Crafts condensation between 2-nitrobenzoyl chloride and 3,5-dimethoxyphenol. 

Several chemicals are manufactured by application of the Friedel-Crafts condensation reaction. Efficient operation of any such process depends on ... 

A very nice example of the use of thioxophospholes as protected phospholes is given by Matano et a/., as part of the synthesis of phosphole-containing calixphyrins <20060M3105, 2006JA11760>. The key to the success of this approach lies in the use of Friedel-Crafts condensations involving phospholes 88 and 89 (Scheme 25). These... 

Similarly, 2-chloroacetylphenoxazine, 2-propionylphenoxazine, and 2-butyrylphenoxazine have been obtained by Friedel-Crafts condensation of phenoxazine with the proper acyl halides.58-60... 

The Friedel-Crafts condensation is also useful for the synthesis of deoxynucleosides, e.g. 3 -azido-3 -deoxyadenosine. Recently, (3,(V-bis(trimethylsilyl)acetamide, instead of hexa-methyldisilazane (HMDS), has been used for the silylation. A, 7V-Bis(trimethylsilyl)acetamide does not introduce chemically interactive side products and has been found to be superior as a silylating agent, especially for one-pot reactions. ... 

Clemmensen reaction. The Clemmensen method of reduction (1913) consists in refluxing a ketone with amalgamated zinc and hydrochloric acid. Acetophenone, for example, is reduced to ethylbenzene. The method is applicable to the reduction of most aromatic-aliphatic ketones to at least some aliphatic and alicyclic ketones, to the y-keto acids obtainable by Friedel-Crafts condensations with succinic anhydride (succinolylation), and to the cyclic ketones formed by intramolecular condensation. 

There are several types of polyaryl sulfones available commercially. The classic polysulfone (Udal) was produced by the nucleophilic displacement of the chlorine substituents on bis(p-chlorophenyl) sulfone by the sodium salt of blsphenol A.Another polysulfone (Astrel) is produced by the Friedel-Crafts condensation of biphenyl with oxy-bis(benzene sulfonyl chloride). Another polysulfone (Vitrex), is produced by the alkaline condensation of bis(chlorophenyl) sulfone. (28.)Blends of polysulfones with ABS (Arylon, Mlndel) and SAN (Ucardel) are available. 

Sulfonium Salts Triaryl sulfonium salts (TPSs) are generally produced by the method of Pitt [23]—a Friedel-Crafts condensation of aromatic hydrocarbons with... 

Furthermore, the decomposition of the zinc enolate to allylic halide is favored by substitution in the allyl portion. The halide then undergoes Friedel Crafts condensation with the aromatic solvent catalyzed by zinc bromide present in the reaction. 

Condensation of trichloromethyl perchloroaromatic compounds with trichloroethylene 319 Friedel-Crafts condensation 320 Twisted ethylenes 321 Atropisomerism 322... 

Nevertheless, because of compelling needs closely related to the synthesis of some substituted inert free radicals (Section 9), that Friedel-Crafts condensation has recently been explored, using as alkylating components a//-chlorocompounds (such as a//-heptachlorotoluene, and a//-undeca-chlorodiphenylmethane) and even chloroform. With aromatic substrates, such as 1,3,5-trichlorobenzene, 1,2,4,5-tetrachlorobenzene and pentachloro-benzene, good-to-excellent yields of the expected a//-arylmethanes are obtained. Examples are shown in (74). Such condensations take place in... 

Friedel-Crafts condensation of benzo[Z ]thieno[3,2-Z ]thiophene-2-carboxylic acid chloride with m- and / -xylene affords ketones, which undergo Elbs pyrolysis (420 °C, 15 min) to form pentacyclic derivative 230 (2000JA1082). Analogous products were prepared from benzo[Z ]thieno[3,2-Z ]thiophene and (di)methyl homologues of benzoyl chloride. 

This is a typical electrophilic aronatic substitution in which the aromatic substrate is attacked by some form of the arylsulphonylium cation and hydrogen displaced as a proton. The attacking reagent is formed by interaction of the sulphonyl chloride with a Friedel Crafts catalyst the catalyst should be selected from Fed, SbCl or Ind, since with these halides only catalytic quantities are requiredf in contrast to the equimolar quantities usually recommended for Friedel Crafts condensations %d.th acid halides (9). This choice of catalyst is important as it eliminates side reactions and helps considerably with the problem of catalyst removal from the polymers. 

Reactions of Hydrocarbons. Several types of reactive hydrocarbon functional groups can be used to polymerize and cross-Unk monomers and ohgomers into thermoset plastics. These include addition polymerization of acetylene-terminated molecules and ring-opening polymerization of strained carbon rings. They also include Friedel-Crafts condensation to form hydrocarbon polymers. 

Since the initial work of Chardonnens and others, few examples of syntheses of [l,2-a]IF derivatives exist outside of patent literature. Shi et al. recently reported [l,2-a]IFs 48a,b and [2,l-c]IFs 49a,b (Scheme 10) [46]. Diels-Alder reaction of alkynes 45a,b, readily available from fluorenones 44a,b, provided regioisomeric mixtures of diols 46a,b and 47a,b. Subsequent acid-catalyzed Friedel-Crafts condensation gives 48 and 49. The two derivatives of both regioisomers showed quantum yields in solution of 60% and showed good thermal stability, with decomposition occurring at temperatures greater than 330 °C. 

The Friedel-Crafts condensation of ethylene oxide with aromatics gives aryl ethanols in good yields. 

The Friedel-Crafts condensation reaction of aromatic hydrocarbons with sulfonyl chlorides yields sulfones. 

Favorskii rearrangement, 25 Friedel-Crafts acylation, 56-57 Friedel-Crafts alkylation, 5, 11-12 Friedel-Crafts condensation, 29-30... 

In addition to nucleophilic aromatic substitution, there are a number of other synthetic routes to poly(aryl ethers). Friedel-Crafts condensation of arylsulfonyl chlorides and aryl carboxylic acid derivatives with aryl ethers has been employed to prepare polysulfones (2b) and poly(ether ketones) (105,106), respectively. Direct polycondensation of various benzoic acids containing a phenyl ether structure has been carried in 1 10 phosphorous pentoxide/methanesulfonic acid (107). The success of this method is a consequence of the high selectivity of the electrophilic reagent for substitution para to the ether linkage. 

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