Friedel-Crafts reaction, aromatic hydrocarbons ketones

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... 

Friedel-Crafts reaction org chem A substitution reaction, catalyzed by aluminum chloride in which an alkyl (R —) or an acyl (RCO —) group replaces a hydrogen atom of an aromatic nucleus to produce hydrocarbon or a ketone. fre del krafs re.ak shan ... 

The conventional method for preparation of these aromatic ketones involves reaction of the aromatic hydrocarbon with a carboxylic acid derivatives using a Lewis acid (AICI3, FeCb, BF3, ZnCb, TiCl4) or Bronsted acids (polyphosphoric acid, HF). The major drawback of the Friedel-Crafts reaction is the need to use a stoicheiometrical quantity of Lewis acid relative to the formed ketone. This quantity is required due to the fact that the... 

Acid chlorides are used extensively as electrophiles in the Friedel-Crafts reaction to prepare aromatic ketones. The reaction involves the treatment of an aromatic hydrocarbon with an acyl chloride in the presence of a Lewis acid, such as aluminum chloride (see Experiment [27]). Using this reaction, outline the reaction sequence you would use to prepare... 

In another approach, poly(aryl ether sulfones) were synthesized by the electrophilic Friedel-Crafts reactions of sulfonyl halides with aromatic hydrocarbons. The critical step in these polymerizations is the formation of the carbon-sulfur bond. High polymers were obtained, though they were not always completely linear. Carbonyl aryl carbon-carbon bonds are created in Friedel Craft reactions leading to poly(aryl ketones). 

By the Friedel and Crafts reaction. The condensation of an acid chloride or an acid anhydride with an aromatic hydrocarbon in the presence of anhydrous aluminium chloride generally gives a good yield of the aromatic ketone ... 

Ketones containing a double bond have also been prepared by the reaction of unsaturated acyl halides with aromatic hydrocarbons in the usual Friedel-Crafts manner. Acylation of benzene and its homologs with /S,/S-dimethylacroyl chloride leads to dimethylvinyl aryl ketones, (CHj)jC = CHCOAr (75-90%). °° The latter compounds are stable and do not undergo intramolecular condensation. 

Gore, P. H. The Friedel-Crafts acylation reaction and its application to polycyclic aromatic hydrocarbons. Chem. Rev. 1955, 55, 229-281. Eyiey, S. C., Rainey, D. K. Aldehydes and ketones. General and Synthetic Methods 1981,4, 26-86. 

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). 

One of the major problems encountered in this synthesis is the difficulty of obtaining the starting materials (either the a-aminocarbonyl compounds or their acylated derivatives). The former may be prepared by Neber rearrangement of ketoxime tosylates with a base such as ethoxide or pyridine.46 a-Acylamino carbonyl compounds can be prepared directly by the reductive acetylation of oximino ketones.28 38 Balaban and his collaborators47-60 have developed an excellent method for the synthesis of a-acylamino ketones (5). They are obtained in yields of 50-90% by the reaction of azlactones (2-aryl-5-oxazolone, 4) with aromatic hydrocarbons in the presence of aluminum chloride under Friedel-Crafts conditions the reaction may proceed either intermolecularly or intramolecularly. 

The aromatic ketones are most conveniently prepared by means of the Friedel and Crafts reaction from acyl chlorides and aromatic hydrocarbons —... 

Friedel and Crafts also discovered that treating an aromatic hydrocarbon with an acyl halide in the presence of aluminum chloride gives a ketone. An acyl halide is a derivative of a carboxylic acid in which the —OH of the carboxyl group is replaced by a halogen, most commonly chlorine. Acyl halides are also referred to as acid halides. An RCO— group is known as an acyl group hence, the reaction of an acyl halide with an aromatic hydrocarbon is known as Friedel-Crafts acylation, eis illustrated by the reaction of benzene and acetyl chloride in the presence of aluminum chloride to give acetophenone ... 

An important reaction which enabled many new aromatic compounds to be prepared was that discovered in 1877 by Charles Friedel (1832-1899) and James Mason Crafts (1839-1917). They found that an alkyl or acyl group could be substituted into a benzene ring by the reaction of the aromatic hydrocarbon with an alkyl or acyl halide in the presence of aluminium chloride catalyst. The reaction proved to be of wide application and is particularly useful in the preparation of aromatic ketones and in the formation of a new ring by an intramolecular process (Figure 10.11). 

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