Ketone, aromatic

Aromatic ketones are solid at room temperature. They are used as starting compounds for 

They have no action on aluminium that can be used for the fabrication and transportation of these products. 

Anthraquinone is used in a production process for hydrogen peroxide in which a very large number of pieces of equipment such as reaction vessels and heat exchangers are in aluminium (see Section E.1.9). 

Sulphonic acids of anthraquinone, when produced in presence of mercury, may lead to a slight attack of aluminium. 

Several of them belong to the fifty most important chemicals produced in the United States, according to a ranking established in 1990 terephthalic acid (rank 23), acetic acid (rank 34), adipic acid (rank 46), and isopropyl acid (rank 48). 

TABLE 5.6 Hydrogenation of Aryl Ketones to Alcohols over Copper-Chromium Oxide0-  

Aromatic Ketone Temperature (°C) Time (h) Aromatic Alcohol Hydrocarbon 

In a patent, lead-poisoned palladium catalyst was claimed to be effective for hydrogenation of benzophenone to benzhydrol at 115°C and 0.34 MPa H2.115 Kumbhar and Rajadhyaksha hydrogenated benzophenone to benzhydrol in 98.4% selectivity at 88% conversion over Ni-Fe (75 25) on Ti02 using methanol-10% water as solvent and NaOH (0.1 wt% of benzophenone) as additive at 135°C and 5.9 MPa H2.116 

Over Ni-kieselguhr (eq. 5.35, A),121 copper-chromium oxide (eq. 5.35, B)7 and Raney Ni (eq. 5.35, C)122 in ethanol, ethyl acetoacetate is hydrogenated quantitatively to ethyl 3-hydroxybutyrate under the conditions described in eq. 5.35. 

Similar to p-keto esters, P-keto amides may be readily hydrogenolyzed by conditions. Thus, 3-acyloxyindole (10), a P-keto amide, is cleanly hydrogenolyzed to the corresponding 3-alkyl derivative in ethanol over Adams palladium oxide catalyst (eq. 5.37).126 

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  

It should be noted that the Friedel-Crafts acylation differs from the Friedel-Crafts alkylation (compare Sections IV,3-4 and discussion preceding Section IV,1) in one important respect. The alkylation requires catal3d.ic quantities of aluminium chloride, but for acylation a molecular equivalent of aluminium chloride is necessary for each carbonyl group present in the acylating agent. This is because aluminium chloride is capable of forming rather stable complexes with the carbonyl group these complexes probably possess an oxonium 

The use of aliphatic acid anhydrides in place of acid chlorides offers many advantages these include  

The examples of the Friedel and Crafts reaction described include the following — 

A further example is given below illustrating the use of a dibasic anhydride (succinic anhydride) the succinoylation reaction is a valuable one since it leads to aroyl carboxylic acids and ultimately to polynuclear hydrocarbons. This general scheme of synthesis of substituted hydrocarbons through the use of succinic anhydride is sometimes called the Haworth reaction. Thus a-tetralone (see below) may be reduced by the Clemmensen method to tetralin (tetrahydronaphthalene) and the latter converted into naphthalene either catal3d.ically or by means of sulphur or selenium (compare Section, VI,33). 

Aromatic alcohols are obtained by the hydrolysis of benzyl halides and by the reduction of aromatic aldehydes and ketones. 

Both formyl and acyl groups can be introduced directly into an aromatic ring under Friedel-Crafts conditions to form aromatic aldehydes and ketones, 

Both aromatic aldehydes and ketones undergo normal carbonyl group reactions with nucleophilic reagents. 

Aromatic aldehydes have no a-hydrogen atom and so cannot form carbanions. 

Carbanions can be generated from a variety of substrates by the base-catalysed abstraction of an a-hydrogen atom. 

When the alkyl chain is C3 or longer, cleavage of the C—C bond once removed from the C=0 group occurs with hydrogen migration. This is the same cleavage noted for aliphatic ketones that proceeds through a cyclic transition state and results in elimination of an alkene and formation of a stable ion. 

Since the intensity of the m/z 141 peaks is about the intensity of the m/z 139 peak, these peaks correspond to fragments containing 1 chlorine each. The same can be said about the fragments producing the m/ z 111 and 113 peaks. 

Aromatic aldehydes and ketones react with carbanions to yield aryl-substituted alkene derivatives. 

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SchifT s reagent A solution of rosaniline in water decolorized with sulphurous acid. Aliphatic aldehydes and aldose sugars give a magenta colour with this reagent with aromatic aldehydes and aliphatic ketones the colour develops more slowly aromatic ketones do not react. 

Aromatic ketones undergo this type of reduction particularly readily. 

The ketones are readily prepared, for example, acetophenone from benzene, acetyl chloride (or acetic anhydride) and aluminium chloride by the Friedel and Crafts reaction ethyl benzyl ketones by passing a mixture of phenylacetic acid and propionic acid over thoria at 450° and n-propyl- p-phenylethylketone by circulating a mixture of hydrocinnamic acid and n-butyric acid over thoria (for further details, see under Aromatic Ketones, Sections IV,136, IV,137 and IV,141). 

Unsaturated hydrocarbons are present in nearly all products of the Clemmensen reduction of aromatic ketones and must be removed, if the hydrocarbon is requiral pure, by the above process. Secondary alcohols, often produced m small amount are not appreciably steam-volatile. 

Aromatic ketones usually have relatively high boiling points, but distil with little or no decomposition. Many are solids. The vapours generally burn with a smoky flame. They react with the 2 4-dinitrophenyll hydrazine reagent (Section 111,74,/) or with the phenylhydrazine reagent... 

The melting points of various derivatives of a number of typical aromatic ketones are collected in Table IV.148. 

Seeing the aromatic ketones in a and c we might have a Friedel-Crafts reaction in mind. Continue tiiese two a stage further. 

Lithiated indoles can be alkylated with primary or allylic halides and they react with aldehydes and ketones by addition to give hydroxyalkyl derivatives. Table 10.1 gives some examples of such reactions. Entry 13 is an example of a reaction with ethylene oxide which introduces a 2-(2-hydroxyethyl) substituent. Entries 14 and 15 illustrate cases of addition to aromatic ketones in which dehydration occurs during the course of the reaction. It is likely that this process occurs through intramolecular transfer of the phenylsulfonyl group. 

Reaction of the aromatic (eg, C H ), acyl haUde (RCOX), and aluminum haUde (AIX ) Hberates hydrogen haUde and produces a complex of aromatic ketone and aluminum haUde from which the ketone is Hberated by hydrolysis ... 

In contrast, aromatic ketones are high boiling, colorless Hquids that generally have a fragrant odor and are almost insoluble in water. They are useful as intermediates in chemical manufacture. Functionalized and cycHc ketones are also good solvents. Ring size and the type and location of functional groups affect odor, color, and reactivity of these ketones. 

Aromatic ketones of industrial significance include acetophenone, propiophenone, and benzophenone. 

Contaminants and by-products which are usually present in 2- and 4-aminophenol made by catalytic reduction can be reduced or even removed completely by a variety of procedures. These include treatment with 2-propanol (74), with aUphatic, cycloaUphatic, or aromatic ketones (75), with aromatic amines (76), with toluene or low mass alkyl acetates (77), or with phosphoric acid, hydroxyacetic acid, hydroxypropionic acid, or citric acid (78). In addition, purity may be enhanced by extraction with methylene chloride, chloroform (79), or nitrobenzene (80). 

Friedel-Crafts Acylation. The Friedel-Crafts acylation procedure is the most important method for preparing aromatic ketones and thein derivatives. Acetyl chloride (acetic anhydride) reacts with benzene ia the presence of aluminum chloride or acid catalysts to produce acetophenone [98-86-2], CgHgO (1-phenylethanone). Benzene can also be condensed with dicarboxyHc acid anhydrides to yield benzoyl derivatives of carboxyHc acids. These benzoyl derivatives are often used for constmcting polycycHc molecules (Haworth reaction). For example, benzene reacts with succinic anhydride ia the presence of aluminum chloride to produce P-benzoylpropionic acid [2051-95-8] which is converted iato a-tetralone [529-34-0] (30). 

Hydroxyl Group. The OH group of cyanohydrins is subject to displacement with other electronegative groups. Cyanohydrins react with ammonia to yield amino nitriles. This is a step in the Strecker synthesis of amino acids. A one-step synthesis of a-amino acids involves treatment of cyanohydrins with ammonia and ammonium carbonate under pressure. Thus acetone cyanohydrin, when heated at 160°C with ammonia and ammonium carbonate for 6 h, gives a-aminoisobutyric acid [62-57-7] in 86% yield (7). Primary and secondary amines can also be used to displace the hydroxyl group to obtain A/-substituted and Ai,A/-disubstituted a-amino nitriles. The Strecker synthesis can also be appHed to aromatic ketones. Similarly, hydrazine reacts with two molecules of cyanohydrin to give the disubstituted hydrazine. 

ROBINSON - ALLAN - KOSTANECKI Chromone Synthesis Synthesis of chromones or coumannes from o acyioxy aromatic ketones... 

The rates of the reactions of several aromatic ketones with alkyllithium reagents have been examined. The reaction of 2,4-dimethyl-4 -(methylthio)benzophenone with methyl-lithium in ether exhibits the rate expression ... 

The intermediates which are generated are free radicals. The hydrogen-atom abstraction can be either intramolecular or intermolecular. Many aromatic ketones react by hydrogen-atom abstraction, and the stable products are diols formed by coupling of the resulting a-hydroxyben2yl radicals ... 

For some aromatic ketones the reactive dienols can also undergo electrocycliziidoa to cyclobutenols. ... 

The bicyclic product is formed by coupling of the two radical sites, while the alkene results from an intramolecular hydrogen-atom transfer. These reactions can be sensitized by aromatic ketones and quenched by typical triplet quenchers and are therefore believed to proceed via triplet excited states. 

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