Acetophenone, acidity condensation

Oarboxy-arsinie Adds and their Derivatives—Nitro-, Amino- and Hydroxy-carboxyarylarsinic Acids—Condensation Products of Dichloro-p-arsino-benzoyl (boride with Amino-adds and Bligher Alcohols —. senatod Benza ide and its Derivatives, Arsenated Benzophenone and its Derivatives—Arsenated Acetophenone Derivatives. 

As will be discussed in the next section, 1,5-pentanediones are obtained by Michael addition of acetophenones to chalcones. The addition and cyclization may be merged in one step (see Section II,C,2,g). When acetophenone was condensed with chalcone (74) in the presence of BFg-EtaO or of HC104, jS-phenylpropio-phenone (76) was obtained as by-product its formation is due to hydride transfer to the conjugate acid of chalcone (75), which is the acceptor (experimental data and theoretical calculations show that chalcones are protonated at the oxygen atom). Balaban obtained a 72% yield in the conversion 70 -> 37 using as acceptor chalcone and as catalysts perchloric or sulfuric acids (i.e., 75). The formation of j8-phenylpropiophenone (76) in the Chichibabin synthesis of pyridines from chalcones and ketones in the presence of ammonium acetate, and in the pyrimidine synthesis from chalcones and amidines is undoubtedly due to a similar hydride transfer. 

Synthesis and Properties. Polyquinolines are formed by the step-growth polymerization of o-aminophenyl (aryl) ketone monomers and ketone monomers with alpha hydrogens (mosdy acetophenone derivatives). Both AA—BB and AB-type polyquinolines are known as well as a number of copolymers. Polyquinolines have often been prepared by the Friedlander reaction (88), which involves either an acid- or a base-catalyzed condensation of an (9-amino aromatic aldehyde or ketone with a ketomethylene compound, producing quinoline. Surveys of monomers and their syntheses and properties have beenpubhshed (89—91). 

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). 

Chapters 1 and 2. Most C—H bonds are very weakly acidic and have no tendency to ionize spontaneously to form carbanions. Reactions that involve carbanion intermediates are therefore usually carried out in the presence of a base which can generate the reactive carbanion intermediate. Base-catalyzed condensation reactions of carbonyl compounds provide many examples of this type of reaction. The reaction between acetophenone and benzaldehyde, which was considered in Section 4.2, for example, requires a basic catalyst to proceed, and the kinetics of the reaction show that the rate is proportional to the catalyst concentration. This is because the neutral acetophenone molecule is not nucleophihc and does not react with benzaldehyde. The much more nucleophilic enolate (carbanion) formed by deprotonation is the reactive nucleophile. 

Krivun, Shian, and Dorofeenko condensed acetylacetone or dibenzoylmethane with various ketones (acetone, acetophenone, acetothienone, 1-acetylnaphthalene, or 5-acetylacetaphthene) and obtained pyrylium salts in 10-20% yield in the presence of perchloric acid. 

On the other hand, 1,1,1-trisubstituted alkanes behave similarly to aldehydes, yielding pyrjdium salts (128) with identical substituents in positions 2 and 6. Thus, Dorofeenko and co-workers condensed 2 moles of acetophenone with 1 mole of benzotrichloride in the presence of perchloric acid obtaining 2,4,6-triphenjdpjTylium perchlorate with 1 mole of ethyl orthoformate, they obtained 2,6-diphenyl-pyrylium perchlorate (57) from o-hydroxyacetophenone, ortho-formic ester and perchloric acid, 4-ethoxybenzopyrylium perchlorate was formed. 

The course of the reaction may involve either the acylation of the ketone to a -diketonic intermediate following thereupon the pathway in Section II, C, 2, a, or alternatively the condensation of two moles of ketone to yield an intermediate dypnone which then undergoes acylation following the pathway in Section II,C, l,a. Dilthey and Fischer thought the first alternative more plausible, on the basis of reaction yields, and this lead them to explore the pathway in Section II,C,2,a. Schneider and Ross and Diels and Alder believed that the second alternative operates. Both views are plausible since acylations of methyl ketones to S-diketones are known to take place in the conditions of this reaction, and dypnone ha.s been isolated from acetophenone on treatment with Friedel-Crafts catalysts, in the absence of an acid anhydride or chloride (an excess of catalyst... 

Ethyl benzoylacetate has been prepared by the condensation (by means of sodium ethylate) of ethyl acetate with ethyl benzoate,1 acetophenone with ethyl carbonate,2 and acetophenone with ethyl oxalate, with subsequent heating 3 by treatment of ethyl phenylpropiolate4 or a-bromocinnamic acid 5 with concentrated sulfuric acid, and of ethyl diazoacetate with benzalde-hyde 6 by the condensation of benzene with the monoethyl ester of malonyl monoacid chloride and aluminum chloride,7 of benzoyl chloride with the product of the reaction of magnesium and ethyl chloroacetate in ether,8 of alcohol on benzoylacetimino ethyl... 

Aryl substituted quinohnes 216 have also been prepared through a microwave-assisted Friedlander condensation between various acetophenones 215 and 2-aminoacetophenones 214 in the presence of a catalytic amount of diphenylphosphate (Scheme 78). These conditions are less acidic than the others reviewed here for the synthesis of quinohnes [138]. 

Sadvilkar et al. (1995) have studied condensation of benzaldehydes with acetophenones (Claisen-Schmidt reaction) in an aqueous medium, containing sodium butylmonoglycol sulphate and sodium salts of aromaticsulphonic acids as hydrotropes. A substantial improvement in the rate of reaction was realized, while product recovery was facilitated. 

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