Ketones, aliphatic reactions

The enamines of cyclic ketones, on reaction with aliphatic and aromatic aldehydes, give good yields of the 2-monoalkylidene derivative of the corresponding ketones (J28). The first step in the reaction appears to be the... 

An antipolymerization agent such as hydroquinone may be added to the reaction mixture to inhibit the polymerization of the maleate or fumarate compound under the reaction conditions. This reaction is preferably carried out at a temperature within the range of 20°C to 150°C. This reaction is preferably carried out at atmospheric pressure. Reaction time of 16 to 24 hours have bean specified for this reaction by J.T. Cassaday. The reaction is preferably carried out in a solvent such as the low molecular weight aliphatic monohydric alcohols, ketones, aliphatic esters, aromatic hydrocarbons or trialkyl phosphates. 

The preceding discussion applied to aromatic ketone triplet reactions. With aliphatic ketones the situation is quite dilferent. As stated previously, aliphatic ketones undergo type II cleavage from both the excited singlet and the triplet state. By studying the reaction with and without added quencher, one can determine the characteristics of the reaction for each state, that is, the singlet reaction can be studied in the presence of a strong triplet quencher while the triplet reaction characteristics can be obtained by the difference between the reaction without quencher and that when quencher is added. For example, for the reaction... 

Variations on this theme include the use of acrolein/ammonia (72GEP2224160) and acrolein/acetaldehyde/ammonia (64BRP963887,69BRP1141526). Ketones can also be utilized. For example, 2,6-dimethylpyridine is obtained in 36% yield from combination of for-malin/acetone/ammonia (71GEP2064397) (Scheme 3). This general reaction has recently been extended to include the preparation of 2,6-disubstituted (78BEP858390) and 2,3-disubstituted (78GEP2712694) pyridines from aromatic or heteroaromatic ketones/aliphatic aldehydes and ammonia. 

In 1953, Percival and coworkers showed that aliphatic ketones can be prepared under these conditions. Unfortunately, in the case of linear aliphatic ketones the reaction only gives moderate yields, since the Grignard reagent adds to the ketone or behaves as a base... 

Dekalogenation of a-haio ketones. This reaction can be effected with Nal in T1II- 11,0 (1 1) containing 5% H, S04 at 25". In the case of aliphatic a-halo ketones... 

Hence, the first clearcut evidence for the involvement of enol radical cations in ketone oxidation reactions was provided by Henry [109] and Littler [110,112]. From kinetic results and product studies it was concluded that in the oxidation of cyclohexanone using the outer-sphere one-electron oxidants, tris-substituted 2,2 -bipyridyl or 1,10-phenanthroline complexes of iron(III) and ruthenium(III) or sodium hexachloroiridate(IV) (IrCI), the cyclohexenol radical cation (65" ) is formed, which rapidly deprotonates to the a-carbonyl radical 66. An upper limit for the deuterium isotope effect in the oxidation step (k /kjy < 2) suggests that electron transfer from the enol to the metal complex occurs prior to the loss of the proton [109]. In the reaction with the ruthenium(III) salt, four main products were formed 2-hydroxycyclohexanone (67), cyclohexenone, cyclopen tanecarboxylic acid and 1,2-cyclohexanedione, whereas oxidation with IrCl afforded 2-chlorocyclohexanone in almost quantitative yield. Similarly, enol radical cations can be invoked in the oxidation reactions of aliphatic ketones with the substitution inert dodecatungstocobaltate(III), CoW,20 o complex [169]. Unfortunately, these results have never been linked to the general concept of inversion of stability order of enol/ketone systems (Sect. 2) and thus have never received wide attention. 

Esters have been prepared in 63-73% yields from several simple cycloalkyl and aryl alkyl ketones by reaction at room temperature with per-benzoic acid. The larger radical of the ketone appears as the alcohol fragment of the ester. Cyclic ketones are oxidized by potassium persulfate and sulfuric acid to esters from which o>-hydroxy aliphatic esters are obtained upon hydrolysis and reesterification. Peracetic acid in acetic anhydride converts salicylaldehyde to o-hydroxyphenyl formate (88%). ... 

Many water-insoluble ketones, aliphatic, aryl aliphatic, and heterocyclic, respond favorably to treatment with ammonium formate or formamide to form with subsequent hydrolysis the primary amines. A typical procedure for the synthesis of a-phenylethylamine (66%) from acetophenone and ammonium formate has been applied to many other ketones (65-84%). Nuclear alkoxyl, halo, and nitro groups are not disturbed. The reaction with formamide as the reducing agent is catalyzed by ammonium formate, ammonium sulfate, or magnesium chloride. ... 

Ketones Aliphatic ketones formed by autoxidation of lipids also contribute to the flavor of oils and food products. For example, Guth and Grosch (13) identified l-octen-3-one as one of the odor-active compounds in reverted soybean oil. This compound was described as metallic and mushroom-like. The reaction pathway for the formation of l-octen-3-one from the linoleate-10-hydroperoxide via the p-scission route is illustrated in Figure 2. 10-Hydroperoxide of linoleate is not the usual hydroperoxide formed by autoxidation of linoleate however, it is one of the major hydroperoxides formed by the photosensitized oxidation (singlet oxygen reaction) of linoleate (14). 

Because of the difficulties of purification and handling, many of the results for diazoalkanes have been obtained from reactions in which the diazo compound is not the starting material but in which it may reasonably be supposed to be an intermediate. Most popular in this respect has been the base-catalysed decomposition of arylsulphonyl-hydrazones of aliphatic aldehydes and ketones, a reaction which was first investigated by Bamford and Stevens (1952). Because the reaction... 

The Claisen-Schmidt Reaction. When aromatic aldehydes are treated with aliphatic ketones in the presence of base, three reactions might be expected a Cannizzaro reaction of the aromatic aldehyde an aldol-type reaction of the ketone or a crossed aldol reaction between the ketone and the aromatic aldehyde. In either of the last two possibilities dehydration might also occur. Undoubtedly all these reactions will take place in strong base, but by employing about 10 per cent aqueous sodium hydroxide, good yields are often obtained of j3-unsaturated carbonyl conipounds derived from a crossed aldol reaction between the aldehyde and the ketone. This reaction, generally called a Claisen-Schmidt reaction, can be illustrated by the synthesis of benzalacetophenone.16... 

Dubois and Fellmann have studied the kinetic regioselectivity in the base-promoted reactions of 2-bu-tanone and 2-pentanone with a series of aliphatic aldehydes (equation 52) results are summarized in Table 2. The data indicate that steric effects play a subtle role in the determination of aldol regiochem-istry in unsymmetrical ketones. Although reaction at C-3 is favored for 2-butanone with all of the aldehydes, pivalaldehyde gives more reaction at C-1 than the other aldehydes studied. Selectivity for reaction at C-3 in 2-pentanone is significantly less with all aldehydes, especially pivalaldehyde. 

Heterocycles. Lewis acid-catalyzed reaction with aromatic aldehydes followed by CAN oxidation in methanol leads to methyl 2-aryltetrahydrofuran-4-carboxylates. The reactivity of aliphatic aldehydes and ketones is inferior, and for ketones the reaction proceeds better using TiCU as catalyst. 

Methyl ketones. Nitriles (aliphatic and aromatic) are converted into methyl ketones by reaction with trimethylaluminum in the presence of various catalysts,... 

Schiff s reagent An aqueous solution of magenta dye decolorized by reduction with sulfur(IV) oxide. It is a test for aldehydes and ketones. Aliphatic aldehydes restore the color quickly aliphatic ketones and aromatic aldehydes slowly aromatic ketones give no reaction. 

The solvent-free one step Beckmann rearrangement of ketones 1 and aldehydes in the presence of zinc oxide afforded the corresponding amides 3 (R = alkyl, aryl, cycloalkyl = H, cycloalky 1). Symmetrical ketones furnished the amides in good to excellent yields. In the case of unsymmetrical ketones the reaction was selective and one of the two possible amides was formed. Aromatic and aliphatic aldehydes were converted to the corresponding primary amides. 

Surface modifications of polymers is brought about by the introduction of alcohol functionality, e.g., poly(tetrafluoroethylene-co-hexafluoropropylene) on reduction with sodium naphthalide in THF results in an unsaturated modified surface layer, the thickness of which is controlled with reaction time and temperature. The air sensitive surface contains alcohols, ketones, aliphatic C-H bonds in addition to C=C and C C. The more alcoholic groups are introduced by hydroboration-oxidation, but the esterification leads to the formation of ester in lower yield. This reveals that the reactivity of OH group is similar to hindered alcohols. The reactivity of the surface can be enhanced by chain extension of secondary surface alcohols with ethylene oxide to form a surface containing primary alcohols groups separated from the polymer backbone by C-2 spacer. On the other hand, primary alcohols are directly introduced to the surface by reaction of the reduced layer with 9-BBN, followed by carbonylation and reduction [5]. 

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