Oxidative ketonization

However, all these systems suffer from high concentrations of chloride ion, so that substantial amounts of chlorinated by-products are formed. For these reasons there is a definite need for chloride- and copper-free systems for Wacker oxidations. One such system has been recently described, viz., the aerobic oxidation of terminal olefins in an aqueous biphasic system (no additional solvent) 

Moreover, it was disclosed that PdCl2 in combination with N,N-dimethylaceta-mide (DMA) solvent could offer a simple and efficient catalyst system for acid-and Cu-free Wacker oxidation [102]. The reaction is illustrated in Fig. 4.37. A wide range of terminal olefins could be oxidized to form the corresponding methyl ketones in high yields, reaching a TOF up to 17 h-1. The Pd-DMA catalyst layer could be recycled. Furthermore this system is also capable of per- 

In this context it is also worth mentioning that Showa Denko has developed a new process for the direct oxidation of ethene to acetic acid using a combination of palladium(II) and a heteropoly acid [104]. However, the reaction probably involves heteropoly acid-catalyzed hydration followed by palladium-catalyzed aerobic oxidation of ethanol to acetic acid rather than a classical Wacker mechanism. 

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Oxidation. Ketones are oxidized with powerful oxidizing agents such as chromic or nitric acid. During oxidation, carbon—carbon bond cleavage occurs to produce carboxyHc acids. Ketone oxidation with hydrogen peroxide, or prolonged exposure to air and heat, can produce peroxides. Concentrated solutions of ketone peroxides (>30%) may explode, but dilute solutions are useful in curing unsaturated polyester resin mixtures (see... 

In general, peroxomonosulfates have fewer uses in organic chemistry than peroxodisulfates. However, the triple salt is used for oxidizing ketones (qv) to dioxiranes (7) (71,72), which in turn are useful oxidants in organic chemistry. Acetone in water is oxidized by triple salt to dimethyldioxirane, which in turn oxidizes alkenes to epoxides, polycycHc aromatic hydrocarbons to oxides and diones, amines to nitro compounds, sulfides to sulfoxides, phosphines to phosphine oxides, and alkanes to alcohols or carbonyl compounds. 

Considerable interest arose during the 1970 s and 1980 s in the use of micro-organisms to produce useful fatty adds and related compounds from hydrocarbons derived from the petroleum industry. During this period, a large number of patents were granted in Europe, USA and Japan protecting processes leading to the production of alkanols, alkyl oxides, ketones, alkanoic adds, alkane dioic acids and surfactants from hydrocarbons. Many of these processes involved the use of bacteria and yeasts associated with hydrocarbon catabolism. 

C8Hi6-oxide Ketones C8H14 Pseudomonas oleovorans... 

Selenium dioxide can be used to oxidize ketones and aldehydes to a-dicarbonyl compounds. The reaction often gives high yields of products when there is a single type of CH2 group adjacent to the carbonyl group. In unsymmetrical ketones, oxidation usually occurs at the CH2 that is most readily enolized.255... 

GLYCOLYSIS FATTY ACID OXIDATION KETONE BODY USE PROTEIN DEGRADATION... 

Other mechanisms of ketone oxidation are also known and will be discussed in Chapter 8. Peracid, which is formed from aldehyde, oxidizes ketones with lactone formation (Bayer-Villiger reaction). 

Another factor complicating the situation in composition of peroxyl radicals propagating chain oxidation of alcohol is the production of carbonyl compounds due to alcohol oxidation. As a result of alcohol oxidation, ketones are formed from the secondary alcohol oxidation and aldehydes from the primary alcohols [8,9], Hydroperoxide radicals are added to carbonyl compounds with the formation of alkylhydroxyperoxyl radical. This addition is reversible. 

Another probable reaction of homolytic decomposition of ester hydroperoxide is the intramolecular interaction of the hydroperoxide group with the carbonyl group of ester with the formation of labile hydroxyperoxide succeeded the splitting of the weak O—O bond (see decomposition of hydroperoxides in oxidized ketones in Chapter 8). 

Sulfonic peracids oxidize ketones to lactones. The yields of the oxidation products are listed in Table 12.6. 

The secondary alcohols differ from the normal in yielding by oxidation ketones instead of acids. 

The method is also successful for carboxylic esters167 and N,N-disubstituted amides,168 and can be made enantioselective by the use of a chiral oxaziridine.169 Dimethyldioxirane also oxidizes ketones (through their enolate forms) to a-hydroxy ketones.169 ... 

Amminolysis of 3-halopyridines, generally a difficult reaction, can be effected via N-oxide derivatives. Thus, metalation-ary aldehyde condensation on 3-fluoropyridine (38) affords carbinols 122 which, upon standard sequential oxidation reactions, affords the N-oxide ketone 123 (Scheme 38) (84TH1). Treatment with dimethyl amine afforded the 3-amino derivative 124, thus completing this high overall yield sequence. 

Alkenes bound to cross-linked polystyrene can be epoxidized under conditions similar to those used in solution. The most commonly used reagent is m-chloroperbenzoic acid in DCM, but other reagents have also been used (Table 15.1). Because excess oxidant is usually required to furnish clean products, care must be taken with linkers or other functional groups prone to oxidation (ketones, amines, benzyl ethers, etc.). 

Alicyclic perfluoro ketones undergo similar oxidation reactions to aromatic fluoroaldehydes using hydrogen peroxide. The result of the reaction depends on the peroxide concentration a lower concentration of peroxide oxidizes ketones to a-hydroxy hydroperoxides,190 while concentrated hydrogen peroxide converts them into bis[l-hydroxy(perfluorocycloalkyl)]perox-ides. e.g. 5.72-191... 

In general, peroxomonosulfates have fewer uses in organic chemistry Uian peroxodisulfates. However, the triple salt is used for oxidizing ketones to dioxiianes, which in turn me useful oxidants in oiganic chemistry... 

Keywords silyl ether, tetrahydropyranyl ether, deprotection, wet alumina, chromium oxide, ketone, aldehyde... 

Our earlier work with Rh6(CO)i6 was the first example of using a transition metal carbonyl compound for catalyzed oxidations. We now find that Rh6(CO)16 is not unique in functioning as a homogeneous catalyst for oxidizing ketones. The dimer Re2(CO)10 is equally effective. The reaction mixture is homogeneous throughout the catalytic reaction. The carbonyl is not decomposed and can be recovered quantitatively at the end of the oxidation. This latter situation even prevails when the oxidations are carried out in the absence of carbon monoxide. Species characterization is done by isolation methods or by IR spectroscopy in the carbonyl region. 

A. Aldehydes have a proton attached to the carbonyl that i abstracted during oxidation. Ketones lack this proton and so cannot be oxidized,... 

Baeyer-Villiger oxidation ketone —> ester allows hydrolysis and ring cleavage... 

Most tissues oxidize the acetyl-CoA produced during P-oxidation to C02 and water via the TCA cycle. During fasting, however, the liver utilizes the intermediates of the TCA cycle as gluconeogenic substrates. Under these conditions, the Ever converts acetyl-CoA to ketone bodies (acetoacetate and P-hydroxybutyrate) (Figure 32-5). Most other peripheral tissues can oxidize ketone bodies by the pathway shown in the figure. After entering the mitochondria, acetoacetate reacts with succinyl-CoA to form acetoacetyl-CoA, a reaction that is catalyzed by 3-oxoacid-CoA transferase. Alternatively, acetoacetyl-CoA is formed by direct activation of acetoacetate by the enzyme acetoacetyl-CoA synthetase. Acetoacetyl-CoA is then cleaved to form two molecules of acetyl-CoA by acetoacetyl-CoA thiolase.As noted earlier in... 

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