Ketones industrial importance

Many low molecular weight aldehydes and ketones are important industrial chem icals Formaldehyde a starting material for a number of plastics is prepared by oxida tion of methanol over a silver or iron oxide/molybdenum oxide catalyst at elevated temperature... 

Ketones are an important class of industrial chemicals that have found widespread use as solvents and chemical intermediates. Acetone (qv) is the simplest and most important ketone and finds ubiquitous use as a solvent. Higher members of the aUphatic methyl ketone series (eg, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone) are also industrially significant solvents. Cyclohexanone is the most important cycHc ketone and is primarily used in the manufacture of y-caprolactam for nylon-6 (see Cyclohexanoland cyclohexanone). Other ketones find appHcation in fields as diverse as fragrance formulation and metals extraction. Although the industrially important ketones are reviewed herein, the laboratory preparation of ketones is covered elsewhere (1). 

Methyl Isobutyl Ketone. Methyl isobutyl ketone (MIBK) (4-methyl-2-pentanone), (CH2)2CHCH2COCH2, is an industrially important solvent which after methyl methacrylate and bisphenol A is the third largest tonnage product obtained from acetone. 

Complexes containing one binap ligand per ruthenium (Fig. 3.5) turned out to be remarkably effective for a wide range of chemical processes of industrial importance. During the 1980s, such complexes were shown to be very effective, not only for the asymmetric hydrogenation of dehydroamino adds [42] - which previously was rhodium s domain - but also of allylic alcohols [77], unsaturated acids [78], cyclic enamides [79], and functionalized ketones [80, 81] - domains where rhodium complexes were not as effective. Table 3.2 (entries 3-5) lists impressive TOF values and excellent ee-values for the products of such reactions. The catalysts were rapidly put to use in industry to prepare, for example, the perfume additive citronellol from geraniol (Table 3.2, entry 5) and alkaloids from cyclic enamides. These developments have been reviewed by Noyori and Takaya [82, 83]. 

Enol esters are distinct from other esters not because of a particular stability or lability toward hydrolases, but due to their hydrolysis releasing a ghost alcohol (an enol), which may immediately tautomerize to the corresponding aldehyde or ketone. A well-studied example is that of vinyl acetate (CH3-C0-0-CH=CH2), a xenobiotic of great industrial importance that, upon hydrolysis, liberates acetic acid (CH3-CO-OH) and acetaldehyde (CH3-CHO), the stable tautomer of vinyl alcohol [25], The results of two studies are compiled in Table 7.1, and demonstrate that vinyl acetate is a very good substrate of carboxylesterase (EC 3.1.1.1) but not of acetylcholinesterase (EC 3.1.1.7) or cholinesterase (EC 3.1.1.8). The presence of carboxylesterase in rat plasma but not in human plasma explains the difference between these two preparations, although the different experimental conditions in the two studies make further interpretation difficult. 

One of the most thoroughly investigated aldol condensations is the selfcondensation of acetone. This is an important industrial reaction for the production of diacetone alcohol (DA) (Scheme 11), which is valuable as a chloride-free solvent and an intermediate in the synthesis of industrially important products such as mesityl oxide (MO), isophorone, methyl isobutyl ketone, and 3,5-xylenol. The reaction is exothermic, with the yield of DA decreasing with increasing reaction temperature it is usually performed with NaOH or KOH as a basic catalyst 118). 

Palladium chloride or the chloropalladite ion catalyze the oxidation of olefins to aldehydes or ketones, presumably by forming unstable palladium-olefin complex intermediates 196). A reaction of great industrial importance is the palladium chloride/cupric chloride catalyzed oxidation of ethylene to acetaldehyde 195). The first stage is presumably the oxidative hydrolysis of ethylene,... 

In order to place later chapters in proper context, the first chapter offers a comprehensive overview of industrially important catalysts for oxidation and reduction reactions. Chapters 2 and 3 describe the preparation of chiral materials by way of the asymmetric reduction of alkenes and ketones respectively. These two areas have enjoyed a significant amount of attention in recent years. Optically active amines can be prepared by imine reduction using chiral catalysts, as featured in Chapter 4, which also discloses a novel reductive amination protocol. 

The remaining chapters deal with a variety of catalysts for effecting oxidation reactions. Chapter 5 describes three simple protocols for the controlled oxidation of primary or secondary alcohols. The importance of stereocontrolled epoxidation and hydroxylation reactions is reflected by the fact that Chapter 6, directed at this field, is one of the most extensive sections of the book. An interesting example of an enantioselective Baeyer-Villiger reaction is featured in Chapter 7, together with an industrially important ketone to enone conversion. Oxidative carbon-carbon... 

The synthesis of poly(vinyl acetals) (252) represents another example of generating a heterocycle, in this case the 1,3-dioxane nucleus, by application of a polymer modification reaction. Generally, the polymer modified is poly(vinyl alcohol) (180) or one of its copolymers. The 1,3-dioxane ring is generated (Scheme 122) by an acid-catalyzed acetalization reaction with an aldehyde, although ketones have also been reacted. A review (71MI11102) is available covering synthesis, properties and applications of the two most common and industrially important poly(vinyl acetals), poly(vinyl butyral) and poly(vinyl formal), as well as many other functional aldehydes that have been attached. 

One of the earliest uses of palladium(II) salts to activate alkenes towards additions with oxygen nucleophiles is the industrially important Wacker process, wherein ethylene is oxidized to acetaldehyde using a palladium(II) chloride catalyst system in aqueous solution under an oxygen atmosphere with cop-per(II) chloride as a co-oxidant.1,2 The key step in this process is nucleophilic addition of water to the palladium(II)-complexed ethylene. As expected from the regioselectivity of palladium(II)-assisted addition of nucleophiles to alkenes, simple terminal alkenes are efficiently converted to methyl ketones rather than aldehydes under Wacker conditions. 

How are industrially important ketones and aldehydes usually prepared ... 

Another important reaction typically proceeding in transition metal complexes is the insertion reaction. Carbon monoxide readily undergoes this process. Therefore, the insertion reaction is extremely important in organoiron chemistry for carbonylation of alkyl groups to aldehydes, ketones (compare Scheme 1.2) or carboxylic acid derivatives. Industrially important catalytic processes based on insertion reactions are hydroformylation and alkene polymerization. 

Both aldehydes and ketones are industrially important classes of chemicals. Aldehydes are reduced to make the corresponding alcohols and are used in the manufacture of resins, dyes, plasticizers, and alcohols. Some aldehydes are ingredients in perfumes and flavors. Several ketones are excellent solvents and are widely used for that purpose to dissolve gums, resins, laquers, nitrocellulose, and other substances. 

The dehydrogenation of alcohols was first studied by Ipatieff, who obtained the corresponding aldehydes or ketones by treatment of methyl, ethyl, isopropyl, isobutyl, and isoamyl alcohols with such catalysts as a platinum tube, zinc rods, and brass at suitable temperatures. The work of Sabatier and Senderens and later Constable and Palmer added to the understanding of this industrially important reaction. 

Structure of the Carbonyl Group 817 18-3 Nomenclature of Ketones and Aldehydes 818 18-4 Physical Properties of Ketones and Aldehydes 820 18-5 Spectroscopy of Ketones and Aldehydes 822 18-6 Industrial Importance of Ketones and Aldehydes 828 18-7 Review of Syntheses of Ketones and Aldehydes 829 18-8 Synthesis of Ketones from Carboxylic Acids 833 18-9 Synthesis of Ketones and Aldehydes from Nitriles 833... 

Oxyfluorides of Carbon. The literature on compounds containing only carbon, oxygen, and fluorine is extensive, numerous reviews are available, and many compounds are of industrial importance. Functional groups included under this classification are ketones, acid fluorides, ethers, epoxides, peroxides, and hypofluorites. Only very simple molecules are mentioned here as representatives of this large class of compounds. 

Oxidative addition of the H—Si bond is the most studied of the group IVB elements with the exception of carbon because of its relation to the industrially important catalytic hydrosilation of alkenes, alkynes and ketones. Compounds containing the Si—M bond are stable. While they are also synthesized by routes other than oxidative addition of the H—Si bond T H—Si, H—Ge and H—Sn add to transition metals ... 

The industrially important oxidation of alicyclic ketones to dicarboxylic acids (e. g., cyclohexanone to adipic acid) with oxygen has been successfully carried out. A solid/liquid system was used in the presence of catalytic amounts of PEG-400 and rhenium carbonyl [105]. The absence of one of the catalysts drastically decreases the yield. 

Another industrially important oxidation reaction, the Baeyer-Villiger oxidation [28] of ketones to esters by 35% aqueous hydrogen peroxide as oxidant, can also be advantageously conducted in a fluorous biphasic medium [29]. When the recyclable fluorous Letvis acidic tin(IV) complex (28) is used as catalyst very high selectivity of conversion of ketones to the corresponding esters or lactones is achieved (Scheme 3.11). 

Oxidation of olefinic substrates and, more specifically, of a-olefins to the corresponding ketones is more difficult to perform on ftmctionalized alkenes (e.g. 2-methyl-3-buten-2-ol, la) but is industrially important. These processes can be used to synthesize fine chemicals or... 

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