Oxidation of Alcohols and Phenols

Perhaps the most valuable reaction of alcohols is their oxidation to give carbonyl compounds—the opposite of the reduction of carbonyl compounds to give alcohols. Primary alcohols yield aldehydes or carboxylic acids, secondary alcohols yield ketones, but tertiary alcohols don t normally react with 

Primary alcohols are oxidized to either aldehydes or carboxylic acids, depending on the reagents chosen and the conditions used. Older methods were often based on Cr(VI) reagents such as CrOa or Na2Cr207, but a more 

Most other commonly used oxidizing agents, such as chromium trioxide (CrOa) in aqueous acid, oxidize primary alcohols directly to carboxylic acids. An aldehyde is involved as an intermediate in this reaction hut can t usually be isolated because it is further oxidized too rapidly. 

Secondary alcohols are easily oxidized to give ketones. For a sensitive or costly alcohol, the Dess-Martin procedure is often used because the reaction is nonacidic and occurs at lower temperatures. For a large-scale oxidation, however, an inexpensive reagent such as Na2Cr207 in aqueous acetic acid might be used. 

CHAPTER 13 ALCOHOLS, PHENOLS, AND THIOLS ETHERS AND SULEIDES 

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Several organohypervalent iodine reagents have been used for the oxidation of alcohols and phenols such as iodoxybenzene, o-iodoxybenzoic acid (IBX), bis(trifluoroa-cetoxy)iodobenzene (BTI), and Dess-Martin periodinane etc. But the use of inexpensive iodobenzene diacetate (IBD) as an oxidant, however, has not been fully exploited. Most of these reactions are conducted in high boiling DMSO or toxic acetonitrile media that results in increased burden on the environment. 

Organohypervalent iodine reagents such as iodoxybenzene, o-iodoxybenzoic acid (IBX), bis(trifluoroacetoxy)iodobenzene (BTI), and Dess-Marhn periodinane have been used for the oxidation of alcohols and phenols. Most of these reactions are conducted in high-boiling DMSO or relahvely toxic acetonitrile, which increase the burden on the environment. Further, the use of inexpensive iodobenzene diacetate (IBD) as an oxidant has not been fully exploited. Varma et al. have reported the first use of supported iodobenzene diacetate as an oxidant. In this novel oxidative protocol, alumina-supported IBD under solvent-free conditions rapidly converts alcohols to the corresponding carbonyl compounds in almost quantitative yields. The use of alumina as a support improved the yields markedly as compared to neat IBD (Scheme 2.2-40). 1,2-Benzenedimethanol, however, undergoes cyclization to afford l(3H)-isobenzofuranone [116]... 

Kolbe and Hofer-Moest reactions Oxidation of amines Oxidation of amides Oxidation of alcohols and phenols Oxidation of ethers Oxidation of oximes, nitroalkanes, hydrazines Electrocoating... 

Zinc oxide Carboxylic acids, partial subtraction of alcohols and phenols. 

The oxidative carbonylation of alcohols and phenols to carbonates can be catalyzed by palladium or copper species [154-213]. This reaction is of particular practical importance, since it can be developed into an industrial process for the phosgene-free synthesis of dimethyl carbonate (DMC) and diphenyl carbonate (DPC), which are important industrial intermediates for the production of polycarbonates. Moreover, DMC can be used as an eco-friendly methylation and carbonylation agent [214,215]. The industrial production of DMC by oxidative carbonylation of methanol has been achieved by Enichem [216] and Ube [217]. 

By Reactions of Metal Hydroxides and Oxides with Alcohols and Phenols 338... 

Absolute kinetic data have been reported for four of the characteristic bimolecular reactions of disilenes 1,2-addition of alcohols and phenols (equation 72), [2 + 2]-cycloaddition of ketones (equation 73), [2 +4]-cycloaddition of aliphatic dienes (equation 74) and oxidation with molecular oxygen (equation 75). As with silenes, the addition of alcohols has been studied in greatest detail. 

This chapter highlights the ruthenium-catalyzed dehydrogenative oxidation and oxygenation reactions. Dehydrogenative oxidation is especially useful for the oxidation of alcohols, and a variety of products such as ketones, aldehydes, and esters can be obtained. Oxygenation with oxo-ruthenium species derived from ruthenium and peroxides or molecular oxygen has resulted in the discovery of new types of biomi-metic catalytic oxidation reactions of amines, amides, y3-lactams, alcohols, phenols, and even nonactivated hydrocarbons tmder extremely mild conditions. These catalytic oxidations are both practical and useful, and ruthenium-catalyzed oxidations will clearly provide a variety of futrue processes. 

Selection of a suitable chemical emulsion breaker and dosage is crucial. A particular demulsifier may be effective and efficient for one emulsion yet entirely unsatisfactory for another. Contemporary demulsifiers are formulated with polymeric chains of ethylene and propylene oxides of alcohol, alkyl phenols, amino compounds, and resinous materials that have hydroxy acceptor groups. Each of these polymers is carefully formulated to yield a molecule with a particular affinity for water. Demulsifier dosage is also important excessive demulsifier addition can inhibit the efficiency of emulsion breakdown. 

Soaps and detergents are surfactants used in cleaning.260 Soaps are salts of fatty acids (e.g., sodium stearate). Detergents are salts of sulfonic acids, quaternary ammonium salts, tertiary amine oxides, ethylene oxide adducts of alcohols, and phenols.261 Their use in cleaning to replace chlorinated solvents262 was covered in Chap. 3, Sec. VII. (See also the use of hydrogen peroxide,263 ethyl lactate,264 and ultrasound265 to clean process equipment.) Some other environmental aspects of their use will be covered here briefly. 

Acyloxy- and acylthiopyrazines are convenient acylation reagents for benzylamine, aniline, pyrrolidine, and related compounds (see Section 6.03.8.3). The acylthio compounds are also useful for acylation of alcohols and phenols. Pyrazinyl alkyl sulfoxides (see Section 6.03.8.4) give aldehydes and ketones by treatment with TFAA <91H(32)937>. The pyrazinium chlorochromate salt (181) is formed by addition of chromium(VI) oxide to a solution of pyrazine in hydrochloric acid, and it has proved to be more effective for the oxidation of aliphatic and allyl alcohols to the aldehydes than pcc <83H(20)2029>. 

The oxidation of alcohols, including phenols, may also be catalyzed by zinc oxide and light. Markam and coworkers - oxidized glycerol, benzyl alcohol, and the first seven aliphatic alcohols at room temperature with light of 3660 A. in the presence of zinc oxide. None of the alcohols studied absorb at this wavelength. 

Matsuchita et al. [38] have used RuCoAl hydrotalcites for highly efUcient oxidation of alcohols and aromatic compounds using molecular oxygen. Zhu et at. [39] studied hydroxylation of phenol in the liquid phase over copper containing (CuAI-HT) hydrotalcites. The results inferred that among the catalysts studied, the catalyst with Cu/AI 3 atomic ratio showed the highest activity for the conversion of phenol and activity of the fresh (uncalcined) samples was higher than the calcined samples. Ternary hydrotalcites such as Ni(Mg)Al, Mg(Mn)AI, have also been found active for various oxidative transformation reactions [40]. 

The reactivity of alcohols and phenols with ethylene oxide varies in the order primary > alkyl phenol > secondary > tertiary [13]. However, tertiary alcohols can be made to react with ethylene oxide [14]. Some linear secondary alcohols have been reacted with ethylene oxide to give nonionic surfactants (Union Carbide) [15]. Some typical alcohols used to give the nonionic surfactants (polyoxyethylenealkyl ethanols) are allyl, lauryl, cetyl, stearyl, tridecyl, myristyl, C12-C15 primary linear, tallow, and trimetfaylnonyl [16]. 

The reaction with sodium sulfite or bisulfite (5,11) to yield sodium-P-sulfopropionamide [19298-89-6] (C3H7N04S-Na) is very useful since it can be used as a scavenger for acrylamide monomer. The reaction proceeds very rapidly even at room temperature, and the product has low toxicity. Reactions with phosphines and phosphine oxides have been studied (12), and the products are potentially useful because of thek fire retardant properties. Reactions with sulfide and dithiocarbamates proceed readily but have no appHcations (5). However, the reaction with mercaptide ions has been used for analytical purposes (13)). Water reacts with the amide group (5) to form hydrolysis products, and other hydroxy compounds, such as alcohols and phenols, react readily to form ether compounds. Primary aUphatic alcohols are the most reactive and the reactions are compHcated by partial hydrolysis of the amide groups by any water present. 

The chemical resistance of the linear polymers is also very good. Resistant to most acids, aqueous bases, hydrocarbons, most halogenated hydrocarbons, alcohols and phenols, they are attacked by concentrated sulphuric acid, formic acid, some amines, benzaldehyde, nitromethane and a few other reagents. They will dissolve in 1-chloronaphthalene at elevated temperatures but in general have excellent solvent resistance. The polymer is cross-linked by air oxidation at elevated temperatures. 

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