Air oxidation of alcohols

Air Oxidation of Alcohols to Esters via Bromine-Nitric Acid Catalysis... 

This system may be contrasted with that of Hay and Blanchard (7), who found that the Co(OAc)Br-catalyzed air oxidation of alcohols was a radical chain process, showing an induction period and requiring a high oxygen flow. 

Iwasawa T, Tokunaga M, Obora Y et al (2004) Homogeneous palladium catalyst suppressing Pd black formation in air oxidation of alcohols. J Am Chem Soc 126(21) 6554-6555... 

Noronha, G., Henry, P. M. Heterogenized polymetallic catalysts Part III. Catalytic air oxidation of alcohols by Pd(ll) complexed to a polyphenylene polymer containing P-di- and tri-ketone surface ligands. J. Mol. Catal. A Chemical 1997, 120, 75-87. 

Scheme 12. Air oxidation of alcohols effected by the copper enz5rme Galactose oxidase (GOase).

Daga N.S., Prasad C.V.S., Joshi J.B. Kinetics of hydrolysis and wet air oxidation of alcohol distillery waster. Indian Ghent. Eng., 1986 28 22-31. 

Secondary alcohols (C q—for surfactant iatermediates are produced by hydrolysis of secondary alkyl borate or boroxiae esters formed when paraffin hydrocarbons are air-oxidized ia the presence of boric acid [10043-35-3] (19,20). Union Carbide Corporation operated a plant ia the United States from 1964 until 1977. A plant built by Nippon Shokubai (Japan Catalytic Chemical) ia 1972 ia Kawasaki, Japan was expanded to 30,000 t/yr capacity ia 1980 (20). The process has been operated iadustriaHy ia the USSR siace 1959 (21). Also, predominantiy primary alcohols are produced ia large volumes ia the USSR by reduction of fatty acids, or their methyl esters, from permanganate-catalyzed air oxidation of paraffin hydrocarbons (22). The paraffin oxidation is carried out ia the temperature range 150—180°C at a paraffin conversion generally below 20% to a mixture of trialkyl borate, (RO)2B, and trialkyl boroxiae, (ROBO). Unconverted paraffin is separated from the product mixture by flash distillation. After hydrolysis of residual borate esters, the boric acid is recovered for recycle and the alcohols are purified by washing and distillation (19,20). 

The main processes for the manufacture of hydroxybenzaldehydes are based on phenol. The most widely used process is the saligenin process. Saligenin (2-hydroxybenzyl alcohol [90-01-7]) and 4-hydroxybenzyl alcohol [623-05-2] are produced from base-catalyzed reaction of formaldehyde with phenol (35). Air oxidation of saligenin over a suitable catalyst such as platinium or palladium produces sahcylaldehyde (62). 

The only industrially important processes for the manufacturing of synthetic benzaldehyde involve the hydrolysis of benzal chloride [98-87-3] and the air oxidation of toluene. The hydrolysis of benzal chloride, which is produced by the side-chain chlorination of toluene, is the older of the two processes. It is no longer utilized ia the United States. Other processes, including the oxidation of benzyl alcohol, the reduction of benzoyl chloride, and the reaction of carbon monoxide and benzene, have been utilized ia the past, but they no longer have any iadustrial appHcation. 

Bode acid catalyzes the air oxidation of hydrocarbons and increases the yield of alcohols by forming esters that prevent further oxidation of hydroxyl groups to ketones and carboxyHc acids (see Hydrocarbon oxidation). 

Cyclohexanol. This alcohol is produced commercially by the catalytic air oxidation of cyclohexane or the catalytic hydrogenation of phenol. 

Recently, great advancement has been made in the use of air and oxygen as the oxidant for the oxidation of alcohols in aqueous media. Both transition-metal catalysts and organocatalysts have been developed. Complexes of various transition-metals such as cobalt,31 copper [Cu(I) and Cu(II)],32 Fe(III),33 Co/Mn/Br-system,34 Ru(III and IV),35 and V0P04 2H20,36 have been used to catalyze aerobic oxidations of alcohols. Cu(I) complex-based catalytic aerobic oxidations provide a model of copper(I)-containing oxidase in nature.37 Palladium complexes such as water-soluble Pd-bathophenanthroline are selective catalysts for aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic... 

Tc2(CH3C00)4](Tc04)2. This compound was obtained by the slow oxidation of alcoholic solutions of the intermediate products of the synthesis of [Tc2(CH3COO)4Cl] and K2[Tc2(Ac)4C1]2 in air [58]. The oxidation yields several red transparent crystals of the regular octahedral form. 

Such reactions are also possible in vitro, as several mild oxidizing agents are at hand nowadays. Thus, the Dess-Martin periodinane (DMP) [50] has been proven to be a versatile and powerful reagent for the mild oxidation of alcohols to the corresponding carbonyl compounds. In this way, a series of new iodine(V)-mediated reactions has been developed which go far beyond simple alcohol oxidation [51], Ni-colaou and coworkers have developed an effective DM P-mediated domino polycy-clization reaction for converting simple aryl amides, urethanes and ureas to complex phenoxazine-containing polycycles. For example, reaction of the o-hydroxy anilide 7-101 with DMP (2 equiv.) in refluxing benzene under exposure to air led to polycycle 7-103 via 7-102 in a yield of 35 % (Scheme 7.28) [52]. 

A prime advantage of such biphasic systems is that the catalyst resides in one phase and the starting materials and products are in the second phase, thus providing for easy recovery and recycling of the catalyst by simple phase separation. A pertinent example is the aerobic oxidation of alcohols catalyzed by a water-soluble Pd-bathophenanthroline complex (Figure 9.5). The only solvent used is water, the oxidant is air, and the catalyst is recycled by phase separation. 

There are several other routes to acetone of minor importance air oxidation of IPA reaction between IPAand acrolein for the production of allyl alcohol, with acetone as the by-product vapor phase oxidation of butane coproduction when IPA is oxidized yielding acetone and H2O2, hydrogen peroxide, the principal ingredient of bleach and by-product production from the manufacture of methyl ethyl ketone. 

The reactions can be carried out in aqueous solutions or biphasic mixtures of the substrates with no additional solvent, in the presence of NaOAc (pH s 11.5) at 100 °C. At this pH the resting state of the catalyst is probably the dinuclear species depicted on Scheme 8.1, which falls apart upon coordination of the substrate alcohol. In this respect the catalyst system as very similar to that for the oxidation of terminal olefins [10,11]. Good results were obtained with 30 bar of air, however, an 8 % O2/N2 mixture can also be used, which further improves the safety of the process. Recycling of the aqueous catalyst solution is possible and is especially easy in case of biphasic reaction mixtures. Taking all these features, this Pd-catalyzed oxidation of alcohols is a green process, indeed. 

Cyclohexanol and cyclohexanone are made by the air oxidation of cyclohexane (81%) with a cobalt(II) naphthenate or acetate or benzoyl peroxide catalyst at 125-160°C and 50-250 psi. Also used in the manufacture of this mixture is the hydrogenation of phenol at elevated temperatures and pressures, in either the liquid or vapor phase (19%). The ratio of alcohol to ketone varies with the conditions and catalysts. 

The measurement of open circuit potential of the catalyst during the liquid phase oxidation of alcohols provides a unique insight into the redox processes taking place on the catalyst surface. A Pt catalyst stored in air contains surface oxides and in an aqueous Na2C03 solution it behaves as an oxygen electrode. Its potential is 250-280 mV when referred to a Ag/AgCl/KCl(3 ) electrode (Figure 3). When the catalyst is... 

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