Alcohols ethanol oxidation

Many biological processes involve oxidation of alcohols to carbonyl compounds or the reverse process reduction of carbonyl compounds to alcohols Ethanol for example is metabolized m the liver to acetaldehyde Such processes are catalyzed by enzymes the enzyme that catalyzes the oxidation of ethanol is called alcohol dehydrogenase... 

Currently, almost all acetic acid produced commercially comes from acetaldehyde oxidation, methanol or methyl acetate carbonylation, or light hydrocarbon Hquid-phase oxidation. Comparatively small amounts are generated by butane Hquid-phase oxidation, direct ethanol oxidation, and synthesis gas. Large amounts of acetic acid are recycled industrially in the production of cellulose acetate, poly(vinyl alcohol), and aspirin and in a broad array of other... 

In fermentation for the production of acetic acid, ethyl alcohol is used in an aerobic process. In an ethanol oxidation process, the biocatalyst Acetobacter aceti was used to convert ethanol to acetic acid under aerobic conditions. A continuous fermentation for vinegar production was proposed for utilisation of non-viable A. aceti immobilised on the surface of alginate beads. 

Ethanol is oxidized by alcohol dehydrogenase (in the presence of nicotinamide adenine dinucleotide [NAD]) or the microsomal ethanol oxidizing system (MEOS) (in the presence of reduced nicotinamide adenine dinucleotide phosphate [NADPH]). Acetaldehyde, the first product in ethanol oxidation, is metabolized to acetic acid by aldehyde dehydrogenase in the presence of NAD. Acetic acid is broken down through the citric acid cycle to carbon dioxide (CO2) and water (H2O). Impairment of the metabolism of acetaldehyde to acetic acid is the major mechanism of action of disulfiram for the treatment of alcoholism. 

Anton RF, Pettinati H, Zweben A, et al A multi-site dose ranging study of nalmefene in the treatment of alcohol dependence. J Clin Psychopharmacol 24 421 28, 2004 Aragon CM, Stotland LM, Amit Z Studies on ethanol-brain catalase interaction evidence for central ethanol oxidation. Alcohol Clin Exp Res 15 165-169, 1991 Arizzi MN, Correa M, Betz AJ, et al Behavioral effects of intraventricular injections of low doses of ethanol, acetaldehyde, and acetate in rats studies with low and high rate operant schedules. Behav Brain Res 147 203—210, 2003 Azrin NH, Sisson RW, Meyers R, et al Alcoholism treatment by disulfiram and community reinforcement therapy. J Behav Ther Exp Psychiatry 13 105—112, 1982 Babor TF, Kranzler HR, Lauerman RL Social drinking as a health and psychosocial risk factor Anstie s limit revisited, in Recent Developments in Alcoholism, Vol 5. Edited by Galanter M. New York, Plenum, 1987, pp 373 02... 

Chaudhuri et al. (216) reported that the dinuclear bis(phenoxyl)dicopper(II) species [Cu2(Ls )2]Cl2 (Fig- 30) reacts under anaerobic conditions in dry THF in a stoichiometric fashion with primary and secondary alcohols (ethanol, benzyl alcohol, 2-propanol, diphenylcarbinol, and 2-butanol) with formation of two different products, namely, aldehydes (or ketones) and 1,2-diols (and/or other oxidative C— C coupling products). 

Recently, two reports (218, 219) appeared showing that (iminosemiqui-nonato)copper(II) complexes also catalyze the aerobic oxidation of primary alcohols (ethanol, benzyl alcohol) to the corresponding aldehydes and H202. Complexes J and K shown in Fig. 33 have been isolated as active catalysts and the former has been characterized by X-ray crystallography. Detailed mechanistic studies have been performed that again show the close resemblance to GO. 

Izumi and Urabe [105] found first that POM compounds could be entrapped strongly on active carbons. The supported POMs catalyzed etherization of ferf-butanol and n-butanol, esterification of acetic acid with ethanol, alkylation of benzene, and dehydration of 2-propanol [105], In 1991, Neumann and Levin [108] reported the oxidation of benzylic alcohols and amines catalyzed by the neutral salt of Na5[PV2Mo10O40] impregnated on active carbon. Benzyl alcohols were oxidized efficiently to the corresponding benzaldehydes without overoxidation ... 

Reactions alcohols, 29 36-49 adsorption, 29 36-37 clean surfaces, 29 37-38 ethanol oxidation, 29 44—48 methanol oxidation, 29 38-44 oxidation on copper and silver, 29 38-48 oxidation reaction, silver, 29 48-49 base-catalyzed, of hydrocarbons, 12 117 free radical mechanism in, of hydrogen peroxide, 4 343... 

Chromium(III) catalyses the cerium(IV) oxidation of primary and secondary alcohols in a mixture of H2SO4 and HC104. Kinetic results have been interpreted in terms of the formation of chromium(IV) in a reversible equilibrium, which forms a complex with the alcohol. Internal oxidation-reduction occurs in a rate-determining step to give aldehyde or ketone and regenerate the catalyst in the +3 state. The oxidation of ethanol under similar conditions has also been studied. ... 

The final reactions to be considered in the metabolism of ethanol in the liver are those involved in reoxidation of cytosolic NADH and in the reduction of NADP. The latter is achieved by the pentose phosphate pathway which has a high capacity in the liver (Chapter 6). The cytosolic NADH is reoxidised mainly by the mitochondrial electron transfer system, which means that substrate shuttles must be used to transport the hydrogen atoms into the mitochondria. The malate/aspartate is the main shuttle involved. Under some conditions, the rate of transfer of hydrogen atoms by the shuttle is less than the rate of NADH generation so that the redox state in the cytosolic compartment of the liver becomes highly reduced and the concentration of NAD severely decreased. This limits the rate of ethanol oxidation by alcohol dehydrogenase. 

Ethanol oxidation, via alcohol dehydrogenase, reduces testosterone secretion, due to a high NADH/NAD ratio is the Leydig cells in the testes. 

In addition to alcohol dehydrogenase, ethanol can be oxidized to acetaldehyde by the microsomal mixed-function oxidase system (cytochrome P450 2 El), as illustrated in Figure 35.1. Although this microsomal ethanol-oxidizing system probably has minor impor-... 

Preparation of alkoxy alcohol Ethylene oxide is a symmetrical epoxide, which reacts with sodium methoxide to produce 2-methoxy-ethanol, after the hydrolytic work-up. 

Metabolism of ethanol by alcohol dehydrogenase and the microsomal ethanol-oxidizing system (MEOS). Alcohol dehydrogenase and aldehyde dehydrogenase are inhibited by fomepizole and disulfiram, respectively. NAD +, nicotinamide adenine dinucleotide NADPH, nicotinamide adenine dinucleotide phosphate. 

The pathogenesis of alcoholic liver disease is a multifactorial process involving metabolic repercussions of ethanol oxidation in the liver, dysregulation of fatty acid oxidation and synthesis, and activation of the innate immune system by a combination of direct effects of ethanol and its metabolites and by bacterial endotoxins that access the liver as a result of ethanol-induced changes in the intestinal tract. Tumor necrosis factor- , a proinflammatory cytokine that is consistently... 

Propanol oxidation under mild conditions takes place with high selectivity. No products other than acetone were observed in the ATR spectra recorded in situ. The situation is more complex for the oxidation of primary alcohols such as ethanol. The first oxidation step produces acetaldehyde, which is prone to further reactions, as is apparent in the ATR spectra. Figure 20, left, shows ATR spectra recorded in situ during ethanol oxidation. Figure 20, right, shows some signals as a function of time. The experiment was performed in a manner similar to that of the one... 

Type 4A sieves. The pore size is about 4 Angstroms, so that, besides water, the ethane molecules (but not butane) can be adsorbed. Other molecules removed from mixtures include carbon dioxide, hydrogen sulphide, sulphur dioxide, ammonia, methanol, ethanol, ethylene, acetylene, propylene, n-propyl alcohol, ethylene oxide and (below -30°) nitrogen, oxygen and methane. The material is supplied as beads, pellets or powder. 

Figure 7.85 The metabolism of methanol. Abbreviations. ADH, alcohol dehydrogenase MEOS, microsomal ethanol-oxidizing system ALDH, aldehyde dehydrogenase THF, tetrahydrofolate.

It must be stressed that there is still a fair chance of arriving at electrocatalysts that would achieve reasonable anode potentials (say +0.3 V vs RHE) at technically acceptable current densities (say 0.3 to 0.4 A/cm2). The situation for the next higher alcohol, ethanol, however, is almost hopeless. Any work aimed at developing catalysts for anodic oxidation of the much more inert hydrocarbons at low temperatures will certainly be frustrated. 

Several of the B vitamins function as coenzymes or as precursors of coenzymes some of these have been mentioned previously. Nicotinamide adenine dinucleotide (NAD) which, in conjunction with the enzyme alcohol dehydrogenase, oxidizes ethanol to ethanal (Section 15-6C), also is the oxidant in the citric acid cycle (Section 20-10B). The precursor to NAD is the B vitamin, niacin or nicotinic acid (Section 23-2). Riboflavin (vitamin B2) is a precursor of flavin adenine nucleotide FAD, a coenzyme in redox processes rather like NAD (Section 15-6C). Another example of a coenzyme is pyri-doxal (vitamin B6), mentioned in connection with the deamination and decarboxylation of amino acids (Section 25-5C). Yet another is coenzyme A (CoASH), which is essential for metabolism and biosynthesis (Sections 18-8F, 20-10B, and 30-5A). 

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