Acetic acid/acetate ethanol oxidation

The formation of acetic acid by ethanol oxidation is a four-electron process, following the equation ... 

Cocoa beans Production of acetic acid (via ethanol oxidation) Temperature increase of the fermentation mass... 

Table 3 The avaage current efficiency (rji) and the average yield (Wj) of CO2, acetaldehyde, and acetic acid for ethanol oxidation on different catalyst electrodes in one eyele of potential sean in 1 M (or 0.1 M) ethanol + 0.5 M H2SO4 solution (error bar fw eurrent efficiency of CO2 and acetaldehyde <20%)...

To prepare acetic acid, aqueous ethanol is added gradually to a hot mixture of aqueous sodium dichromate and sulphuric acid. The oxidising mixture is now always in excess, and therefore the oxidation proceeds as far as possible moreover, the reaction is carried out under reflux, so that any acetaldehyde which volatilises is returned to the oxidising mixture. Hence the final product contains only a small amount of acetaldehyde. 

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... 

Steroidal 17-cyanohydrins are relatively stable towards chromium trioxide in acetic acid (thus permitting oxidation of a 3-hydroxyl group ) and towards ethyl orthoformate in ethanolic hydrogen chloride (thus permitting enol ether formation of a 3-keto-A system ). Sodium and K-propanol reduction produces the 17j -hydroxy steroid, presumably by formation of the 17-ketone prior to reduction. ... 

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. 

N 24.12% brick red solid mp, decomps when heated over 300°. Insol in w and the usual organic solvents as well as weak acids and alkalies. Comm prepn (Ref 3) is from thiocyanic acid and/or thiocyanates either by anodic oxidation or by interaction with hydrogen peroxide or halogens. The yield is impure because it contains both H and O. The S content varies between 45 and 55%. Lab prepn of the pure polymer is by reacting the Na salt of 5-chlor-3-mercapto 1,2,4-thiodiazols with either acet, ethanol or w (Refs 1 2)... 

Formally, in redox reactions there is transfer of electrons from a donor (the reductant) to the acceptor (the oxidant), forming a redox couple or pair. Oxidations in biological systems are often reactions in which hydrogen is removed from a compound or in which oxygen is added to a compound. An example is the oxidation of ethanol to acetaldehyde and then to acetic acid where the oxidant is NAD. catalyzed by alcohol dehydrogenase and acetaldehyde dehydrogenase, respectively. 

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. 

Another metal that has attracted interest for use as electrode material is rhodium, inspired by its high activity in the catalytic oxidation of CO in automotive catalysis. It is found that Rh is a far less active catalyst for the ethanol electro-oxidation reaction than Pt [de Souza et al., 2002 Leung et al., 1989]. Similar to ethanol oxidation on Pt, the main reactions products were CO2, acetaldehyde, and acetic acid. Rh, however, presents a significant better CO2 yield relative to the C2 compounds than Pt, indicating a... 

O-acetylophiocarpine (381) with ethyl chloroformate afforded the C-8—N cleaved urethane 382 in quantitative yield. Sequential treatment of 382 with silver nitrate, PCC, sodium hydroxide, and p-toluenesulfonic acid in ethanol furnished acetal 384, which was reduced with lithium aluminum hydride followed by hydrolysis to afford the hemiacetal 385. Oxidation of 385 with PCC provided (+ )-a-hydrastine (369). Similar treatment of O-acetylepi-ophiocarpine (386) afforded ( )-/J-hydrastine (368) however, in this case, C—N bond cleavage of 386 with ethyl chloroformate proceeded without regioselectivity. 

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 ... 

Other methods for the preparation of acetic acid are partial oxidation of butane, oxidation of ethanal -obtained from Wacker oxidation of ethene-, biooxidation of ethanol for food applications, and we may add the same carbonylation reaction carried out with a cobalt catalyst or an iridium catalyst. The rhodium and iridium catalysts have several distinct advantages over the cobalt catalyst they are much fester and fer more selective. In process terms the higher rate is translated into much lower pressures (the cobalt catalyst is operated by BASF at pressures of 700 bar). For years now the Monsanto process (now owned by BP) has been the most attractive route for the preparation of acetic acid, but in recent years the iridium-based CATTVA process, developed by BP, has come on stream. 

The oxidation of A-acyl-A-arylhydroxylamines with lead tetraacetate is very rapid even at very low temperatures. The product obtained is the corresponding aromatic nitroso compound. The most favorable reaction conditions involve propionic acid or ethanol-acetic acid as a solvent and reaction times of less than 10 sec at temperatures of —20°C or lower [87]. The use of ethanol-acetic acid is particularly recommended for several reasons. First, since the product is best isolated by steam distillation, the solvent assists in steamdistilling rapidly. The ethanol in the distillate helps minimize clogging of the condenser and also solubilizes small quantities of impurities that may be entrained. 

Lactose is readily fermented by lactic acid bacteria, especially Lactococcus spp. and Lactobacillus spp., to lactic acid, and by some species of yeast, e.g. Kluyveromyces spp., to ethanol (Figure 2.27). Lactic acid may be used as a food acidulant, as a component in the manufacture of plastics, or converted to ammonium lactate as a source of nitrogen for animal nutrition. It can be converted to propionic acid, which has many food applications, by Propionibacterium spp. Potable ethanol is being produced commercially from lactose in whey or UF permeate. The ethanol may also be used for industrial purposes or as a fuel but is probably not cost-competitive with ethanol produced by fermentation of sucrose or chemically. The ethanol may also be oxidized to acetic acid. The mother liquor remaining from the production of lactic acid or ethanol may be subjected to anaerobic digestion with the production of methane (CH4) for use as a fuel several such plants are in commercial use. 

OB to C02 —37.18% cryst mp 250—54°. V sol in acet, ethanol, eth, methanol and w. Prepn is by redn of Cu oxide with tetrazolediazonium hydroxide, or by treating K-tetrazole sulfonate with K hydroxide, dissolving the product in w and acidifying with dil sulfuric acid, The compd forms expl salts Mercuric Salt-a white solid which explds on heating. Silver Salt—Ag2 CON4 mw 299.79 N 18,69% white solid, explds violently on heating, but is insensitive to impact Refs 1) Beil 26,403 (121) 2) M. Freund... 

The oxidation of a-hydroxy acids by benzyltrimethylammonium tribromide (BTMAB) to the corresponding carbonyl compounds shows a substantial solvent isotope effect, A (H20)/A (D20) = 3.57, but no KIE for a-deuteromandelic acid.133 The oxidation of glucose by hypobromous acid is first order in glucose and the acid.134 [l,l-2H2]Ethanol shows a substantial kinetic isotope effect when oxidized by hexamethylenetetramine-bromine (HABR) in acetic acid to aldehyde.135 Kinetics of the oxidation of aliphatic aldehydes by hexamethylenetetramine-bromine have been studied by the same group.136 Dioxoane dibromide oxidizes y-tocopherol to 5-bromomethyl-y-tocopherylquinone, which spontaneously cyclizes to 5-formyl-y-tocopherol.137... 

During cheese production lactose is converted to lactic acid by starter lactic acid bacteria (LAB). Any unfermented lactose is converted to d- and L-lactate by nonstarter lactic acid bacteria (NSLAB) and racemization, respectively. Lactate can be oxidized by LAB in cheese to acetate, ethanol, formic acid, and carbon dioxide at a rate dependent on oxygen availability (McSweeney, 2004). Other pathways include conversion to propionate, acetate, water, and carbon dioxide by Propionibacterium spp. carbon dioxide and water by Penicillium spp. yeasts and butyric acid and hydrogen by Clostridium spp. The rate of lactose metabolism influences proteolysis and flavor formation (Creamer et al., 1985 Fox et al., 1990). 

Figure 3. Reflection spectrum of an oxidized aluminum film exposed to 0.010M acetic acid in ethanol also shown are the 1ETS peak positions (13)...

Small amounts of synthetic alcohol occur as by-products in various chemical processes, particularly production of acetic acid via butane oxidation. One company is producing about 12 million gallons of by-product ethanol at present but is not recovering it. 3... 

The LPS in the SDS-PAGE gel is oxidized with the solution containing 0.7% periodic acid, 40% ethanol, and 5% acetic acid at 22°C for 20 min without prior fixation. 

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