Acetaldehyde, oxidation

Oxidation. Acetaldehyde is readily oxidised with oxygen or air to acetic acid, acetic anhydride, and peracetic acid (see Acetic acid and derivatives). The principal product depends on the reaction conditions. Acetic acid [64-19-7] may be produced commercially by the Hquid-phase oxidation of acetaldehyde at 65°C using cobalt or manganese acetate dissolved in acetic acid as a catalyst (34). Liquid-phase oxidation in the presence of mixed acetates of copper and cobalt yields acetic anhydride [108-24-7] (35). Peroxyacetic acid or a perester is beheved to be the precursor in both syntheses. There are two commercial processes for the production of peracetic acid [79-21 -0]. Low temperature oxidation of acetaldehyde in the presence of metal salts, ultraviolet irradiation, or osone yields acetaldehyde monoperacetate, which can be decomposed to peracetic acid and acetaldehyde (36). Peracetic acid can also be formed directiy by Hquid-phase oxidation at 5—50°C with a cobalt salt catalyst (37) (see Peroxides and peroxy compounds). Nitric acid oxidation of acetaldehyde yields glyoxal [107-22-2] (38,39). Oxidations of /)-xylene to terephthaHc acid [100-21-0] and of ethanol to acetic acid are activated by acetaldehyde (40,41). 

Figure 8.42. Effect of Ag/YSZ catalyst potential and work function on the rates of formation of ethylene oxide, acetaldehyde, and C02 at low Po/Pc2h4 ratios. T=260°C P=500 kPa 3.5% 02 9.8% C2H4 , C2H40 , CH3CHO , C02. Reprinted with permission from Academic Press.

C19-0083. Dichromate ions, C r2 0-j, oxidize acetaldehyde, CH3 CHO, to acetic acid, CH3 CO2 H, and are reduced to Cr . The reaction takes place in acidic solution. Balance the redox reaction and determine how many moles of electrons are required to oxidize 1.00 g of acetaldehyde. What mass of sodium dichromate would be required to deliver this many electrons ... 

In degree 2 only reactivity degrees are treated vis- i-vis exothermic polymerization in particular and addition reactions on the double bond (ethylene, butadiene, styrene, propylene), easy peroxidation (isopropyl oxide, acetaldehyde), hydrolysis (acetic anhydride). Possibly only propionitrile and substances with code 0 have an actual NFPA stability code. Every time one has to deal with the NFPA code one has to interpret it after carefully reading the paragraphs in Part Two. 

Hoechst-Shawinigan A catalytic process for oxidizing acetaldehyde directly to acetic anhydride, using oxygen. See Shawinigan. 

Rhone-Poulenc/Melle Bezons A process for making acetic acid by oxidizing acetaldehyde with oxygen in air. Removal of the nitrogen would incur a cost penalty. 

Double bonds characterize the basic building blocks of the petrochemical business. Ethylene, for example, is the chemical compound used to make vinyl chloride, ethylene oxide, acetaldehyde, ethyl alcohol, styrene, alpha olefins, and polyethylene, to name only a few. Propylene and benzene, the other big-volume building blocks, also have the characteristic double bonds. 

Oxygen has major uses in the chemical industry too. It is used to oxidize methane, ethylene, and other hydrocarbons. Oxidation of methane produces synthesis gas. Ethylene oxidation yields products such as ethylene oxide, acetaldehyde, and acetic acid. Oxygen also is used in making many commercial inorganic compounds including various metal oxides, oxoacids, and 0x0-salts. 

Divalent Metal Molybdates. Except for the first point, the conversion of ethane did not change in the conditioning period at 823 K and it lay in the same range as for the N2O as oxidant. The main product was ethylene the selectivity of its foimation mai kedly exceeded that obtained with N2O as oxidant. Acetaldehyde was formed with 4.8% and 6.8% selectivity on the Mg and Zn salts. As a result, the yields for ethylene and acetaldehyde were much higher than in the case of N2O oxidation (Figure 5). Other hydrocarbons and alcohols were also detected in very small concentrations, with less than 1% selectivity. 

Its vapor is green and burns with a violet flame sol in w, ale eth. Was first prepd in 1881 (Refs 1 2) by oxidizing acetaldehyde with nitric acid. This and ocher methods are described by Curme Johnston (Ref 4, pp 125-26)... 

Ethyl alcohol has been made by the hydration of ethylene (9) since 1930. Like isopropyl alcohol, part of the output is used as a solvent, but most is converted to other oxygenated chemicals. Its most important raw material use is conversion to acetaldehyde by catalytic air oxidation. Acetaldehyde, in turn, is the raw material source of acetic acid, acetic anhydride, pentaerythritol, synthetic n-butyl alcohol (via aldol condensation), butyraldehyde, and other products. Butyraldehyde is the source of butyric acid, polyvinyl butyral resin, and 2-ethylhexanol (octyl alcohol). The last-named eight-carbon alcohol is based on the aldol condensation of butyraldehyde and is used to make the important plasticizer di-2-ethylhexyl phthalate. A few examples of the important reactions of acetaldehyde are as follows ... 

Its chemical stability is fairly high and only an insignificant amount decomposes on prolonged boiling in water. Boiling in dilute sulphuric acid causes decomposition with the evolution of nitrous oxide, acetaldehyde and ethylene glycol. 

The oxidation of acetaldehyde to acetic acid has been studied with NAD-linked ALDH purified from human, rat and Syrian hamster liver (Klyosov et al., 1996). The mitochondrial enzymes from these species have very similar kinetic properties, whereas human cytosolic ALDHl has a value of about 180 pM, compared with 15 pM and 12 pM for rats and hamsters, respectively. Apparently, in human liver, only mitochondrial ALDH oxidizes acetaldehyde at physiological concentrations, whereas both mitochondrial and cytosolic ALDHs of rodents can participate in acetaldehyde metabolism. The rodent cytosolic ALDHs are at least 10 times more sensitive that the human enzyme to inhibition by disulfiram. 

The amounts of acetaldehyde produced approached a maximum with time and the amounts of nitrous oxide also decreased with the % conversion. Since carbon monoxide, carbon dioxide, and methanol increased with time, it seems likely that, parallel to the role of formaldehyde in azomethane oxidation, acetaldehyde was a reactive intermediate. Acetaldehyde removed by such a reaction as... 

A considerable wood hydrolysis industry with rather old traditions is located in the Soviet Union. The main fermentation product based on hexoses in wood hydrolyzates is ethyl alcohol, but pentoses and aliphatic acids can also be utilized in the production of proteins (see Section 10.2.3). A variety of chemicals, including ethylene, ethylene oxide, acetaldehyde, and acetic acid, can be produced from ethyl alcohol. One interesting future application of ethyl alcohol concerns its use as a motor fuel mixed with gasoline (gasohol). 

Certain drugs inhibit non-microsomal metabolic pathways. Metronidazole, like disulfiram, inhibits aldehyde dehydrogenase, the enzyme that normally oxidizes acetaldehyde to acetic acid in the metabolic pathway for ethanol. Allopurinol inhibits xanthine oxidase, the enzyme that catalyses the oxidation of hypoxanthine to xanthine and xanthine to uric acid. Because azathioprine and 6-mercaptopurine are metabolized by xanthine oxidase, the dosage of these drugs (synthetic xanthine analogues), when used concomitantly with... 

Other processes (J), which involve more expensive and reactive organic feeds (ethylene oxide, acetaldehyde) and oxidants (NO) (Eqs. 10-12), were also... 

Heteropolyacids can be very useful in oxidation reactions. In contrast with metal chelate catalysts that usually become oxidized and deactivated eventually, the heteropolyacids are extremely stable to oxidation. Acetaldehyde is produced commercially from ethylene by the Wacker reaction with a palladium(II) chloride catalyst, copper(II) chloride, oxygen, and water. The corrosive conditions are a disadvantage of the process. Catalytica Inc. has devised a process (6.55) that uses only 1% as much palladium and chloride as the usual process. It uses a small amount of palladium (II) chloride with a partial sodium salt of phosphomolybdovanadic acid.287... 

AMYL ETHYL KETONE (541-85-5) CsH, 0 C2H5C0CH2CH(CH3)CH2CH3 Flammable liquid. Forms explosive mixture with air (flash point 109°F/43°C cc 135°F/57°C oc Fire Rating 2). Violent reaction with strong oxidizers, acetaldehyde. 

---