Catalytic oxidation of ethyl alcohol

From Ethyl Alcohol. Some acetaldehyde is produced commercially by the catalytic oxidation of ethyl alcohol. The oxidation is carried out by passing alcohol vapors and preheated air over a silver catalyst at 480°C (98). 

It was obtained commercially by catalytic oxidation of ethyl alcohol or by the hydration of acetylene (Scheme 17). 

The reaction considered was the catalytic oxidation of ethyl alcohol, dissolved in an aqueous alkaline solution, to acetic acid As oxidizing agent gaseous oxygen was used The catalyst employed was 0 5% Pd supported on alumina Table 5 gives the properties of the catalyst A previous kinetic study was carried out to measure the intrinsic chemical kinetic parameters of this reaction For this purpose a tubular, packed, flooded reactor was used (oxygen was supplied after its absorption in the solution before entering the reactor) Papers on this subject have already been published Baldi et al [2], [3] ... 

Baldi, G, S, Sicardi, I, Mazzarino, A, Gianetto and V. Specchia, Performance of a Laboratory Trickle Bed Reactor Catalytic Oxidation of Ethyl Alcohol, From Frontiers in Chem, React, Eng, edited by L,K, Daraiswamy and R,A, Mashelkar, 1984, vol. I, p,375-95 Wiley Eastern Ltd, New Delhi,... 

Concentration Effects. The reactivity of ethyl alcohol—water mixtures has been correlated with three distinct alcohol concentration ranges (35,36). For example, the chromium trioxide oxidation of ethyl alcohol (37), the catalytic decomposition of hydrogen peroxide (38), and the sensitivities of coUoidal particles to coagulation (39) are characteristic for ethyl alcohol concentrations of 25—30%, 40—60%, and above 60% alcohol, respectively. The effect of various catalysts also differs for different alcohol concentrations (35). 

In tonnage production, acetaldehyde may be manufactured by (1) the direct oxidation of ethylene, requiring a catalytic solution of copper chloride plus small quantities of palladium chloride, (2) the oxidation of ethyl alcohol with sodium dichromate, and (3) the dry distillation of calcium acetate with calcium formate. 

A copper catalysed click (azide-alkyne cycloaddition) reaction has been used to prepare a fluorous-tagged TEMPO catalyst (Figure 7.20). TEMPO is a stable organic free radical that can be used in a range of processes. In this case, its use in metal-free catalytic oxidation of primary alcohols to aldehydes using bleach as the terminal oxidant was demonstrated. The modified TEMPO can be sequestered at the end of the reaction on silica gel 60 and then released using ethyl acetate for reuse in further reactions in this way the TEMPO was used four times with no loss in activity. 

Methyl ethyl ketone 10 000 tonnes Catalytic oxidation of secondary butyl alcohol. 

An interesting observation has been made by Palmer 9 in connexion with the catalytic action on ethyl alcohol and isopropyl alcohol of metallic copper. When produced by the reduction of copper oxide, the metal was found to be active in promoting catalysis of ethyl alcohol to acetaldehyde but electrolytic copper was without effect on either alcohol. 

Catalytic dehydrogenations of primary alcohols are achieved by passing vapors of the alcohols at 275-350 °C over a catalyst, usually supported on asbestos, silica gel, pumice, etc. Ethyl alcohol is converted into acetaldehyde in 88% yield at 93% conversion by passing it at 275 °C over a mixture of oxides of copper, cobalt, and chromium on asbestos [1135]. 

The vapor-phase dehydrogenations just mentioned are applicable only to the preparation of aldehydes that tolerate such high temperatures. A catalytic oxidation of alcohols carried out by passing a current of air or oxygen through solutions of alcohols in solvents such as heptane [56] or ethyl acetate [55] in the presence of platinum [55, 56], or, better still, platinum dioxide [56], or active cobalt oxide [1136 is applicable even to alcohols that cannot be vaporized and that contain double bonds (equation 205) [56]. 

Tetra-A-propylammonium perruthenate (TRAP) has been known as a homogenous and versatile reagent for the catalytic oxidation of alcohols. One of the problems in the use of TRAP is its removal from the reaction ntixture. Ley et al. disclosed a system that permits recycling and reuse of TRAP [39]. They used TRAP and alcohol in CH Cl in the presence of l-ethyl-3-methyl-lH-imidazolium hexafluorophosphate ([emim][PFg]) and Et NBr accompanied with A-methylmorpholine A-oxide (NMO) as cooxidant. They demonstrated that both Et NBr and [anim][PF ] may be used to enable the recovery and reuse of TRAP. Also, performing the reaction under moderate oxygen pressure (30-40 bar) in dichloromethane and Et NBr at room temperature resulted in rapid and clean oxidation of sec-phenethyl alcohol. 

Acryclic acid is obtained by the catalytic oxidation of propylene and acrylates (methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate...) by alcohol esterification of the acid. The preparation of methacrylic acid involves the acidic hydrolysis of acetone cyanohydrin and methyl methacrylate is obtained by a similar process involving the methanolysis of acetone cyanohydrin. 

Samarium is used to dope calcium fluoride crystals for use in optical masers or lasers. Compounds of the metal act as sensitizers for phosphors excited in the infrared the oxide exhibits catalytic properties in the dehydration and dehydrogenation of ethyl alcohol. It is used in infrared absorbing glass and as a neutron absorber in nuclear reactors. The metal is priced at about 3.50/g (99.9%). Little is known of the toxicity of samarium therefore, it should be handled carefully. 

Catalytic oxidation of beech organosolv lignin in ionic liquid (l-ethyl-3-methylimidazolium trifluoromethanesulfonate) at 100°C and 8 MPa air in the presence of 20% Mn(N03)2 formed DMBQ 25 in 11.5% isolated yield and 21% selectivity. The amount of 25 formed under these conditions depended on the catalyst level. At 2% catalyst, the product slate shifted to a mixture of syringaldehyde, syringyl alcohol, and vanillin, with only trace amounts of DMBQ observed. The authors propose that DMBQ results from syringaldehyde oxidation [100]. 

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