Oxygenative dehydrogenation

Table 4-1 Products from the Iron(II)-Induced Mono-oxygenation, Dehydrogenation, and Dioxygenation of Organic Substrates (PH) by HOOH in Dry Acetonitrile ... 

REACTIVITY OF DIOXYGEN AND ITS ACTIVATION FOR SELECTIVE DIOXYGENATION, MONO-OXYGENATION, DEHYDROGENATION, AND AUTO-OXIDATION OF ORGANIC SUBSTRATES AND METALS (CORROSION)... 

As for the role of bipy and py, subsequent work has established that they are not essential for the oxygenation (dehydrogenation) to occur. Iron(III) salts, like chloride, nitrate or perchlorate, hydrated or anhydrous, are effective catalysts for 3,5-DTBC oxidation in THF or DMF [108]. 3,5-DTBQ is the predominant product but intradiol cleavage to 15, DBMUA and 53 (Scheme 7) also takes place. Additives like py. 

Interest in catechol as a substrate for oxidation stems from the discovery of its oxidative ring cleavage by the first oxygenase enzyme pyrocatechase. 3,5-Di-t-butylcatechol (3,5-DTBC) has been widely used as a substrate in various catalytic oxygenations (dehydrogenations). Most of the mechanistic information now available on various catalyst systems has been obtained from studies on 3,5-DTBC oxidation. 

Oxygenation/dehydrogenation of bromophenylhydrazone (63) in the presence of Co(salpr) and 0 in EtOH at room temperature has been... 

Photocatalytic decomposition of alcohol Electro-oxidation of hydrogen Electroreduction of oxygen Ammonia synthesis Carbon monoxide methanation Carbon monoxide methanation Carbon monoxide oxidation Propene hydrogenation Benzene hydrogenation Oxidation of ethylene Coal liquefaction Electroreduction of oxygen Dehydrogenation of butadiene... 

Lithium iodide oxygen Dehydrogenation at high temp. 

The last example is an interesting application of the diene synthesis, for the adduct upon dehydrogenation (most simply by the action of oxygen upon its solution in alcoholic potash) yields 2 3-dimethylantbraquinone. 

Some isopentane is dehydrogenated to isoamylene and converted, by processes analogous to those which produce methyl /-butyl ether [1634-04-4] (MTBE) to /-amyl methyl ether [994-05-8] (TAME), which is used as a fuel octane enhancer like MTBE. The amount of TAME which the market can absorb depends mostly on its price relative to MTBE, ethyl /-butyl ether [637-92-3] (ETBE), and ethanol, the other important oxygenated fuel additives. 

Phenol Vi Cyclohexene. In 1989 Mitsui Petrochemicals developed a process in which phenol was produced from cyclohexene. In this process, benzene is partially hydrogenated to cyclohexene in the presence of water and a mthenium-containing catalyst. The cyclohexene then reacts with water to form cyclohexanol or oxygen to form cyclohexanone. The cyclohexanol or cyclohexanone is then dehydrogenated to phenol. No phenol plants have been built employing this process. 

Styrene undergoes many reactions of an unsaturated compound, such as addition, and of an aromatic compound, such as substitution (2,8). It reacts with various oxidising agents to form styrene oxide, ben2aldehyde, benzoic acid, and other oxygenated compounds. It reacts with benzene on an acidic catalyst to form diphenylethane. Further dehydrogenation of styrene to phenylacetylene is unfavorable even at the high temperature of 600°C, but a concentration of about 50 ppm of phenylacetylene is usually seen in the commercial styrene product. 

Dehydrogenation, Ammoxidation, and Other Heterogeneous Catalysts. Cerium has minor uses in other commercial catalysts (41) where the element s role is probably related to Ce(III)/Ce(IV) chemistry. Styrene is made from ethylbenzene by an alkah-promoted iron oxide-based catalyst. The addition of a few percent of cerium oxide improves this catalyst s activity for styrene formation presumably because of a beneficial interaction between the Fe(II)/Fe(III) and Ce(III)/Ce(IV) redox couples. The ammoxidation of propjiene to produce acrylonitrile is carried out over catalyticaHy active complex molybdates. Cerium, a component of several patented compositions (42), functions as an oxygen and electron transfer through its redox couple. 

The metal obtained by this process contains less iron and oxygen than that from the chrome alum electrolyte. The gas content is 0.02 wt % O, 0.0025 wt % N, and 0.009 wt % H. If desired, the hydrogen content can be lowered still further by a dehydrogenation treatment. 

There are two ways to produce acetaldehyde from ethanol oxidation and dehydrogenation. Oxidation of ethanol to acetaldehyde is carried out ia the vapor phase over a silver or copper catalyst (305). Conversion is slightly over 80% per pass at reaction temperatures of 450—500°C with air as an oxidant. Chloroplatinic acid selectively cataly2es the Uquid-phase oxidation of ethanol to acetaldehyde giving yields exceeding 95%. The reaction takes place ia the absence of free oxygen at 80°C and at atmospheric pressure (306). The kinetics of the vapor and Uquid-phase oxidation of ethanol have been described ia the Uterature (307,308). 

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