Dehydrogenation oxygen

Lanza, D. L. Yost, G. S. Selective dehydrogenation/oxygenation of 3-methylindole by cytochrome P450 enzymes. Drug Metab. Dispos. 2001, 29, 950-953. 

Figure 4 Variations on an oxidative theme the dehydrogenation/oxygenation connection. C-12-initiated oxidation catalyzed by oleate desaturase and its homolog oleate 12-hydroxylase (a) and acetylenase and its homolog epoxidase (b).

M0O3 possesses "structural specificities" in oxidation reaetions and related processes carried out in the presence of oxygen (oxidative dehydrogenation, oxygen-assisted dehydration... 

Valuable chemicals can principally be produced from paraffins if these unreactive compounds can be functionalized. This primarily requires the activation of the rather unreactive paraffinic C-H bond or C-C bond. Therefore, high temperatures are usually applied in the functionalization of paraffins. An interesting route is the partial oxidation of these compounds. This may yield olefins by oxidative dehydrogenation, oxygenates by oxygen insertion, or even nitrile compounds if a reactive nitrogen compound is added to the feed. 

Dehydrogenation, oxygen introduction, and destnu on of carbon linkages may all occur in the same process of oxidation, e.g., in the oxidation of naphthalene to phthalic anhydride ... 

The cyclization of three or more molecules of cadaverine yields the formation of tetracyclic alkaloids (e.g., lupanine and sparteine). These cyclic alkaloids are then transformed by cellular enzymes through dehydrogenation, oxygenation, hydrox-ylation, glycosydation, or esterification to yield a variety of alkaloids [20-23]. 

Key words Catalytic oxidation, homogeneous catalysis, dioxygen activation, dioxygen conplexes, biomimetic oxidation, functional metaUoenzyme models, oxidation mechanisms, oxidative dehydrogenation, oxygen insertion, aUcene epoxidation, catecholase reaction... 

The conversion of alkanes in presence of oxygen comprises of dehydrogenation, oxygenation, and combustion reactions. The product distribution depends on the nature of the catalyst, the nature of the alkane [3], and the operating conditions. Invariably it is noticed that with an increasing alkane conversion the selectivity to carbon oxides increases at the expense of the selectivity to alkenes. 

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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