Hydrocarbons by metals

Effect of strong acids. The rates of oxidation of aromatic hydrocarbons by metal acetate oxidants are also dramatically enhanced in the presence of strong acids. It has recently been reported275 that Mn(III) and Co(III) acetates in the presence of strong acid activators, such as trichloroacetic or trifluoroacetic acid (TFA), rapidly and selectively oxidize aromatic side chains at 25°C. 

Primary and secondary halides can be reduced to hydrocarbons by metal hydrides. Tin hydride, (n-Bu)3SnH cleaves some C-X bonds. 

This initiation step may occur in a number of ways by thermal decomposition of hydrocarbons with weak C-H bonds, by oxidation of hydrocarbons by metal ions via free radical routes, by reaction with oxygen gas, etc. 

S. Chatterjee H. L. Greene. Oxidative catalysis of chlorinated hydrocarbons by metal-loaded acid catalysts. Journal of Catalysis, 130 76-85,1991. 

The R—H bond rupture followed by the formation of the metal-alkyl bond Pt—R is the rate-determining step in the activation of saturated hydrocarbons by metal complexes. The exchange rate decreases with the increase of branching in the hydrocarbon molecules. The scheme in equation 188 illustrates the simultaneous formation of organic chlorides and unsaturated hydrocarbons besides the deuteriation of saturated hydrocarbons (methane, ethane, propane, n-butane, i-butane, n-hexane, c-hexane, toluene in 0.1-0.7M water solutions of H2PtCl6, containing 5%K2PtCl4 at 120 °C in sealed ampoules . ... 

A number of reviews with relevant material address K-complexes of various kinds and iiKlude reviews on the syntheses of cationic 7t-complexes of the transition metals, die activation of C-C bonds in unsaturated hydrocarbons by metal complexes, a review on phosphorus heterocycles and phosphorus analogues of unsaturated hydrocarbon transition metal n-omiplexes J metal-complex catalyzed polymerizations of a-alkenes, coordination equilibria and coupling leactitms of unsaturated hydrocarbons at a metal centre, oligomerization of a-alkenes to higher oligomers, an annual survey on the chemistry of selected n-complexes for the year 1989, an annual survey on the chemistry of ferrocene for the year 1989, and in a number of articles in a journal issue devoted to alkene metathesis. 

Table 2. Monooxygenalions of hydrocarbons by metal complexes with molecular oxygen...

Sharpe RG, Dixon warren S, Durston PJ, Palmer RE (1995) The electronic cattilyst dissociation of chlorinated hydrocarbons by metal-insulator-metal electron emitters. Chem Phys Lett 234 354-358... 

A review on the industrial applications of homogeneous catalysts is particularly welcome. The proceedings of recent symposia and a general text have been published in addition to reviews on metal cluster catalysts, activation of saturated hydrocarbons by metal complexes in solution, catalysis by arene Group-VIB tricarbonyls, titanocene-catalysed reactions ofalkenes, transition-metal hydrides in catalysis, the mechanisms of the catalytic cyclization of aliphatic, hydrocarbons, asymmetric hydrosilylation and asymmetric synthesis. A n.m.r. study of the conformations of chelated Diop and a MO study of organo-metallic migration reactions are also of interest. Polymer supported catalysts have been reviewed and the relationship between cross-linking of the polymer and catalytic activity has been discussed. ... 

In general, the carbides of metals of Groups 4—6 (IVB—VIB) are prepared by reaction of elementary carbon or hydrocarbons and metals and metal compounds at high temperatures. The process may be carried out ia the presence of a protective gas, under vacuum, or ia the presence of an auxiUary metal (menstmum). 

The oxidation of hydrocarbons, including hydrocarbon polymers, takes the form of a free-radical chain reaction. As a result of mechanical shearing, exposure of ultraviolet radiation, attack by metal ions such as those of copper and manganese as well as other possible mechanisms, a hydrocarbon molecule breaks down into two radicals... 

Schimmel Co. attempted to acetylise the alcohol by means of acetic anhydride, but the reaction product only showed 5 per cent, of ester, which was not submitted to further examination. The bulk of the alcohol had been converted into a hydrocarbon, with loss of water. Ninety per cent, formic acid is most suitable for splitting off water. Gne hundred grams of the sesquiterpene alcohol were heated to boiling-point with three times the quantity of formic acid, well shaken, and, after cooling, mixed with water. The layer of oil removed from the liquid was freed fi-om resinous impurities by steam-distillation, and then fractionated at atmo.spheric pressure. It was then found to consist of a mixture of dextro-rotatory and laevo-rotatory hydrocarbons. By repeated fractional distillation, partly in vacuo, partly at ordinary pressure, it was possible to separate two isomeric sesquiterpenes, which, after treatment with aqueous alkali, and distillation over metallic sodium, showed the following physical constants —... 

The photo-Kolbe reaction is the decarboxylation of carboxylic acids at tow voltage under irradiation at semiconductor anodes (TiO ), that are partially doped with metals, e.g. platinum [343, 344]. On semiconductor powders the dominant product is a hydrocarbon by substitution of the carboxylate group for hydrogen (Eq. 41), whereas on an n-TiOj single crystal in the oxidation of acetic acid the formation of ethane besides methane could be observed [345, 346]. Dependent on the kind of semiconductor, the adsorbed metal, and the pH of the solution the extent of alkyl coupling versus reduction to the hydrocarbon can be controlled to some extent [346]. The intermediacy of alkyl radicals has been demonstrated by ESR-spectroscopy [347], that of the alkyl anion by deuterium incorporation [344]. With vicinal diacids the mono- or bisdecarboxylation can be controlled by the light flux [348]. Adipic acid yielded butane [349] with levulinic acid the products of decarboxylation, methyl ethyl-... 

The role of catalytic metal oxide is not only to etrhance the step from S to S, but also, mote importantly, to enhance the step from S to S, which evidently is relatively slow. To achieve this requires a massive supply of active hydrogen ftom hydrocarbons by virtue of interactions with the catalyst. This can be represented by combining the first three equations above as follows ... 

Small-particle-size cement has found a number of uses in production and injection well casing repair jobs [440]. Oil-based cement is particularly useful for water shutoff jobs, because the hydrocarbon slurry sets only in the presence of water, so the oil-producing sections of a reservoir remain relatively damage free after water shutoff. The selective water shutoff with oil-based cement also has been used with polymers crosslinked by metal crosslinkers [442,1178]. 

When the temperature of a carbonate reservoir that is saturated with high-viscosity oil and water increases to 200° C or more, chemical reactions occur in the formation, resulting in the formation of considerable amounts of CO2. The generation of CO2 during thermal stimulation of a carbonate reservoir results from the dealkylation of aromatic hydrocarbons in the presence of water vapor, catalytic conversion of hydrocarbons by water vapor, and oxidation of organic materials. Clay material and metals of variable valence (e.g., nickel, cobalt, iron) in the carbonate rock can serve as the catalyst. An optimal amount of CO2 exists for which maximal oil recovery is achieved [1538]. The performance of a steamflooding process can be improved by the addition of CO2 or methane [1216]. 

Retard efficiently oxidation of polymers catalysed by metal impurities. Function by chelation. Effective metal deactivators are complexing agents which have the ability to co-ordinate the vacant orbitals of transition metal ions to their maximum co-ordination number and thus inhibit co-ordination of hydroperoxides to metal ions. Main use of stabilisation against metal-catalysed oxidation is in wire and cable applications where hydrocarbon materials are in contact with metallic compounds, e.g. copper. 

Examples of the need for multimedia models are found in contemporary problem areas. Polynuclear aromatic hydrocarbons and metals are emitted into the atmosphere as trace impurities with the products of coal combustion. The organics have low vapor pressure and partially condense on emitted particulates in a stack plume. The particulates are transferred to the soil by dry deposition, rainout or washout. The metals manifest... 

The aluminium-solvent slurry produced by metal atom/solvent co-condensation at — 196°C is so reactive that oxygen is abstracted from the solvent ether as the mixture is allowed to melt. Hydrocarbon solvents are more suitable (but halocarbon solvents would react explosively). 

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