Ethylene-carbon monoxide effects

Effect of other factors on cellulose. Dry distillation at a temperature above 150°C causes cellulose to produce compounds of low molecular weight, such as water, methane, ethylene, carbon monoxide, carbon dioxide, acetic acid, and acetone. According to Pictet [49] dry distillation under reduced pressure yields a substance having the empirical formula C6H10Oj, laevo-glucosan which probably is /3-D-glucopyranose anhydride ... 

Palladium-based catalysts for ethylene/carbon monoxide copolymerisation are very effective high rates with conversions of more than 1 x 106 mol of ethylene and carbon monoxide per Pd active site were obtained [481],... 

Heck-type step-growth condensation polymerisation involves mainly palladium-based catalysts, although nickel-based catalysts are also effective. It is worth noting that this polycondensation requires a change in the oxidation state of the metal (e.g. Pd) [schemes (30) and (31)] [71], which is in contrast to chain growth polymerisation, such as ethylene/carbon monoxide alternating copolymerisation promoted by Pd-based catalysts [schemes (82) and (83) in Chapter 3], for which the preservation of the oxidation state of palladium, Pd(II), is typical [83-85] ... 

Whether or not CO can affect an increase in the oxidation rate of NO in the presence of hydrocarbons depends on the relative rates of these competing reactions. For a highly reactive hydrocarbon such as mesity-lene, the reaction of the hydrocarbon with hydroxyl radicals is so fast that the reaction of CO with OH cannot compete even at high CO-hydrocarbon ratios. For less reactive hydrocarbons such as ethylene and 1-butene, CO competes with the hydrocarbon for the OH radicals and, in systems containing these hydrocarbons, a carbon monoxide effect is possible. The rate constant for the reaction of ethylene with hydroxyl radicals has been measured to be 3.6 X 10 1/mole-sec 15). This is forty times greater than the rate constant of 8.9 X 10 1/mole-sec (JO) for the reaction of OH with CO. Therefore, a CO effect should be possible at CO-ethylene ratios of 40 or greater. Experimentally, an increase in the NO oxidation rate for this system was observed at a CO—hydrocarbon ratio of 50. 

Nakatsuka, S. and Andiady, A. (1994) Studies on enhanced degradable plastics. III. The effect of weathering of polyethylene and (ethylene-carbon monoxide) copolymers on moisture and carbon dioxide permeability. Journal... 

Faraday, who gives a long abstract, says I cannot form a distinct idea of the power to which he refers the phenomena . Faraday also brings in Dalton s idea (see Vol. Ill, p. 766) that one gas is a vacuum towards another gas , and his speculations are far from clear. He does not explain why the effects are specific to platinum and why other solids do not behave in the same way. He found that it is essential that the platinum shall be clean and found that ethylene, carbon monoxide, carbon disulphide and ether vapours, retard the combination of hydrogen and oxygen on platinum, but the metal acts when put into a pure gas mixture. Sulphuretted hydrogen and phosphoretted hydrogen, however, permanently inactivated the platinum unless treated with hot concentrated sulphuric acid or fused caustic potash and washed with water. 

From the results of other authors should be mentioned the observation of a similar effect, e.g. in the oxidation of olefins on nickel oxide (118), where the retardation of the reaction of 1-butene by cis-2-butene was greater than the effect of 1-butene on the reaction of m-2-butene the ratio of the adsorption coefficients Kcia h/Kwas 1.45. In a study on hydrogenation over C03O4 it was reported (109) that the reactivities of ethylene and propylene were nearly the same (1.17 in favor of propylene), when measured separately, whereas the ratio of adsorption coefficients was 8.4 in favor of ethylene. This led in the competitive arrangement to preferential hydrogenation of ethylene. A similar phenomenon occurs in the catalytic reduction of nitric oxide and sulfur dioxide by carbon monoxide (120a). 

Palladium(II) complexes possessing bidentate ligands are known to efficiently catalyze the copolymerization of olefins with carbon monoxide to form polyketones.594-596 Sulfur dioxide is an attractive monomer for catalytic copolymerizations with olefins since S02, like CO, is known to undergo facile insertion reactions into a variety of transition metal-alkyl bonds. Indeed, Drent has patented alternating copolymerization of ethylene with S02 using various palladium(II) complexes.597 In 1998, Sen and coworkers also reported that [(dppp)PdMe(NCMe)]BF4 was an effective catalyst for the copolymerization of S02 with ethylene, propylene, and cyclopentene.598 There is a report of the insertion reactions of S02 into PdII-methyl bonds and the attempted spectroscopic detection of the copolymerization of ethylene and S02.599... 

The kinetics and mechanism for oxygen transfer between 4-cyano-V,V,-dimethylaniline V-oxide and a C2-capped mexo-tetraphenylporphyrinatoiron(III) and mc5 o-tetrakis(pentafiuorophenyl)-porphyrinatoiron(III) have been established. Addition of a copper(II) porphyrin cap to an iron(II)-porphyrin complex has the expected effect of reducing both the affinities and rate constants for addition of dioxygen or carbon monoxide. These systems were studied for tetradecyl-substituted derivatives solubilized by surfactants such as poly(ethylene oxide) octaphenyl ether. ... 

The deoxygenation of tetrahydrofuran (THE, 90), which yields ethylene and carbon monoxide, is an interesting case. While this and other deoxygenations might be expected to proceed through an yild intermediate and a biradical as shown in Eq. 50, calculations (MP2/6-31G ) indicate that neither ylid 91 nor biradical 92 is an intermediate in this reaction. These calculations reveal a concerted removal of oxygen that proceeds to carbon monoxide and two molecules of ethylene without barrier. Experimental evidence that 91 is not an intermediate is provided by the fact that reaction of carbon with a mixture of 90 and 90-d generates ethylene and ethyl-ene-t/g in a 2.7 1 ratio.This secondary isotope effect of 1.13 (per D) would not be expected if 91 (or 92) were an intermediate. 

A systematic attempt to correlate the catalytic effect of different surfaces with their adsorptive capacity was made by Taylor and his collaborators. Taylor and Burns, for example, investigated the adsorption of hydrogen, carbon dioxide, and ethylene by the six metals nickel, cobalt, palladium, platinum, iron, and copper. All these metals are able to catalyse the hydrogenation of ethylene to ethane, while nickel, cobalt, and palladium also catalyse the reduction of carbon monoxide and of carbon dioxide to methane. 

Compensation effects have been reported for the oxidation of ethylene on Pd-Ru and on Pd-Ag alloys (207, 254, 255) discussion of the activity patterns for these catalysts includes consideration of the influence of hydrogen dissolved in the metal on the occupancy of energy bands. Arrhenius parameters reported (208) for ethylene oxidation on Pd-Au alloys were an appreciable distance from the line calculated for oxidation reactions on palladium and platinum metals (Table III, H). Oxidation of carbon monoxide on Pd-Au alloys also exhibits a compensation effect (256). 

In the case of ethylene itself the cyclopentene technique is obviously inapplicable and the relative rate constants have in this case been obtained in other ways, for example, by measuring yield of carbon monoxide formed by fragmentation of the products of reaction of oxygen atoms with ethylene. In this case the total pressure has to be kept approximately constant although some variation is not too important in view of the relatively small effect of pressure on CO yield at pressures normally used. 

The stepwise electron reduction of C02, whether direct or indirect, catalyzed, or by direct transfer on an apparently inert conductive surface, has been the object of considerable attention since the first concise reports of formate anion production. Since then, the list of possible derivatives has grown from formates to carbon monoxide, methane, ethylene, and short-chain saturated hydrocarbons. As noted in Section 12.1, this area of research has been expanded in recent years [8, 80, 83], with information relating to increased yields, to the effect of electrode materials on selectivity, as well as further speculations on possible reaction mechanisms, having been obtained on a continuous basis. Yet, the key to these synthetic processes-an understanding of the relationship between the surface of the electrode and the synthetic behavior of the system-seems no closer to being identified. 

The Rh(lll) surface was covered with carbon by decomposing 5 x 10 7 torr of either acetylene or ethylene at 1100 K for 10 minutes and subsequent flashing to 1200 K (230. Pre-adsorbed carbon had a very strong inhibiting effect on carbon monoxide chemisorption. This is the same effect it had on the methanation rate (36). The low inelastic scattering intensity indicated relatively small CO coverages while the broad elastic peak and... 

For large scale production of carbon nanotubes and nanofibers chemical vapor deposition (CVD) method is most effective. Acetylene, ethylene, propylene, methane, natural gas (consisting predominantly of propane), carbon monoxide were used as a source of carbon [ 1 -8] (in view of large number of publications on CNT synthesis these references are selected arbitrary). Ethylene and possibly propylene are most convenient carbon sources for mass synthesis of high quality multiwall CNT (MWNT). 

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