Carbon monoxide reaction with oxygen atoms

Electronic excitation from atom-transfer reactions appears to be relatively uncommon, with most such reactions producing chemiluminescence from vibrationaHy excited ground states (188—191). Examples include reactions of oxygen atoms with carbon disulfide (190), acetylene (191), or methylene (190), all of which produce emission from vibrationaHy excited carbon monoxide. When such reactions are carried out at very low pressure (13 mPa (lO " torr)), energy transfer is diminished, as with molecular beam experiments, so that the distribution of vibrational and rotational energies in the products can be discerned (189). Laser emission at 5 p.m has been obtained from the reaction of methylene and oxygen initiated by flash photolysis of a mixture of SO2, 2 2 6 (1 )-... 

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. 

Of these reactions in which CO coordinates with the oxidized form of metals, the most important is the reaction with the iron atom in the hemoglobin of the blood, leading to carbon monoxide poisoning. This iron atom is part of a ring structure similar to that in chlorophyll (Chap. 6), and it ordinarily takes part in the metabolic process by reversibly forming a Fe—0—0— compound with the oxygen of the air. If carbon monoxide... 

Reaction of Carbon Monoxide with Oxygen Atoms from the Thermal Decomposition of Ozone... 

The reaction of oxygen atoms with carbon monoxide is an important reaction in many combustion systems. Although there is an extensive literature on this reaction Q) there is disagreement and uncertainty on the molecularity of the reaction, on the kinetic parameters and on the mechanism of the chemiluminescence. We have investigated this reaction using 0-atoms from the thermal decomposition of ozone. This has advantages compared to systems where... 

The adsorbed oxygen atom on the copper surface is removed by reaction with carbon monoxide and provides a pathway for the formation of the carbon dioxide needed in the main reaction. 

An alternative surface reaction which has been suggested is a reaction between an adsorbed oxygen atom with an adsorbed carbon monoxide molecule to form carbon dioxide which is immediately desorbed. The reaction rate is again given by the equation above. 

Even if it is assumed that the reaction is ionic, Occam s Razor would lead to the conclusion that the system is too complex and that the effort to keep it ionic is too great. It is difficult to undersand why step 8c is slow and why a simple uncharged complex would not be equally reasonable. We prefer a mechanism in which the carbon monoxide molecule is adsorbed parallel to the surface and in which the oxygen orbitals as well as the carbon orbitals of C=0 bond electrons interact with the metal. It seems reasonable that hydrogenolysis occurs exclusively only because the oxygen is held in some way while the two bonds are broken and it finally desorbs as water. The most attractive picture would be (a) adsorption of CO and H2 with both atoms on the surface... 

Carbon monoxide seriously impedes transport of oxygen. The deadly effect of inhaled CO results from its reaction with hemoglobin. A CO molecule is almost the same size and shape as O2, so it fits into the binding pocket of the hemoglobin molecule. In addition, the carbon atom of CO forms a stronger bond to than does O2. Under... 

The chemical reactivity of cobalt cluster anions, Co (n = 2-8), toward 02, N2, and CO have been investigated using a flow tube reactor (226). The reactivity was found to be in the order 02 > CO > N2 the least reactive ligand N2 only reacted with C07 and Cog. The primary reaction of oxygen was the removal of one or two cobalt atoms from the cluster. Carbon monoxide reacts by multiple additions giving saturation limits shown in Table V. 

Exposure of the clean stepped platinum surface to oxygen caused saturation of the step and kink sites (no adsorption occurred on a 111 surface under identical conditions). The oxygen atom-saturated surface was then exposed to varying amounts of carbon monoxide. Both carbide carbon and CO carbon C Is peaks formed, with a one-to-one correspondence between the growth of carbide and the decrease of surface oxygen atoms. These data are consistent with threee possible reaction schemes ... 

The first scheme was ruled out by showing that, at room temperature, a surface formed by very brief exposure of the oxygen-saturated surface to carbon monoxide is stable after removal of the carbon monoxide from the reaction chamber. In other words, no further surface carbide formed by lateral reactions of adsorbed carbon monoxide with surface oxygen atoms. The second scheme was ruled out by showing that exposure of the surface formed in the latter experiment to oxygen had no effect. Consequently the third scheme is believed to represent the mechanism of oxidation of carbon monoxide at the step and kink sites of platinum. 

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