Atomic reaction with oxygen

Leger, L. Oxygen Atom Reaction with Space Shuttle Materials at Orbital Altitudes, NASA Technical Memorandum 58246, May 1982... 

First experiments on oxygen atom reactions with hydrocarbons, with the zone of discharge in water vapor, as well as in O2, used as a source of 0 atoms, have shown that the reaction products are formaldehyde, acetaldehyde, acids, alcohols, peroxides, i.e., products of lower degrees of conversion than that yielding H20, CO, and C02. 

Thus, CH20 and CO are obtained in equal amounts. Other reactions of a lower probability are the formation of alcohol by reaction 0 + C2H6 - C2H6OH, possibly depending on pressure, and the formation of acetaldehyde 0 + C2H6 - C2H 0 + H2. It will be noted that the formation of alcohol was observed by Murad and Noyes63 in the course of oxygen atom reactions with ethane. 

It follows that oxygen atom reactions with saturated and unsaturated hydrocarbons proceed with scission of the C—C and C=C bonds, respectively. 

Cvetanovic67 was concerned with oxygen atom reactions with unsaturated hydrocarbons. The oxygen atoms were obtained in his experiments by mercury-photosensitized decomposition of N20. Cvetanovi6 came to the conclusion that the reaction of oxygen atoms with ethylene proceeded essentially with scission of the hydrocarbon bond, while with higher olefins this was not observed. Corresponding oxides (epoxides) and carbonyl compounds were formed in the course of the reaction. 

Great attention was paid to oxygen atom reactions with acetaldehyde. It will be mentioned that the study of this reaction encountered greater difficulties. 

In investigating the oxygen atom reaction with carbon monoxide 1 62 it was found that this reaction at pressures of 2.5 mm. Hg and higher obeyed essentially a bimolecular law, although a slow trimolecular reaction might have occurred as well. 

Cvetanovi6,0>71 determined the relative rate constants of oxygen atom reactions with various molecules. 

Rate Constants for Oxygen-Atom Reactions with Various Molecules... 

An additional field where the NO2 technique offers particular advantages is in the study of oxygen atom reactions with olefins in the presence of molecular oxygen (90). This topic is outside the scope of the present article since it deals with secondary interactions. It is a most challenging field which is of great importance for the understanding of photochemical air pollution phenomena (67). 

In conclusion, it is evident that considerable progress has been made in the understanding of some of the fundamental features of oxygen atom reactions with olefins. A number of these features will no doubt prove to... 

L. J. Leger, Oxygen Atom Reactions with Shuttle MateriaJs at OrbitaJ Altitudes — Data amd ExperimentaJ Status, AIAA 21st Aerospace Sciences Meeting held in Reno, NV, 10-13 January 1983, (AIAA, New York, 1983) Paper No. 83-0073. 

It is clear that the oxygen atom reactions with simple hydrides can be used as models to understand the effect of electronic excitation on the kinetics and dynamics of the more complex oxygen atom - hydride reactions. The details of the latter, however, appear to be quite complicated. These are the subject of work in many laboratories at present, however, and novel and sophisticated experimental techniques are being used to elucidate the more subtle aspects of their dynamics. 

---