Mercury photosensitized oxidation

Bell and McDowell16 have recently reviewed the basis for the mercury photosensitized oxidation of hydrocarbons. When mercury is illuminated by 2537 A. light, the excited mercury atom may be quenched by either oxygen or the hydrocarbon... 

Gray61 and Nalbandyan94 studied the mercury photosensitized oxidation of ethane in a flow system and showed that ethyl hydroperoxide was the chief initial product. Gray61 similarly obtained considerable amounts of methyl hydroperoxide in the photosensitized oxidation of methane. However, Watson and Darwent127 pointed out that the chain mechanism they proposed ... 

Turner et al.126 also favor reaction (176) to explain their results on the oxidation of ethyl radicals produced by the mercury photosensitized oxidation of ethylene. 

The mercury-photosensitized oxidation of CjF at 253.7 nm to give COFj can be explained by two processes [928,928a]. The first is attack of the CjF., by oxygen atoms resulting from the Hg-photosensitized decomposition of Oj ... 

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. 

Before mercury-photosensitized decomposition of nitrous oxide could be used as a technique for generation of oxygen atoms, it was necessary to establish unambiguously the primary step in this reaction. Early investigation (70) could not distinguish with certainty between the two possible primary steps... 

Fig. 21. Yield of oxime as a function of the nitric oxide concentration in the mercury-photosensitized decomposition of various propanes. O—C3H3 S—C3Da C —CH CD2CH3 -CDaCH-CIU...

Fig. 22. The yield of w-propyl radicals from the mercury-photosensitized decomposition of various propanes as a function of nitric oxide concentration. O—CjH8 ...

Bell and McDowell16 studied the Hg photosensitized oxidation of isobutane using a static system. There was a slow removal of mercury vapor ( = 6 X 10-4 at 30°C. and 2 X 10-4 at 100°C.). The main... 

The mercury photosensitized polymerization of acetylene has been studied by Steacie and LeRoy. They investigated the effect of nitric oxide on the reaction, and deduced that it proceeds at least partially by a free radical mecha ism. If this is so, the reaction must be... 

The photosensitized oxidations in solution for determination of ft by the slope-intercept method were carried out in a constant temperature bath with light from a 250-watt projector lamp with a UV-cutoff filter. Oxygen uptake was monitored with a conventional mercury burette. Polymer films also were irradiated with the same lamp containing a Coming CS 3-69 filter. 

To perform the dissociation of the hydrocarbon to alkyl radicals with C—C bond scission, a hydrocarbon molecule should absorb light with the wavelength 270-370 nm. However, alkanes do not absorb light with such wavelength. Therefore, photosensitizers are used for free radical initiation in hydrocarbons. Mercury vapor has been used as a sensitizer for the generation of free radicals in the oxidized hydrocarbon [206-212], Nalbandyan [212-214] was the first to study the photooxidation of methane, ethane, and propane using Hg vapor as photosensitizer. Hydroperoxide was isolated as the product of propane oxidation at room temperature. The quantum yield of hydroperoxide was found to be >2, that is, oxidation occurs with short chains. The following scheme of propane photoxidation was proposed [117] ... 

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