Hydrocarbons, photochemically driven

The above reactions proceed via free radical coupling. An alternative system for photochemically driven hydrocarbon functionalization evidently proceeds via the carbanion, which is obtained from reduction of the initially formed free radical3. The carbanion reacts with acetonitrile to give, after in situ hydrolysis, the methyl ketone, e.g., formation of (tricyclo[3.3.1.13-7]dec-1-yl)ethanone6. 

A photochemically driven reaction that mimics biological photosynthesis, electron-transfer, and hydrocarbon-oxidation reactions is described. The reaction occurs at room temperature and uses 2 as the ultimate oxidant. Most importantly, the reaction can be run for hours without significant degradation. This means that the oxidation of low molecular weight alkanes by O2, which proceeds at a lower rate than for hexane, can be investigated. Further studies are underway to determine the detailed reaction mechanisms involved in the photochemical reaction and the relative contributions of various oxidative pathways. Transient absorption and Raman spectrocopic techniques will also be applied to determine reaction rates. 

In addition to these principal commercial uses of molybdenum catalysts, there is great research interest in molybdenum oxides, often supported on siHca, ie, MoO —Si02, as partial oxidation catalysts for such processes as methane-to-methanol or methane-to-formaldehyde (80). Both O2 and N2O have been used as oxidants, and photochemical activation of the MoO catalyst has been reported (81). The research is driven by the increased use of natural gas as a feedstock for Hquid fuels and chemicals (82). Various heteropolymolybdates (83), MoO.-containing ultrastable Y-zeoHtes (84), and certain mixed metal molybdates, eg, MnMoO Ee2(MoO)2, photoactivated CuMoO, and ZnMoO, have also been studied as partial oxidation catalysts for methane conversion to methanol or formaldehyde (80) and for the oxidation of C-4-hydrocarbons to maleic anhydride (85). Heteropolymolybdates have also been shown to effect ethylene (qv) conversion to acetaldehyde (qv) in a possible replacement for the Wacker process. 

Well, the ozone concentration in the absence of the local smog tribution, it is my strong feeling that at that level the ozone is not produced in the stratosphere but is of chemical origin, driven primarily by the natural hydrocarbon oxidation cycles, as Chameides talked about yesterday. The large increase on that of course is the photochemical contribution, and there are a lot of mechanisms involved in that production term. So I do not know how far you want to dive into this question at this time. The ozone that you find in the upper troposphere may in isolated cases come directly from the strato-... 

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