Isotopic exchange cyclopentane-deuterium

G. Isotopic Exchange between Deuterium and Cyclopentane and Hexane... 

To assess any differences in isotopic exchange of a kanes on microcrystalline and amorphous catalysts, we examined isotopic exchange between deuterium and two saturated hydrocarbons, cyclopentane and hexane. The range of reaction temperatures for cyclopentane was 175-275° and the molar ratio of deuterium to hydrocarbon was 5.6. Catalysts were activated at 400° first in helium and then, after runs on the amorphous catalyst, the catalyst was reactivated in hydrogen to make it microcrystalline. Two series of such runs were made. At 250°, reaction rates on the amorphous catalysts were as follows run 285, 0.40 mmoles per hour per gram of Cr203 run 296, 0.36. On the micro-crystalline catalyst, the exchange rates were, for run 288, 2.0 run 299, 1.1. These rates were computed by... 

That products of intermediate oxidation level can be detected in the photocatalytic reactions of hydrocarbons and fossil fuels is also consistent with a surface bound radical intermediate . Photocatalytic isotope exchange between cyclopentane and deuterium on bifunctional platinum/titanium dioxide catalysts indicates the importance of weakly adsorbed pentane at oxide sites. The platinum serves to attract free electrons, decreasing the efficiency of electron-hole recombination, and to regenerate the surface oxide after exchange. Much better control of the exchange is afforded with photoelectrochemical than thermal catalysis > ) As before, hydrocarbon oxidations can also be conducted at the gas-solid interface... 

Figure 6. Initial rates vs Pt contents of the Pt/TiC>2 specimens for liquid methanol (A) or 1-propanol. (B) dehydrogenation at 298 K cyclopentane-deuterium exchange in gas phase at 263 K (C) oxygen isotope heteroexchange at 298 K over non-preoxidized (D) or preoxidized (E) samples.

The photocatalytic isotopic exchange between cyclopentane and deuterium (CDIE) was carried out in a static fused silica photoreactor described in ref (23),... 

Photocatalytic cyclopentane-deuterium isotopic exchange (CDIE)... 

The isotopic exchange reaction between deuterium and (+)3-methyl-hexane on nickel and palladium catalysts at temperatures above 100° leads to racemization of the optically active hydrocarbon. In exchange between deuterium and cycloalkanes at temperatures between —50° and about 75°, a discontinuity separates the concentrations of C H D and. In cyclopentane at about 50°, for example, exchange... 

Multiple exchange proceeds most readily in the presence of P-C-H bonds, which can be explained by p-elimination leading to an olefin-hydrido complex either with a single metal atom or with the participation of a neighboring metal atom. The importance of intermediate complex formation with an olefin is confirmed by the absence of exchange via a quaternary carbon atom. Cyclopentane in the isotope exchange with molecular deuterium catalyzed by metals of... 

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