Olefins, hydrogenation isomerization reaction

Normally, the hydrogenation of a readily hydrogenated double bond occurs over palladium-on-charcoal in ethanol at room temperature and atmospheric pressure. The more difficultly reduced olefins require elevated reaction temperatures and/or pressures for the reaction to proceed at a reasonable rate. The saturation of an 8(14)-double bond is virtually impossible under normal hydrogenation conditions. In order to remove unsaturation at this position it is necessary to first isomerize the double bond to the readily hydrogenated 14 position by treatment with dry hydrogen chloride in chloro-form. ° ... 

The mechanism for hydrosilylation in Figs. 6 and 7 clearly has much in common with suggestions regarding homogeneous transition metal catalysis for other processes involving olefins, such as hydrogenation, isomerization, the oxo reaction, and oligo- and polymerization. 

Methanation and olefin hydrogenation or isomerization (secondary and side reactions)... 

The conjugated diene (including the trans-trans, trans-cis, and cis-cis isomers) can further add ethylene to form Cg olefins or even higher olefins (/). The mechanism of isomerization is proposed to be analogous to butene isomerization reactions (4, 8), i.e., 1-butene to 2-butene, which involves hydrogen shifts via the metal hydride mechanism. A plot of the rate of formation of 2,4-hexadiene vs. butadiene conversion is shown in Fig. 2. 

While Ru-dppes incorporated mesoporous silica was used in isomerization reactions [75], hydrogenation of various olefins was aeeomplished by the use of Rh-dppes complex... 

Hydrogenation and Isomerization Reactions of Olefinic Alcohols Catalyzed in... 

The overall reaction of olefins, hydrogen, and carbon monoxide can be complex since not only are both linear and branched aldehydes (and hence alcohols) formed, but the same catalysts promote olefin isomerization. The products formed may be summarized as follows ... 

If a catalytic cycle composed of several elementary processes is promoted on an isolated single site, we could make distinctions about the function of the active sites. For example, some metal complexes which are active for the isomerization reaction of olefins via alkyl intermediates are not effective catalysts for the hydrogenation reaction, and such differences in catalytic ability of the metal complexes is explained by the numbers of coordinatively unsaturated sites which are available for the reactions as described schematically in Scheme 7. 

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