Hydrophobic organotin fragments, grafted to the surface of a rhodium particle can strongly modify the rate of the hydrogenation of internal or terminal carbon-carbon (C-C) double bonds of unsaturated primary alcohols. In this work, the rate of hydrogenation of trans-2-hexenol and 5-hexenol was determined at room temperature under 20 bar of hydrogen in butanol + water (30 + 10) solution for Rh/SiO2 catalysts which were either used unmodified or modified with Sn(n-C4H9)4. It was found that the presence of alkyl groups decreases the ratio between the rate of hydrogenation of the terminal and internal double bond by a factor of 4. These results are explained by the formation of a hydrophobic layer around the modified particle which inhibits the adsorption of the unsaturated alcohol by its internal double bond.
- Rhodium-tin catalysts
- Selective hydrogenation of unsaturated alcohols
- Surface organometallic chemistry on metals
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