Cyclopentene, di-t-butylacetylene, 3-hexyne, cis- and trans-di-t-butylethylene, bicyclo[2,2,1] heptene, and bicyclo[2,2,2]octene were hydrogenated with H2 and with D2 in a liquid-phase, batch reactor at 20 °C on Pd SiO2and Pt SiO2. The effect of the presence of unsaturated hydrocarbon on the reaction, H2 + D2 → 2HD, was also investigated. In hydrogenation of the acetylenes, trans-ene and alkane were formed via α,α,β-triadsorbed alkane and this path was promoted by relief of intraadsorbate strain in the adsorbed acetylene during hydrogenation of di-t-butylacetylene. Hydrogenations of the cis- and trans-di-t-butylethylene proceeded by different mechanisms because of intraadsorbate strain in the adsorbed cis-ene. The ratio of isomerization to hydrogenation in the reaction of the cis-olefin with H2 was very much larger than usual because of the large adsorbate-surface strain in the adsorbed trans-ene. Adsorbed hydrogen was in preequilibrium on neither catalyst and adsorbed olefin was not in preequilibrium on Pt SiO2 and probably not on Pd SiO2 except perhaps for trans-di-t-butylethylene. The effect of the two kinds of steric strain on rates of hydrogenation is analyzed.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry