The Effects of SCILL Catalyst Modification on the Competitive Hydrogenation of 1-Octyne and 1,7-Octadiene versus 1-Octene

Competitive hydrogenation of mixtures of related unsaturated compounds remains a challenging problem. Recently, solid catalysts with an ionic liquid layer (SCILL) have shown potential for increased catalyst selectivity under batch conditions. Our results for the continuous flow competitive hydrogenation of 1-octyne and 1,7-octadiene versus 1-octene with a nickel SCILL catalyst indicate improved catalyst selectivity under trickle bed conditions. Different ionic liquids ([MMIM][MeOSO ₃], [MMIM][OcOSO ₃], [MMIM][NTf ₂], [MePsec-Bu ₃ ][MeOSO ₃], and [Et ₃S][NTf ₂]; MMIM=1,3-dimethylimidazole and Tf=trifluoromethanesulfonyl) with varying catalyst loadings were investigated. The results highlight the importance of potential site-specific interactions by the ionic liquid. They also indicate the importance of the cation for these effects.