Study On The Hydrogenation Of Imines Catalyzed By Nanoporous Gold

Nanoporous gold is a kind of new catalyst, which is first reported by M. Baumer in 2010. It has a nanoporous structure, the size of which ranges from 5 to 50nm, which lead to the high surface area ratio and stable frame. These advantages make it easy to reuse. Recently there are many literatures relating to nanoporous Au have been published. But most of them are oxidation reaction, for example, methnol oixidation with O2 catalyzed by nanoprous Au, monoxide oixidation with O2 catalyzed by nanoprous Au. There are also reduction reaction, for instance, nanoporous cold catalyst for highly selective semihydrogenation of alkynes.But there is no literature about nanoporous Au catalyzed hydrogen hydrogenation reported yet. Here we study on the hydrogenation of imines catalyzed by nanoporous Au. The result shows that nanoporous Au is an effective catalyst and imines can be selectively reduced. Besides, nanoporous Au shows much less leaching compared with Pd, Ni et al. The retest experiment shows that after reusing for many times, the activtity is barely decreased.In order to optimize the reaction condition, we seperately change the catalyst amout, solvents, temperature, reaction time and H2 pressure. Here is the best reaction condition: ethnol as solvent, temperature is 80℃, H2 is 10 bar, reaction time is 10 h, the catalyst amout is 5 mol%.We screened 15 different substrates, the yield ranges from 72% to 99%. The result shows that C=N bond can be selectively reduced when C=O, C=C, C-X bond exist. The reusing test shows that after reusing for many times, the activtity is barely decreased. ICP shows no leaching taking place during the reaciton.