products were almost unity over freshly prepared Raney Ni but the axial Me counterparts were favoured over aged catalyst. The axial Me products were also preferred on Pt or Rh catalysts. Pd catalysed hydrogenation gave predominantly the equatorial Me isomers at high catalyst ratio, while the axial Me counterparts were favoured at the early stage of the reaction at a catalyst-substrate ratio of 1:20. The change
在几种过渡
金属催化剂上将取代的烷基
亚甲基环己烷氢化。表观异构产物的比例与新鲜制备的阮内
镍几乎一致,但轴向Me对应物优于陈化催化剂。轴向Me产物在Pt或Rh催化剂上也是优选的。Pd催化的氢化反应在高催化剂比例下主要生成赤道Me异构体,而轴向Me异构体则在反应初期以催化剂与底物的比例为1:20受到青睐。取决于催化剂的量,差向异构产物的比率的变化是由于在高催化剂比率下,环外双键快速迁移至
环己烷环内部的缘故。根据改良的Horiuti-Polanyi机理讨论了氢化机理。