REACTIONAL MECHANISM OF VARIOUS ISOMERIC C6 ALKENES OVER REDUCED MIXED CU-CE-AL OXIDE CATALYSTS

Hydrogenation and isomerization of many C6 alkenes are studied over re duced Cu-Ce-Al oxide catalysts. Activity and selectivity are strongly dependent on the steric and electronic effects characteristic of the r eagent molecule. The less crowded the double bond of the alkene, the m ore important the activity is. On the other hand, the more polar the r eagents are, the more favoured the hydrogenation selectivity is. The p roposed reaction mechanism can be considered as a balance between the passage by an intermediary sigma-alkyl leading mainly to hydrogenation product, and a concerted mechanism where the resultant is a double bo nd migration product. The equilibrium of this balance depends essentia lly on the polarity of the used reagent.