Homogenous and heterogenous catalytic hydrogenation and isomerization of hex-1-ene by palladium(II) Schiff base complexes

Summary Pd^II complexes of Schiff bases with N₂O₂ donor sets were tested for their catalytic activity towards the reductive hydrogenation of hex-1-ene. During the hydrogenation, trans- and cis-hex-2-ene isomers were formed which generally react more slowly than hex-1-ene, hence the rate of hydrogenation tends to slow down with increasing conversion. The rates of hydrogenation and isomerization were studied in relation to the catalyst structure, time, type of catalysis and amount and nature of solvents. The solubility of H₂ and the polarity of reaction medium play a significant role in the hydrogenation yield and selectivity. Hydrogenation and isomerization are parallel reactions; a mechanism for the isomerization is proposed.