HOMOGENOUS AND HETEROGENOUS CATALYTIC-HYDROGENATION AND ISOMERIZATIONOF HEX-1-ENE BY PALLADIUM(II) SCHIFF-BASE COMPLEXES

Pd-II complexes of Schiff bases with N2O2 donor sets were tested for t heir catalytic activity towards the reductive hydrogenation of hex-1-e ne. During the hydrogenation, trans- and cis-hex-2-ene isomers were fo rmed which generally react more slowly than hex-1-ene, hence the rate of hydrogenation tends to slow down with increasing conversion. The ra tes 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 H-2 and the polarity of reaction medium pl ay a significant role in the hydrogenation yield and selectivity. Hydr ogenation and isomerization are parallel reactions; a mechanism for th e isomerization is proposed.