An-Najah Staff

A new class of supported carbonyl manganese catalyst was prepared by treating the dimeric decacarbonyldimanganese(0), Mn₂(CO)₁₀, with insoluble aminated poly(siloxane) surface. Solid state FT-IR spectra indicated that the supported catalyst is a dimeric complex that is substituted with two amine ligands, one at each Mn atom. The supported manganese complex was investigated as catalyst for the hydrosilylation reaction of terminal olefins. Contrary to the homogeneous Mn₂(CO)₁₀ catalytic system, the supported manganese complex was completely selective toward the hydrosilylation reaction with no detectable olefin isomerization or other side-reaction products. Furthermore, the catalyst was selective to produce the linear hydrosilylation product rather than the branched one. No lowering in catalyst activity due to the support was observed. A good proportion of the catalyst activity after separation and reuse was retained for at least four times. Highly reproducible catalytic activity measurements were obtained with catalytic samples taken from same prepared batch. Different prepared batches showed lower reproducibility. The effect of different reaction parameters, such as the solvent effect, the temperature effect, the concentration effect and the added-ligand effect have also been studied. Laine's kinetic studies indicated that the cluster remained intact during the reaction.

A new class of supported carbonyl manganese catalyst was prepared by treating the dimeric decacarbonyldimanganese(0), Mn2(CO)10, with insoluble aminated poly(siloxane) surface. Solid state FT-IR spectra indicated that the supported catalyst is a dimeric complex that is substituted with two amine ligands, one at each Mn atom. The supported manganese complex was investigated as catalyst for the hydrosilylation reaction of terminal olefins. Contrary to the homogeneous Mn2(CO)10 catalytic system, the supported manganese complex was completely selective toward the hydrosilylation reaction with no detectable olefin isomerization or other side-reaction products. Furthermore, the catalyst was selective to produce the linear hydrosilylation product rather than the branched one. No lowering in catalyst activity due to the support was observed. A good proportion of the catalyst activity after separation and reuse was retained for at least four times. Highly reproducible catalytic activity measurements were obtained with catalytic samples taken from same prepared batch. Different prepared batches showed lower reproducibility. The effect of different reaction parameters, such as the solvent effect, the temperature effect, the concentration effect and the added-ligand effect have also been studied. Laine's kinetic studies indicated that the cluster remained intact during the reaction.

The kinetics of oxidation of 1-octene and heptanal by 18-crown-6-ether-solubilized KMnO_4 in benzene and CH_2Cl_2 have been investigated. In benzene, the oxidation of 1-octene is first order with respect to the oxidant and zero order with respect to the substrate, whereas in CH_2Cl_2 the reaction is first order with respect to both substrate and oxidant. The reaction of heptanal followed different kinetics being first order with respect to both substrate and oxidant, regardless of whether benzene or CH_2Cl_2 was employed as the solvent. The values of activation energy E_a, standard enthalpy H^*, standard entropy change S^*, and standard free energy G^*, for the reaction, are reported. Mechanistic pathways for the studied reactions are also proposed.