The influence of different monodentate P-ligand mixtures on Rh-catalyzed 1-butene hydroformylation

Four monodentate P-ligands and their mixtures(six groups of double-ligand systems,four groups of triple-ligand systems and one group of tetra-ligand system)were used with Rh(acac)(CO)_2(acac=acetylacetonate)or Rh(acac)CO(PPh_3)as the catalyst in the hydroformylation reaction of 1-butene.It was found that different Rh catalysts showed little difference in the catalysis performance.The general order of catalysis performance is doubleligand system N single-ligand system N triple-ligand system N tetra-ligand system.Some synergistic effect in the double-ligand system was detected which needs a further investigation.

Direct Synthesis of Ultrahigh Molecular Weight Functionalized Isotactic Polypropylene

Ultrahigh molecular weight functionalized isotactic polypropylene(f-UHMW-iPP)through the direct copolymerization of propylene with polar monomers is highly desirable but has not been accessed thus far because it involves challenging regio-and stereochemistry along with usually reduced molecular weight.Herein,in contrast to the unsuccessful catalyst strategy,a polar monomer-assisted strategy is used to access the above material.The introduction of O-or S-functionalized long-chain polar olefins into the hafnium-catalyzed copolymerization of propylene(and bulkierα-olefins)significantly increases the copolymer molecular weight with a maximum observed increase of+488%.f-UHMW-iPP and functionalized isotactic poly(α-olefin)s(M_(w)>2000 kDa,[mmmm]:99%)are thus prepared at ambient conditions.The incorporation of 1 mol%of polar monomer improves the surface property and significantly increases the long-sought toughness(860%)of brittle iPP,without reducing the tensile strength(42 MPa)due to the key achievement of ultrahigh molecular weight.A discussion of the mechanism involved in the beneficial effects of incorporating the polar monomer is herein presented by an in-depth density functional theory calculation.