No abstract

No abstract

Five-or seven-membered ring lactones are synthesized, in good selectivity and high yields, by the cyclocarbonylation reaction of 2-allylphenols, using a tridentate diphosphinoaryl ligand (PCP-type) palladium(II) catalyst immobilized on silica (A) and silica supported dendrimers (B, C and D). These immobilized catalysts, which are highly active and can be recycled by simple filtration in air, and reused with only moderate loss of activity, combine the advantages of heterogeneous and homogeneous catalysts. These complexes are also stable towards oxygen and moisture.

No abstract

Homogeneous catalytic hydroformylation of styrene-butadiene copolymers was examined with five rhodium catalyst precursors. Under a total pressure of 800 psi H2 and CO at 40°C, [Rh(COD)2]-BF4 and [Rh(COD)Cl]2 are more active than HRh(CO)(PPh3)3, [Rh(COD)dppb]BF4, or [Rh(COD)]BPh4. The hydride HRh(CO)(PPh3)3 is the most effective of the catalysts at 200 psi and 40°C. Full conversion of polyolefin could be achieved using [Rh(COD)2]BF4 or [Rh(COD)Cl]2 as the hydroformylation catalyst. The polyaldehydes, characterized using IR and 1 H and 13 C NMR spectroscopy as well as gel permeation chromatography, are stable under the synthesis gas conditions and formed gels in the presence of air.