Polymer 1-octene, hydroformylation

In a first test reaction, the polymer support was used for the hydroformylation of 1-octene in water in the presence of Rh(CO)2acac. Within a reaction time of 10 h at 120°C and a H2/CO (1 1) pressure of 5 MPa, conversion of up to 94% was obtained. The n iso ratio was 3 1, sometimes reaching 9 1. The quantities of 3-and 4-nonanal resulting from olefin isomerization, were below 5% [74]. The versa-tihty of the polymer support was further demonstrated with the Heck reaction of styrene and iodobenzene in the presence of Pd(OAc)2 as the metal catalyst The reaction was again performed in pure water at 50 °C and product yield of up to 80% was obtained after 20 h reaction time [75]. 

Hydroform ylation catalysts based on soluble organic polymers have also been described in the patent literature (55). For example, Trevillyan has reported using a polyphenylene-bound diphenylphosphine ligand to form a tertiary phosphine cobalt carbonyl complex useful in hydroformylation of 1-octene to mainly nonanal and 2-methyloctanal. 

In contrast, SDPP homopolymerization proceeded in a fast and uncontrolled manner. The polymer was tested in the rhodium-catalyzed hydroformylation of 1-octene where a higher //i-ratio but a lower activity was found in comparison to the reaction with the monomeric ligand PPh3. 

The hydrophilic polymer-based rhodium complex depicted below was examined in four consecutive runs in the hydroformylation of 1-octene using an aqueous two-phase system (50 bar syngas, 100 C, 2 h) [56]. The n-regioselectivity was influenced by the polymeric backbone, leading to an lib ratio of 72 28 after the first run. After the fourth run, the catalytic system reached a TOF of 2360 h which is comparable to that found with a corresponding monomeric rhodium complex (2400 h , lib = 40 60). 

High-pressure in situ ETIR and polymer matrix techniques were used to study the rhodium-catalyzed hydroformylation of 1-octene, 1-butene, propene, and ethene using Rh(acac)(CO)2 or Rh(acac)(CO)(PPh3) in a polyethylene matrix as the catalyst precursor. The acyl rhodium intermediates, RC(=0)Rh(C0)4 and RC(=0)Rh (CO)3(PPh3), were observed. It was found that the acyl rhodium tetracarbonyl intermediates easily react with ethene to form acyl rhodium tricarbonyl species RC(=0)Rh(C0)3(C2H4) [61]. Deuterioformylation of l-phenyl-l-(n-pyridyl)-ethenes in the presence of a phosphane-modified Rh4(CO)i2 as catalyst precursor was carried out at 100 bar of CO D2 = 1 1 and 80 °C at partial substrate conversion. On basis ofa direct NMR analysis of the crude reaction mixture, it was concluded that the branched alkyl rhodium intermediate is almost exclusively formed [62]. 

Nixantphos (3S) and its modified derivatives were immobilized on soluble and solid polymer supports, such as dendrimers, polyglycerol, and polyurethanes. The new catalysts were tested in rhodium-catalyzed regioselective hydroformylation of 1-octene and proved to be selective and reusable. Polymer support was found to require spacers between the ligand and the supporting units [92]. 

N-heterocyclic carbene (NHC) palladium complexes supported by three amphiphilic water-soluble block copolymers were synthesized by Nuyken and coworkers [66]. The polymer-bound complexes formed emulsions in water. The resulting macroligand was applied in tlie hydroformylation of 1-octene under aqueous two-phase conditions in four consecutive cycles and showed high activity... 

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