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Zirconia-modified copper catalysts are being actively discussed to be beneficial in CO2/H2 conversion to methanol. The nature of the promotional effect of ZrO2 is still an intense matter of debate....

High-pressure in situ IR and NMR investigations of the hydromethoxycarbonylation of 1,3-butadiene (1) to methyl 3-pentenoate (2) in methanol in the presence of Co2(CO)8 and pyridine under carbon monoxide has revealed that the reaction starts by the methanol- and/or pyridine-assisted disproportionation of Co2(CO)8, followed by the establishment of equilibria involving the ionic species [Co(Py)6]2+{[Co(CO)4]−}2, [Co(Py)6]2+[MeO]−[Co(CO)4]−, [PyH]+[Co(CO)4]−, and [MeOH2]+[Co(CO)4]−. The addition of HCo(CO)4 (3) to pyridine or methanol results in the formation of [PyH]+[Co(CO)4]− and [MeOH2]+[Co(CO)4]−, respectively, and 3 is not detectable by either IR or NMR. The ionic 1,4-addition of [MeOH2]+[Co(CO)4]− to 1 is the only pathway to 2-butenylcobalt tetracarbonyl, CH3CH═CHCH2Co(CO)4 (4), via the protonation of 1 followed by the reaction of the C4 carbocation with the counteranion tetracarbonylcobaltate. In the absence of carbon monoxide, 4 could lose a coordinated carbon monoxide to form (η3-C4H7)Co(CO)3 (7) i...

The title compound (1) was prepared by the reaction of 3,5-bis(CF3)C6H3P(i-C3H7)2 (L1) and Co2(CO)8. Its solubility in supercritical carbon dioxide was measured at varying temperatures and pressures using a modified analytical extraction device. Solubility data were determined in the temperature and pressure ranges between 40 and 70 °C and between 100 and 300 bar, respectively. The solubility of 1 is lower compared to (p-CF3C6H4)3P, but much higher than for transition metal complexes bearing phosphines without fluorinated substituents.

The homogeneously catalyzed hydroformylation of linear olefins was investigated at pressures ranging from 7 to 550 MPa. A change in the selectivity was observed, which was reflected by a change of the product distribution. At high-pressures, increased yields of aldehydes were also obtained from the hydroformylation of sterically hindered olefins.

The ruthenium-catalysed hydrosilylation of CO2 was studied with respect to the influences of the solvent present and different co-ligands used. Nitriles exhibit favourable properties as a solvent for this reaction. The catalytic activity of [RuCl(MeCN)5]+[(trans)-RuCl4(MeCN)2]− as pre-catalyst may be increased by additional phosphine ligand. Further N-donor substituents in the phosphine do not result in an increased activity. The homogeneous catalyst may be recycled effectively by a thermal separation of the reaction product. For this procedure, the catalytic activity kept constant during 10 runs.

Recent results on the heterogeneously catalyzed co-oligomerization of 1,3-butadiene and carbon dioxide are presented. Optimized preparation methods for the reaction of Pd(η3-C3H5)(η5-C5H5) 2 with [(i-Pr)2P–CH2]-polystyrene derivative PS-P yield palladium catalysts immobilized on polystyrene support (PS-01, PS-02, PS-03). Consequently, `leaching' is reduced and catalysts may be re-used several times after a simple separation and cleaning procedure. Additionally, a similar immobilization of palladium complex units on silica is reported. The correlation of the formation of 2-[(E)-ethylidene]-6-heptene-5-olide 1 with process parameters such as temperature, kind of catalyst, and solvent, is presented and discussed in detail. Analytical methods (CP-MAS-NMR, XPS, SEM) were used to determine PS-02 before and after use. XPS data indicate an initial Pd0 oxidation state. Used PS-02 possesses a changed coordination sphere around the anchored palladium centres which agrees to its different catalytic behaviour.

‘In situ’ catalysts prepared from (η5-C5H5)Pd(η3-C3H5) 9 and phosphinoalkyl nitriles 10a–e of the general formula (iC3H7)2P(CH2)nCN have been used to catalyse the co-oligomerisation of 1,3-butadiene and carbon dioxide. The δ-lactone 2-ethylidene-6-heptene-5-olid 1 is formed, yielding up to 74%. Different solvent systems have been used of which pyridine provides the best result. The catalysis may also be performed without additional solvent. A minimum of five CH2 units (n = 5) within the ligand is necessary to produce 1 with a selectivity higher than 29% in a solvent-free reaction. Therefore, phosphinoalkyl nitriles of the type described here are acting as hemilabile ligands in the catalytic cycle.

Immobilized catalysts prepared from [Pd(η 5 -C 5 H 5 )(η 3 -C 3 H 5 )] ( 5 ) and polymer bound phosphines 4a–c are used to catalyse C,C coupling reactions of carbon dioxide and any organic co-substrate for the first time in a heterogeneous way. These phosphines, synthesised from chloromethylated polystyrene, are characterised by their elemental analysis data and NMR spectra. The immobilized catalyst from polymer 4a and 5 catalyses the formation of the δ-lactone 2-ethylidene-6-heptene-5-olid ( 1 ). With low reaction rates, up to 72% selectivity to 1 is observed, These catalysts can be used in multiple reactions. In an analogous procedure using polymer 4b , the synthesis of C 17 carboxylic esters is successful.