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During the past two decades a variety of transition-metal catalyzed reactions have been introducedin synthetic organic chemistry. Among the most popular examples are asymmetric oxidations and reductionsand a variety of cross-coupling reactions to form C − C and C-heteroatom bonds. Examples are the Heck reaction, Suzuki–Kumadaand Sonagashira coupling reactions and the aryl-aminations introduced by...
The use of temperature-dependent multi-component solvent-systems (TMS) as a new recycling conceptwas investigated. The temperature dependency of the solvent systems and suitable compositions for variousreactions were determined by cloud titrations. The results were summarized in an expert system for thesolvent selection. Appropriate thermomorphic solvent systems were applied to different C − Cbond-forming...
In this chapter recent developments in catalyst recycling employing thermomorphic ligands based onpolyethylene glycol will be reviewed. The main focus will lie on the hydroformylation of higher olefins.The general principles of thermoregulated phase-transfer catalysis and thermoregulated phase-separable catalysiswill be explained and the use of this recycling technique in hydroformylation catalysis...
The absolute solubilities of fluorous compounds can be tailored by varying the lengths of the (CF2)n−1CF3 (Rfn)segments. Many such compounds exhibit immense solubility increases in organic solvents or neat liquid reactantsupon heating. Suitably designed fluorous catalysts can therefore be employed under homogeneous conditionsat elevated temperatures, and recovered by solid/liquid...
Promising strategies to use supercritical CO2 (scCO2)for catalyst immobilisation can be developed on the basis of its unique and tunable solubility propertiesin the vicinity of, and especially just beyond, the critical data of pure carbon dioxide. The present chapterdescribes briefly the background and experimental details of four different methods. In the first case,scCO2 is used as a “switch” to...
The present contribution highlights the relationship between scCO2properties, its solubilization power, and its use as a reaction medium for homogeneous catalysis.Current research activities under the lighthouse project “Smart Solvents, Smart Ligands”are presented, the focus being on criteria of conducting catalyzed processes in future applications.
The principle of catalytic SILP materials involves surface modification of a porous solid materialby an ionic liquid coating. Ionic liquids are salts with melting points below 100°C, generally characterizedby extremely low volatilities. In the examples described in this paper, the ionic liquid coating containsa homogeneously dissolved Rh-complex and constitutes a uniform, thin film, which itself displaysthe...
Reaction engineering aspects of aqueous multiphase catalysis were investigated in a discontinuouslystirred batch reactor as well as in a continuously driven loop reactor. The regioselective hydrogenationof α,β-unsaturated aldehydes to the corresponding unsaturated alcohols with a water-solubleand highly active Ru(II)-TPPTS complex catalyst was chosen as model reaction system. Theoretical and experimentalanalysis...
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